4824 lines
130 KiB
C
4824 lines
130 KiB
C
/*
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* Generic process-grouping system.
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*
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* Based originally on the cpuset system, extracted by Paul Menage
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* Copyright (C) 2006 Google, Inc
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*
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* Notifications support
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* Copyright (C) 2009 Nokia Corporation
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* Author: Kirill A. Shutemov
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*
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* Copyright notices from the original cpuset code:
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* --------------------------------------------------
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* Copyright (C) 2003 BULL SA.
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* Copyright (C) 2004-2006 Silicon Graphics, Inc.
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*
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* Portions derived from Patrick Mochel's sysfs code.
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* sysfs is Copyright (c) 2001-3 Patrick Mochel
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*
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* 2003-10-10 Written by Simon Derr.
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* 2003-10-22 Updates by Stephen Hemminger.
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* 2004 May-July Rework by Paul Jackson.
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* ---------------------------------------------------
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*
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* This file is subject to the terms and conditions of the GNU General Public
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* License. See the file COPYING in the main directory of the Linux
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* distribution for more details.
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*/
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#include <linux/cgroup.h>
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#include <linux/cred.h>
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#include <linux/ctype.h>
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#include <linux/errno.h>
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#include <linux/init_task.h>
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#include <linux/kernel.h>
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#include <linux/list.h>
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#include <linux/mm.h>
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#include <linux/mutex.h>
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#include <linux/mount.h>
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#include <linux/pagemap.h>
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#include <linux/proc_fs.h>
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#include <linux/rcupdate.h>
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#include <linux/sched.h>
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#include <linux/slab.h>
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#include <linux/spinlock.h>
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#include <linux/rwsem.h>
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#include <linux/string.h>
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#include <linux/sort.h>
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#include <linux/kmod.h>
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#include <linux/delayacct.h>
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#include <linux/cgroupstats.h>
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#include <linux/hashtable.h>
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#include <linux/pid_namespace.h>
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#include <linux/idr.h>
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#include <linux/vmalloc.h> /* TODO: replace with more sophisticated array */
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#include <linux/kthread.h>
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#include <linux/delay.h>
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#include <linux/atomic.h>
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/*
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* pidlists linger the following amount before being destroyed. The goal
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* is avoiding frequent destruction in the middle of consecutive read calls
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* Expiring in the middle is a performance problem not a correctness one.
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* 1 sec should be enough.
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*/
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#define CGROUP_PIDLIST_DESTROY_DELAY HZ
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#define CGROUP_FILE_NAME_MAX (MAX_CGROUP_TYPE_NAMELEN + \
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MAX_CFTYPE_NAME + 2)
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/*
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* cgroup_tree_mutex nests above cgroup_mutex and protects cftypes, file
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* creation/removal and hierarchy changing operations including cgroup
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* creation, removal, css association and controller rebinding. This outer
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* lock is needed mainly to resolve the circular dependency between kernfs
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* active ref and cgroup_mutex. cgroup_tree_mutex nests above both.
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*/
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static DEFINE_MUTEX(cgroup_tree_mutex);
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/*
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* cgroup_mutex is the master lock. Any modification to cgroup or its
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* hierarchy must be performed while holding it.
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*
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* css_set_rwsem protects task->cgroups pointer, the list of css_set
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* objects, and the chain of tasks off each css_set.
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*
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* These locks are exported if CONFIG_PROVE_RCU so that accessors in
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* cgroup.h can use them for lockdep annotations.
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*/
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#ifdef CONFIG_PROVE_RCU
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DEFINE_MUTEX(cgroup_mutex);
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DECLARE_RWSEM(css_set_rwsem);
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EXPORT_SYMBOL_GPL(cgroup_mutex);
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EXPORT_SYMBOL_GPL(css_set_rwsem);
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#else
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static DEFINE_MUTEX(cgroup_mutex);
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static DECLARE_RWSEM(css_set_rwsem);
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#endif
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/*
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* Protects cgroup_subsys->release_agent_path. Modifying it also requires
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* cgroup_mutex. Reading requires either cgroup_mutex or this spinlock.
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*/
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static DEFINE_SPINLOCK(release_agent_path_lock);
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#define cgroup_assert_mutexes_or_rcu_locked() \
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rcu_lockdep_assert(rcu_read_lock_held() || \
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lockdep_is_held(&cgroup_tree_mutex) || \
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lockdep_is_held(&cgroup_mutex), \
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"cgroup_[tree_]mutex or RCU read lock required");
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/*
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* cgroup destruction makes heavy use of work items and there can be a lot
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* of concurrent destructions. Use a separate workqueue so that cgroup
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* destruction work items don't end up filling up max_active of system_wq
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* which may lead to deadlock.
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*/
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static struct workqueue_struct *cgroup_destroy_wq;
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/*
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* pidlist destructions need to be flushed on cgroup destruction. Use a
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* separate workqueue as flush domain.
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*/
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static struct workqueue_struct *cgroup_pidlist_destroy_wq;
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/* generate an array of cgroup subsystem pointers */
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#define SUBSYS(_x) [_x ## _cgrp_id] = &_x ## _cgrp_subsys,
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static struct cgroup_subsys *cgroup_subsys[] = {
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#include <linux/cgroup_subsys.h>
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};
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#undef SUBSYS
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/* array of cgroup subsystem names */
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#define SUBSYS(_x) [_x ## _cgrp_id] = #_x,
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static const char *cgroup_subsys_name[] = {
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#include <linux/cgroup_subsys.h>
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};
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#undef SUBSYS
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/*
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* The default hierarchy, reserved for the subsystems that are otherwise
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* unattached - it never has more than a single cgroup, and all tasks are
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* part of that cgroup.
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*/
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struct cgroup_root cgrp_dfl_root;
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/*
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* The default hierarchy always exists but is hidden until mounted for the
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* first time. This is for backward compatibility.
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*/
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static bool cgrp_dfl_root_visible;
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/* The list of hierarchy roots */
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static LIST_HEAD(cgroup_roots);
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static int cgroup_root_count;
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/* hierarchy ID allocation and mapping, protected by cgroup_mutex */
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static DEFINE_IDR(cgroup_hierarchy_idr);
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/*
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* Assign a monotonically increasing serial number to cgroups. It
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* guarantees cgroups with bigger numbers are newer than those with smaller
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* numbers. Also, as cgroups are always appended to the parent's
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* ->children list, it guarantees that sibling cgroups are always sorted in
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* the ascending serial number order on the list. Protected by
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* cgroup_mutex.
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*/
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static u64 cgroup_serial_nr_next = 1;
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/* This flag indicates whether tasks in the fork and exit paths should
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* check for fork/exit handlers to call. This avoids us having to do
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* extra work in the fork/exit path if none of the subsystems need to
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* be called.
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*/
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static int need_forkexit_callback __read_mostly;
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static struct cftype cgroup_base_files[];
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static void cgroup_put(struct cgroup *cgrp);
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static int rebind_subsystems(struct cgroup_root *dst_root,
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unsigned long ss_mask);
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static void cgroup_destroy_css_killed(struct cgroup *cgrp);
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static int cgroup_destroy_locked(struct cgroup *cgrp);
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static int cgroup_addrm_files(struct cgroup *cgrp, struct cftype cfts[],
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bool is_add);
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static void cgroup_pidlist_destroy_all(struct cgroup *cgrp);
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/**
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* cgroup_css - obtain a cgroup's css for the specified subsystem
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* @cgrp: the cgroup of interest
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* @ss: the subsystem of interest (%NULL returns the dummy_css)
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*
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* Return @cgrp's css (cgroup_subsys_state) associated with @ss. This
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* function must be called either under cgroup_mutex or rcu_read_lock() and
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* the caller is responsible for pinning the returned css if it wants to
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* keep accessing it outside the said locks. This function may return
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* %NULL if @cgrp doesn't have @subsys_id enabled.
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*/
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static struct cgroup_subsys_state *cgroup_css(struct cgroup *cgrp,
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struct cgroup_subsys *ss)
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{
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if (ss)
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return rcu_dereference_check(cgrp->subsys[ss->id],
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lockdep_is_held(&cgroup_tree_mutex) ||
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lockdep_is_held(&cgroup_mutex));
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else
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return &cgrp->dummy_css;
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}
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/* convenient tests for these bits */
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static inline bool cgroup_is_dead(const struct cgroup *cgrp)
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{
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return test_bit(CGRP_DEAD, &cgrp->flags);
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}
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struct cgroup_subsys_state *seq_css(struct seq_file *seq)
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{
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struct kernfs_open_file *of = seq->private;
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struct cgroup *cgrp = of->kn->parent->priv;
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struct cftype *cft = seq_cft(seq);
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/*
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* This is open and unprotected implementation of cgroup_css().
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* seq_css() is only called from a kernfs file operation which has
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* an active reference on the file. Because all the subsystem
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* files are drained before a css is disassociated with a cgroup,
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* the matching css from the cgroup's subsys table is guaranteed to
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* be and stay valid until the enclosing operation is complete.
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*/
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if (cft->ss)
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return rcu_dereference_raw(cgrp->subsys[cft->ss->id]);
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else
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return &cgrp->dummy_css;
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}
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EXPORT_SYMBOL_GPL(seq_css);
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/**
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* cgroup_is_descendant - test ancestry
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* @cgrp: the cgroup to be tested
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* @ancestor: possible ancestor of @cgrp
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*
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* Test whether @cgrp is a descendant of @ancestor. It also returns %true
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* if @cgrp == @ancestor. This function is safe to call as long as @cgrp
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* and @ancestor are accessible.
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*/
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bool cgroup_is_descendant(struct cgroup *cgrp, struct cgroup *ancestor)
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{
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while (cgrp) {
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if (cgrp == ancestor)
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return true;
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cgrp = cgrp->parent;
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}
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return false;
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}
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static int cgroup_is_releasable(const struct cgroup *cgrp)
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{
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const int bits =
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(1 << CGRP_RELEASABLE) |
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(1 << CGRP_NOTIFY_ON_RELEASE);
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return (cgrp->flags & bits) == bits;
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}
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static int notify_on_release(const struct cgroup *cgrp)
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{
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return test_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags);
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}
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/**
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* for_each_css - iterate all css's of a cgroup
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* @css: the iteration cursor
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* @ssid: the index of the subsystem, CGROUP_SUBSYS_COUNT after reaching the end
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* @cgrp: the target cgroup to iterate css's of
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*
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* Should be called under cgroup_mutex.
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*/
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#define for_each_css(css, ssid, cgrp) \
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for ((ssid) = 0; (ssid) < CGROUP_SUBSYS_COUNT; (ssid)++) \
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if (!((css) = rcu_dereference_check( \
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(cgrp)->subsys[(ssid)], \
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lockdep_is_held(&cgroup_tree_mutex) || \
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lockdep_is_held(&cgroup_mutex)))) { } \
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else
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/**
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* for_each_subsys - iterate all enabled cgroup subsystems
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* @ss: the iteration cursor
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* @ssid: the index of @ss, CGROUP_SUBSYS_COUNT after reaching the end
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*/
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#define for_each_subsys(ss, ssid) \
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for ((ssid) = 0; (ssid) < CGROUP_SUBSYS_COUNT && \
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(((ss) = cgroup_subsys[ssid]) || true); (ssid)++)
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/* iterate across the hierarchies */
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#define for_each_root(root) \
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list_for_each_entry((root), &cgroup_roots, root_list)
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/**
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* cgroup_lock_live_group - take cgroup_mutex and check that cgrp is alive.
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* @cgrp: the cgroup to be checked for liveness
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*
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* On success, returns true; the mutex should be later unlocked. On
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* failure returns false with no lock held.
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*/
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static bool cgroup_lock_live_group(struct cgroup *cgrp)
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{
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mutex_lock(&cgroup_mutex);
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if (cgroup_is_dead(cgrp)) {
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mutex_unlock(&cgroup_mutex);
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return false;
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}
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return true;
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}
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/* the list of cgroups eligible for automatic release. Protected by
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* release_list_lock */
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static LIST_HEAD(release_list);
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static DEFINE_RAW_SPINLOCK(release_list_lock);
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static void cgroup_release_agent(struct work_struct *work);
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static DECLARE_WORK(release_agent_work, cgroup_release_agent);
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static void check_for_release(struct cgroup *cgrp);
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/*
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* A cgroup can be associated with multiple css_sets as different tasks may
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* belong to different cgroups on different hierarchies. In the other
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* direction, a css_set is naturally associated with multiple cgroups.
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* This M:N relationship is represented by the following link structure
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* which exists for each association and allows traversing the associations
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* from both sides.
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*/
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struct cgrp_cset_link {
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/* the cgroup and css_set this link associates */
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struct cgroup *cgrp;
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struct css_set *cset;
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/* list of cgrp_cset_links anchored at cgrp->cset_links */
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struct list_head cset_link;
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/* list of cgrp_cset_links anchored at css_set->cgrp_links */
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struct list_head cgrp_link;
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};
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/*
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* The default css_set - used by init and its children prior to any
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* hierarchies being mounted. It contains a pointer to the root state
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* for each subsystem. Also used to anchor the list of css_sets. Not
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* reference-counted, to improve performance when child cgroups
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* haven't been created.
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*/
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static struct css_set init_css_set = {
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.refcount = ATOMIC_INIT(1),
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.cgrp_links = LIST_HEAD_INIT(init_css_set.cgrp_links),
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.tasks = LIST_HEAD_INIT(init_css_set.tasks),
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.mg_tasks = LIST_HEAD_INIT(init_css_set.mg_tasks),
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.mg_preload_node = LIST_HEAD_INIT(init_css_set.mg_preload_node),
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.mg_node = LIST_HEAD_INIT(init_css_set.mg_node),
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};
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static int css_set_count = 1; /* 1 for init_css_set */
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/*
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* hash table for cgroup groups. This improves the performance to find
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* an existing css_set. This hash doesn't (currently) take into
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* account cgroups in empty hierarchies.
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*/
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#define CSS_SET_HASH_BITS 7
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static DEFINE_HASHTABLE(css_set_table, CSS_SET_HASH_BITS);
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static unsigned long css_set_hash(struct cgroup_subsys_state *css[])
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{
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unsigned long key = 0UL;
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struct cgroup_subsys *ss;
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int i;
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for_each_subsys(ss, i)
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key += (unsigned long)css[i];
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key = (key >> 16) ^ key;
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return key;
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}
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static void put_css_set_locked(struct css_set *cset, bool taskexit)
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{
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struct cgrp_cset_link *link, *tmp_link;
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lockdep_assert_held(&css_set_rwsem);
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if (!atomic_dec_and_test(&cset->refcount))
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return;
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/* This css_set is dead. unlink it and release cgroup refcounts */
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hash_del(&cset->hlist);
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css_set_count--;
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list_for_each_entry_safe(link, tmp_link, &cset->cgrp_links, cgrp_link) {
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struct cgroup *cgrp = link->cgrp;
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list_del(&link->cset_link);
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list_del(&link->cgrp_link);
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/* @cgrp can't go away while we're holding css_set_rwsem */
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if (list_empty(&cgrp->cset_links) && notify_on_release(cgrp)) {
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if (taskexit)
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set_bit(CGRP_RELEASABLE, &cgrp->flags);
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check_for_release(cgrp);
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}
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kfree(link);
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}
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kfree_rcu(cset, rcu_head);
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}
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static void put_css_set(struct css_set *cset, bool taskexit)
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{
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/*
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* Ensure that the refcount doesn't hit zero while any readers
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* can see it. Similar to atomic_dec_and_lock(), but for an
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* rwlock
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*/
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if (atomic_add_unless(&cset->refcount, -1, 1))
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return;
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|
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down_write(&css_set_rwsem);
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put_css_set_locked(cset, taskexit);
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up_write(&css_set_rwsem);
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}
|
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|
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/*
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* refcounted get/put for css_set objects
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*/
|
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static inline void get_css_set(struct css_set *cset)
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{
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atomic_inc(&cset->refcount);
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}
|
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|
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/**
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* compare_css_sets - helper function for find_existing_css_set().
|
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* @cset: candidate css_set being tested
|
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* @old_cset: existing css_set for a task
|
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* @new_cgrp: cgroup that's being entered by the task
|
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* @template: desired set of css pointers in css_set (pre-calculated)
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*
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* Returns true if "cset" matches "old_cset" except for the hierarchy
|
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* which "new_cgrp" belongs to, for which it should match "new_cgrp".
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*/
|
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static bool compare_css_sets(struct css_set *cset,
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struct css_set *old_cset,
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struct cgroup *new_cgrp,
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struct cgroup_subsys_state *template[])
|
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{
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struct list_head *l1, *l2;
|
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|
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if (memcmp(template, cset->subsys, sizeof(cset->subsys))) {
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/* Not all subsystems matched */
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return false;
|
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}
|
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|
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/*
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* Compare cgroup pointers in order to distinguish between
|
|
* different cgroups in heirarchies with no subsystems. We
|
|
* could get by with just this check alone (and skip the
|
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* memcmp above) but on most setups the memcmp check will
|
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* avoid the need for this more expensive check on almost all
|
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* candidates.
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*/
|
|
|
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l1 = &cset->cgrp_links;
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l2 = &old_cset->cgrp_links;
|
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while (1) {
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struct cgrp_cset_link *link1, *link2;
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struct cgroup *cgrp1, *cgrp2;
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|
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l1 = l1->next;
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l2 = l2->next;
|
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/* See if we reached the end - both lists are equal length. */
|
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if (l1 == &cset->cgrp_links) {
|
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BUG_ON(l2 != &old_cset->cgrp_links);
|
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break;
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} else {
|
|
BUG_ON(l2 == &old_cset->cgrp_links);
|
|
}
|
|
/* Locate the cgroups associated with these links. */
|
|
link1 = list_entry(l1, struct cgrp_cset_link, cgrp_link);
|
|
link2 = list_entry(l2, struct cgrp_cset_link, cgrp_link);
|
|
cgrp1 = link1->cgrp;
|
|
cgrp2 = link2->cgrp;
|
|
/* Hierarchies should be linked in the same order. */
|
|
BUG_ON(cgrp1->root != cgrp2->root);
|
|
|
|
/*
|
|
* If this hierarchy is the hierarchy of the cgroup
|
|
* that's changing, then we need to check that this
|
|
* css_set points to the new cgroup; if it's any other
|
|
* hierarchy, then this css_set should point to the
|
|
* same cgroup as the old css_set.
|
|
*/
|
|
if (cgrp1->root == new_cgrp->root) {
|
|
if (cgrp1 != new_cgrp)
|
|
return false;
|
|
} else {
|
|
if (cgrp1 != cgrp2)
|
|
return false;
|
|
}
|
|
}
|
|
return true;
|
|
}
|
|
|
|
/**
|
|
* find_existing_css_set - init css array and find the matching css_set
|
|
* @old_cset: the css_set that we're using before the cgroup transition
|
|
* @cgrp: the cgroup that we're moving into
|
|
* @template: out param for the new set of csses, should be clear on entry
|
|
*/
|
|
static struct css_set *find_existing_css_set(struct css_set *old_cset,
|
|
struct cgroup *cgrp,
|
|
struct cgroup_subsys_state *template[])
|
|
{
|
|
struct cgroup_root *root = cgrp->root;
|
|
struct cgroup_subsys *ss;
|
|
struct css_set *cset;
|
|
unsigned long key;
|
|
int i;
|
|
|
|
/*
|
|
* Build the set of subsystem state objects that we want to see in the
|
|
* new css_set. while subsystems can change globally, the entries here
|
|
* won't change, so no need for locking.
|
|
*/
|
|
for_each_subsys(ss, i) {
|
|
if (root->cgrp.subsys_mask & (1UL << i)) {
|
|
/* Subsystem is in this hierarchy. So we want
|
|
* the subsystem state from the new
|
|
* cgroup */
|
|
template[i] = cgroup_css(cgrp, ss);
|
|
} else {
|
|
/* Subsystem is not in this hierarchy, so we
|
|
* don't want to change the subsystem state */
|
|
template[i] = old_cset->subsys[i];
|
|
}
|
|
}
|
|
|
|
key = css_set_hash(template);
|
|
hash_for_each_possible(css_set_table, cset, hlist, key) {
|
|
if (!compare_css_sets(cset, old_cset, cgrp, template))
|
|
continue;
|
|
|
|
/* This css_set matches what we need */
|
|
return cset;
|
|
}
|
|
|
|
/* No existing cgroup group matched */
|
|
return NULL;
|
|
}
|
|
|
|
static void free_cgrp_cset_links(struct list_head *links_to_free)
|
|
{
|
|
struct cgrp_cset_link *link, *tmp_link;
|
|
|
|
list_for_each_entry_safe(link, tmp_link, links_to_free, cset_link) {
|
|
list_del(&link->cset_link);
|
|
kfree(link);
|
|
}
|
|
}
|
|
|
|
/**
|
|
* allocate_cgrp_cset_links - allocate cgrp_cset_links
|
|
* @count: the number of links to allocate
|
|
* @tmp_links: list_head the allocated links are put on
|
|
*
|
|
* Allocate @count cgrp_cset_link structures and chain them on @tmp_links
|
|
* through ->cset_link. Returns 0 on success or -errno.
|
|
*/
|
|
static int allocate_cgrp_cset_links(int count, struct list_head *tmp_links)
|
|
{
|
|
struct cgrp_cset_link *link;
|
|
int i;
|
|
|
|
INIT_LIST_HEAD(tmp_links);
|
|
|
|
for (i = 0; i < count; i++) {
|
|
link = kzalloc(sizeof(*link), GFP_KERNEL);
|
|
if (!link) {
|
|
free_cgrp_cset_links(tmp_links);
|
|
return -ENOMEM;
|
|
}
|
|
list_add(&link->cset_link, tmp_links);
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
/**
|
|
* link_css_set - a helper function to link a css_set to a cgroup
|
|
* @tmp_links: cgrp_cset_link objects allocated by allocate_cgrp_cset_links()
|
|
* @cset: the css_set to be linked
|
|
* @cgrp: the destination cgroup
|
|
*/
|
|
static void link_css_set(struct list_head *tmp_links, struct css_set *cset,
|
|
struct cgroup *cgrp)
|
|
{
|
|
struct cgrp_cset_link *link;
|
|
|
|
BUG_ON(list_empty(tmp_links));
|
|
link = list_first_entry(tmp_links, struct cgrp_cset_link, cset_link);
|
|
link->cset = cset;
|
|
link->cgrp = cgrp;
|
|
list_move(&link->cset_link, &cgrp->cset_links);
|
|
/*
|
|
* Always add links to the tail of the list so that the list
|
|
* is sorted by order of hierarchy creation
|
|
*/
|
|
list_add_tail(&link->cgrp_link, &cset->cgrp_links);
|
|
}
|
|
|
|
/**
|
|
* find_css_set - return a new css_set with one cgroup updated
|
|
* @old_cset: the baseline css_set
|
|
* @cgrp: the cgroup to be updated
|
|
*
|
|
* Return a new css_set that's equivalent to @old_cset, but with @cgrp
|
|
* substituted into the appropriate hierarchy.
|
|
*/
|
|
static struct css_set *find_css_set(struct css_set *old_cset,
|
|
struct cgroup *cgrp)
|
|
{
|
|
struct cgroup_subsys_state *template[CGROUP_SUBSYS_COUNT] = { };
|
|
struct css_set *cset;
|
|
struct list_head tmp_links;
|
|
struct cgrp_cset_link *link;
|
|
unsigned long key;
|
|
|
|
lockdep_assert_held(&cgroup_mutex);
|
|
|
|
/* First see if we already have a cgroup group that matches
|
|
* the desired set */
|
|
down_read(&css_set_rwsem);
|
|
cset = find_existing_css_set(old_cset, cgrp, template);
|
|
if (cset)
|
|
get_css_set(cset);
|
|
up_read(&css_set_rwsem);
|
|
|
|
if (cset)
|
|
return cset;
|
|
|
|
cset = kzalloc(sizeof(*cset), GFP_KERNEL);
|
|
if (!cset)
|
|
return NULL;
|
|
|
|
/* Allocate all the cgrp_cset_link objects that we'll need */
|
|
if (allocate_cgrp_cset_links(cgroup_root_count, &tmp_links) < 0) {
|
|
kfree(cset);
|
|
return NULL;
|
|
}
|
|
|
|
atomic_set(&cset->refcount, 1);
|
|
INIT_LIST_HEAD(&cset->cgrp_links);
|
|
INIT_LIST_HEAD(&cset->tasks);
|
|
INIT_LIST_HEAD(&cset->mg_tasks);
|
|
INIT_LIST_HEAD(&cset->mg_preload_node);
|
|
INIT_LIST_HEAD(&cset->mg_node);
|
|
INIT_HLIST_NODE(&cset->hlist);
|
|
|
|
/* Copy the set of subsystem state objects generated in
|
|
* find_existing_css_set() */
|
|
memcpy(cset->subsys, template, sizeof(cset->subsys));
|
|
|
|
down_write(&css_set_rwsem);
|
|
/* Add reference counts and links from the new css_set. */
|
|
list_for_each_entry(link, &old_cset->cgrp_links, cgrp_link) {
|
|
struct cgroup *c = link->cgrp;
|
|
|
|
if (c->root == cgrp->root)
|
|
c = cgrp;
|
|
link_css_set(&tmp_links, cset, c);
|
|
}
|
|
|
|
BUG_ON(!list_empty(&tmp_links));
|
|
|
|
css_set_count++;
|
|
|
|
/* Add this cgroup group to the hash table */
|
|
key = css_set_hash(cset->subsys);
|
|
hash_add(css_set_table, &cset->hlist, key);
|
|
|
|
up_write(&css_set_rwsem);
|
|
|
|
return cset;
|
|
}
|
|
|
|
static struct cgroup_root *cgroup_root_from_kf(struct kernfs_root *kf_root)
|
|
{
|
|
struct cgroup *root_cgrp = kf_root->kn->priv;
|
|
|
|
return root_cgrp->root;
|
|
}
|
|
|
|
static int cgroup_init_root_id(struct cgroup_root *root)
|
|
{
|
|
int id;
|
|
|
|
lockdep_assert_held(&cgroup_mutex);
|
|
|
|
id = idr_alloc_cyclic(&cgroup_hierarchy_idr, root, 0, 0, GFP_KERNEL);
|
|
if (id < 0)
|
|
return id;
|
|
|
|
root->hierarchy_id = id;
|
|
return 0;
|
|
}
|
|
|
|
static void cgroup_exit_root_id(struct cgroup_root *root)
|
|
{
|
|
lockdep_assert_held(&cgroup_mutex);
|
|
|
|
if (root->hierarchy_id) {
|
|
idr_remove(&cgroup_hierarchy_idr, root->hierarchy_id);
|
|
root->hierarchy_id = 0;
|
|
}
|
|
}
|
|
|
|
static void cgroup_free_root(struct cgroup_root *root)
|
|
{
|
|
if (root) {
|
|
/* hierarhcy ID shoulid already have been released */
|
|
WARN_ON_ONCE(root->hierarchy_id);
|
|
|
|
idr_destroy(&root->cgroup_idr);
|
|
kfree(root);
|
|
}
|
|
}
|
|
|
|
static void cgroup_destroy_root(struct cgroup_root *root)
|
|
{
|
|
struct cgroup *cgrp = &root->cgrp;
|
|
struct cgrp_cset_link *link, *tmp_link;
|
|
|
|
mutex_lock(&cgroup_tree_mutex);
|
|
mutex_lock(&cgroup_mutex);
|
|
|
|
BUG_ON(atomic_read(&root->nr_cgrps));
|
|
BUG_ON(!list_empty(&cgrp->children));
|
|
|
|
/* Rebind all subsystems back to the default hierarchy */
|
|
rebind_subsystems(&cgrp_dfl_root, cgrp->subsys_mask);
|
|
|
|
/*
|
|
* Release all the links from cset_links to this hierarchy's
|
|
* root cgroup
|
|
*/
|
|
down_write(&css_set_rwsem);
|
|
|
|
list_for_each_entry_safe(link, tmp_link, &cgrp->cset_links, cset_link) {
|
|
list_del(&link->cset_link);
|
|
list_del(&link->cgrp_link);
|
|
kfree(link);
|
|
}
|
|
up_write(&css_set_rwsem);
|
|
|
|
if (!list_empty(&root->root_list)) {
|
|
list_del(&root->root_list);
|
|
cgroup_root_count--;
|
|
}
|
|
|
|
cgroup_exit_root_id(root);
|
|
|
|
mutex_unlock(&cgroup_mutex);
|
|
mutex_unlock(&cgroup_tree_mutex);
|
|
|
|
kernfs_destroy_root(root->kf_root);
|
|
cgroup_free_root(root);
|
|
}
|
|
|
|
/* look up cgroup associated with given css_set on the specified hierarchy */
|
|
static struct cgroup *cset_cgroup_from_root(struct css_set *cset,
|
|
struct cgroup_root *root)
|
|
{
|
|
struct cgroup *res = NULL;
|
|
|
|
lockdep_assert_held(&cgroup_mutex);
|
|
lockdep_assert_held(&css_set_rwsem);
|
|
|
|
if (cset == &init_css_set) {
|
|
res = &root->cgrp;
|
|
} else {
|
|
struct cgrp_cset_link *link;
|
|
|
|
list_for_each_entry(link, &cset->cgrp_links, cgrp_link) {
|
|
struct cgroup *c = link->cgrp;
|
|
|
|
if (c->root == root) {
|
|
res = c;
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
|
|
BUG_ON(!res);
|
|
return res;
|
|
}
|
|
|
|
/*
|
|
* Return the cgroup for "task" from the given hierarchy. Must be
|
|
* called with cgroup_mutex and css_set_rwsem held.
|
|
*/
|
|
static struct cgroup *task_cgroup_from_root(struct task_struct *task,
|
|
struct cgroup_root *root)
|
|
{
|
|
/*
|
|
* No need to lock the task - since we hold cgroup_mutex the
|
|
* task can't change groups, so the only thing that can happen
|
|
* is that it exits and its css is set back to init_css_set.
|
|
*/
|
|
return cset_cgroup_from_root(task_css_set(task), root);
|
|
}
|
|
|
|
/*
|
|
* A task must hold cgroup_mutex to modify cgroups.
|
|
*
|
|
* Any task can increment and decrement the count field without lock.
|
|
* So in general, code holding cgroup_mutex can't rely on the count
|
|
* field not changing. However, if the count goes to zero, then only
|
|
* cgroup_attach_task() can increment it again. Because a count of zero
|
|
* means that no tasks are currently attached, therefore there is no
|
|
* way a task attached to that cgroup can fork (the other way to
|
|
* increment the count). So code holding cgroup_mutex can safely
|
|
* assume that if the count is zero, it will stay zero. Similarly, if
|
|
* a task holds cgroup_mutex on a cgroup with zero count, it
|
|
* knows that the cgroup won't be removed, as cgroup_rmdir()
|
|
* needs that mutex.
|
|
*
|
|
* The fork and exit callbacks cgroup_fork() and cgroup_exit(), don't
|
|
* (usually) take cgroup_mutex. These are the two most performance
|
|
* critical pieces of code here. The exception occurs on cgroup_exit(),
|
|
* when a task in a notify_on_release cgroup exits. Then cgroup_mutex
|
|
* is taken, and if the cgroup count is zero, a usermode call made
|
|
* to the release agent with the name of the cgroup (path relative to
|
|
* the root of cgroup file system) as the argument.
|
|
*
|
|
* A cgroup can only be deleted if both its 'count' of using tasks
|
|
* is zero, and its list of 'children' cgroups is empty. Since all
|
|
* tasks in the system use _some_ cgroup, and since there is always at
|
|
* least one task in the system (init, pid == 1), therefore, root cgroup
|
|
* always has either children cgroups and/or using tasks. So we don't
|
|
* need a special hack to ensure that root cgroup cannot be deleted.
|
|
*
|
|
* P.S. One more locking exception. RCU is used to guard the
|
|
* update of a tasks cgroup pointer by cgroup_attach_task()
|
|
*/
|
|
|
|
static int cgroup_populate_dir(struct cgroup *cgrp, unsigned long subsys_mask);
|
|
static struct kernfs_syscall_ops cgroup_kf_syscall_ops;
|
|
static const struct file_operations proc_cgroupstats_operations;
|
|
|
|
static char *cgroup_file_name(struct cgroup *cgrp, const struct cftype *cft,
|
|
char *buf)
|
|
{
|
|
if (cft->ss && !(cft->flags & CFTYPE_NO_PREFIX) &&
|
|
!(cgrp->root->flags & CGRP_ROOT_NOPREFIX))
|
|
snprintf(buf, CGROUP_FILE_NAME_MAX, "%s.%s",
|
|
cft->ss->name, cft->name);
|
|
else
|
|
strncpy(buf, cft->name, CGROUP_FILE_NAME_MAX);
|
|
return buf;
|
|
}
|
|
|
|
/**
|
|
* cgroup_file_mode - deduce file mode of a control file
|
|
* @cft: the control file in question
|
|
*
|
|
* returns cft->mode if ->mode is not 0
|
|
* returns S_IRUGO|S_IWUSR if it has both a read and a write handler
|
|
* returns S_IRUGO if it has only a read handler
|
|
* returns S_IWUSR if it has only a write hander
|
|
*/
|
|
static umode_t cgroup_file_mode(const struct cftype *cft)
|
|
{
|
|
umode_t mode = 0;
|
|
|
|
if (cft->mode)
|
|
return cft->mode;
|
|
|
|
if (cft->read_u64 || cft->read_s64 || cft->seq_show)
|
|
mode |= S_IRUGO;
|
|
|
|
if (cft->write_u64 || cft->write_s64 || cft->write_string ||
|
|
cft->trigger)
|
|
mode |= S_IWUSR;
|
|
|
|
return mode;
|
|
}
|
|
|
|
static void cgroup_free_fn(struct work_struct *work)
|
|
{
|
|
struct cgroup *cgrp = container_of(work, struct cgroup, destroy_work);
|
|
|
|
atomic_dec(&cgrp->root->nr_cgrps);
|
|
cgroup_pidlist_destroy_all(cgrp);
|
|
|
|
if (cgrp->parent) {
|
|
/*
|
|
* We get a ref to the parent, and put the ref when this
|
|
* cgroup is being freed, so it's guaranteed that the
|
|
* parent won't be destroyed before its children.
|
|
*/
|
|
cgroup_put(cgrp->parent);
|
|
kernfs_put(cgrp->kn);
|
|
kfree(cgrp);
|
|
} else {
|
|
/*
|
|
* This is root cgroup's refcnt reaching zero, which
|
|
* indicates that the root should be released.
|
|
*/
|
|
cgroup_destroy_root(cgrp->root);
|
|
}
|
|
}
|
|
|
|
static void cgroup_free_rcu(struct rcu_head *head)
|
|
{
|
|
struct cgroup *cgrp = container_of(head, struct cgroup, rcu_head);
|
|
|
|
INIT_WORK(&cgrp->destroy_work, cgroup_free_fn);
|
|
queue_work(cgroup_destroy_wq, &cgrp->destroy_work);
|
|
}
|
|
|
|
static void cgroup_get(struct cgroup *cgrp)
|
|
{
|
|
WARN_ON_ONCE(cgroup_is_dead(cgrp));
|
|
WARN_ON_ONCE(atomic_read(&cgrp->refcnt) <= 0);
|
|
atomic_inc(&cgrp->refcnt);
|
|
}
|
|
|
|
static void cgroup_put(struct cgroup *cgrp)
|
|
{
|
|
if (!atomic_dec_and_test(&cgrp->refcnt))
|
|
return;
|
|
if (WARN_ON_ONCE(cgrp->parent && !cgroup_is_dead(cgrp)))
|
|
return;
|
|
|
|
/*
|
|
* XXX: cgrp->id is only used to look up css's. As cgroup and
|
|
* css's lifetimes will be decoupled, it should be made
|
|
* per-subsystem and moved to css->id so that lookups are
|
|
* successful until the target css is released.
|
|
*/
|
|
mutex_lock(&cgroup_mutex);
|
|
idr_remove(&cgrp->root->cgroup_idr, cgrp->id);
|
|
mutex_unlock(&cgroup_mutex);
|
|
cgrp->id = -1;
|
|
|
|
call_rcu(&cgrp->rcu_head, cgroup_free_rcu);
|
|
}
|
|
|
|
static void cgroup_rm_file(struct cgroup *cgrp, const struct cftype *cft)
|
|
{
|
|
char name[CGROUP_FILE_NAME_MAX];
|
|
|
|
lockdep_assert_held(&cgroup_tree_mutex);
|
|
kernfs_remove_by_name(cgrp->kn, cgroup_file_name(cgrp, cft, name));
|
|
}
|
|
|
|
/**
|
|
* cgroup_clear_dir - remove subsys files in a cgroup directory
|
|
* @cgrp: target cgroup
|
|
* @subsys_mask: mask of the subsystem ids whose files should be removed
|
|
*/
|
|
static void cgroup_clear_dir(struct cgroup *cgrp, unsigned long subsys_mask)
|
|
{
|
|
struct cgroup_subsys *ss;
|
|
int i;
|
|
|
|
for_each_subsys(ss, i) {
|
|
struct cftype *cfts;
|
|
|
|
if (!test_bit(i, &subsys_mask))
|
|
continue;
|
|
list_for_each_entry(cfts, &ss->cfts, node)
|
|
cgroup_addrm_files(cgrp, cfts, false);
|
|
}
|
|
}
|
|
|
|
static int rebind_subsystems(struct cgroup_root *dst_root,
|
|
unsigned long ss_mask)
|
|
{
|
|
struct cgroup_subsys *ss;
|
|
int ssid, ret;
|
|
|
|
lockdep_assert_held(&cgroup_tree_mutex);
|
|
lockdep_assert_held(&cgroup_mutex);
|
|
|
|
for_each_subsys(ss, ssid) {
|
|
if (!(ss_mask & (1 << ssid)))
|
|
continue;
|
|
|
|
/* if @ss is on the dummy_root, we can always move it */
|
|
if (ss->root == &cgrp_dfl_root)
|
|
continue;
|
|
|
|
/* if @ss has non-root cgroups attached to it, can't move */
|
|
if (!list_empty(&ss->root->cgrp.children))
|
|
return -EBUSY;
|
|
|
|
/* can't move between two non-dummy roots either */
|
|
if (dst_root != &cgrp_dfl_root)
|
|
return -EBUSY;
|
|
}
|
|
|
|
ret = cgroup_populate_dir(&dst_root->cgrp, ss_mask);
|
|
if (ret) {
|
|
if (dst_root != &cgrp_dfl_root)
|
|
return ret;
|
|
|
|
/*
|
|
* Rebinding back to the default root is not allowed to
|
|
* fail. Using both default and non-default roots should
|
|
* be rare. Moving subsystems back and forth even more so.
|
|
* Just warn about it and continue.
|
|
*/
|
|
if (cgrp_dfl_root_visible) {
|
|
pr_warning("cgroup: failed to create files (%d) while rebinding 0x%lx to default root\n",
|
|
ret, ss_mask);
|
|
pr_warning("cgroup: you may retry by moving them to a different hierarchy and unbinding\n");
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Nothing can fail from this point on. Remove files for the
|
|
* removed subsystems and rebind each subsystem.
|
|
*/
|
|
mutex_unlock(&cgroup_mutex);
|
|
for_each_subsys(ss, ssid)
|
|
if (ss_mask & (1 << ssid))
|
|
cgroup_clear_dir(&ss->root->cgrp, 1 << ssid);
|
|
mutex_lock(&cgroup_mutex);
|
|
|
|
for_each_subsys(ss, ssid) {
|
|
struct cgroup_root *src_root;
|
|
struct cgroup_subsys_state *css;
|
|
|
|
if (!(ss_mask & (1 << ssid)))
|
|
continue;
|
|
|
|
src_root = ss->root;
|
|
css = cgroup_css(&src_root->cgrp, ss);
|
|
|
|
WARN_ON(!css || cgroup_css(&dst_root->cgrp, ss));
|
|
|
|
RCU_INIT_POINTER(src_root->cgrp.subsys[ssid], NULL);
|
|
rcu_assign_pointer(dst_root->cgrp.subsys[ssid], css);
|
|
ss->root = dst_root;
|
|
css->cgroup = &dst_root->cgrp;
|
|
|
|
src_root->cgrp.subsys_mask &= ~(1 << ssid);
|
|
dst_root->cgrp.subsys_mask |= 1 << ssid;
|
|
|
|
if (ss->bind)
|
|
ss->bind(css);
|
|
}
|
|
|
|
kernfs_activate(dst_root->cgrp.kn);
|
|
return 0;
|
|
}
|
|
|
|
static int cgroup_show_options(struct seq_file *seq,
|
|
struct kernfs_root *kf_root)
|
|
{
|
|
struct cgroup_root *root = cgroup_root_from_kf(kf_root);
|
|
struct cgroup_subsys *ss;
|
|
int ssid;
|
|
|
|
for_each_subsys(ss, ssid)
|
|
if (root->cgrp.subsys_mask & (1 << ssid))
|
|
seq_printf(seq, ",%s", ss->name);
|
|
if (root->flags & CGRP_ROOT_SANE_BEHAVIOR)
|
|
seq_puts(seq, ",sane_behavior");
|
|
if (root->flags & CGRP_ROOT_NOPREFIX)
|
|
seq_puts(seq, ",noprefix");
|
|
if (root->flags & CGRP_ROOT_XATTR)
|
|
seq_puts(seq, ",xattr");
|
|
|
|
spin_lock(&release_agent_path_lock);
|
|
if (strlen(root->release_agent_path))
|
|
seq_printf(seq, ",release_agent=%s", root->release_agent_path);
|
|
spin_unlock(&release_agent_path_lock);
|
|
|
|
if (test_bit(CGRP_CPUSET_CLONE_CHILDREN, &root->cgrp.flags))
|
|
seq_puts(seq, ",clone_children");
|
|
if (strlen(root->name))
|
|
seq_printf(seq, ",name=%s", root->name);
|
|
return 0;
|
|
}
|
|
|
|
struct cgroup_sb_opts {
|
|
unsigned long subsys_mask;
|
|
unsigned long flags;
|
|
char *release_agent;
|
|
bool cpuset_clone_children;
|
|
char *name;
|
|
/* User explicitly requested empty subsystem */
|
|
bool none;
|
|
};
|
|
|
|
/*
|
|
* Convert a hierarchy specifier into a bitmask of subsystems and
|
|
* flags. Call with cgroup_mutex held to protect the cgroup_subsys[]
|
|
* array. This function takes refcounts on subsystems to be used, unless it
|
|
* returns error, in which case no refcounts are taken.
|
|
*/
|
|
static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts)
|
|
{
|
|
char *token, *o = data;
|
|
bool all_ss = false, one_ss = false;
|
|
unsigned long mask = (unsigned long)-1;
|
|
struct cgroup_subsys *ss;
|
|
int i;
|
|
|
|
BUG_ON(!mutex_is_locked(&cgroup_mutex));
|
|
|
|
#ifdef CONFIG_CPUSETS
|
|
mask = ~(1UL << cpuset_cgrp_id);
|
|
#endif
|
|
|
|
memset(opts, 0, sizeof(*opts));
|
|
|
|
while ((token = strsep(&o, ",")) != NULL) {
|
|
if (!*token)
|
|
return -EINVAL;
|
|
if (!strcmp(token, "none")) {
|
|
/* Explicitly have no subsystems */
|
|
opts->none = true;
|
|
continue;
|
|
}
|
|
if (!strcmp(token, "all")) {
|
|
/* Mutually exclusive option 'all' + subsystem name */
|
|
if (one_ss)
|
|
return -EINVAL;
|
|
all_ss = true;
|
|
continue;
|
|
}
|
|
if (!strcmp(token, "__DEVEL__sane_behavior")) {
|
|
opts->flags |= CGRP_ROOT_SANE_BEHAVIOR;
|
|
continue;
|
|
}
|
|
if (!strcmp(token, "noprefix")) {
|
|
opts->flags |= CGRP_ROOT_NOPREFIX;
|
|
continue;
|
|
}
|
|
if (!strcmp(token, "clone_children")) {
|
|
opts->cpuset_clone_children = true;
|
|
continue;
|
|
}
|
|
if (!strcmp(token, "xattr")) {
|
|
opts->flags |= CGRP_ROOT_XATTR;
|
|
continue;
|
|
}
|
|
if (!strncmp(token, "release_agent=", 14)) {
|
|
/* Specifying two release agents is forbidden */
|
|
if (opts->release_agent)
|
|
return -EINVAL;
|
|
opts->release_agent =
|
|
kstrndup(token + 14, PATH_MAX - 1, GFP_KERNEL);
|
|
if (!opts->release_agent)
|
|
return -ENOMEM;
|
|
continue;
|
|
}
|
|
if (!strncmp(token, "name=", 5)) {
|
|
const char *name = token + 5;
|
|
/* Can't specify an empty name */
|
|
if (!strlen(name))
|
|
return -EINVAL;
|
|
/* Must match [\w.-]+ */
|
|
for (i = 0; i < strlen(name); i++) {
|
|
char c = name[i];
|
|
if (isalnum(c))
|
|
continue;
|
|
if ((c == '.') || (c == '-') || (c == '_'))
|
|
continue;
|
|
return -EINVAL;
|
|
}
|
|
/* Specifying two names is forbidden */
|
|
if (opts->name)
|
|
return -EINVAL;
|
|
opts->name = kstrndup(name,
|
|
MAX_CGROUP_ROOT_NAMELEN - 1,
|
|
GFP_KERNEL);
|
|
if (!opts->name)
|
|
return -ENOMEM;
|
|
|
|
continue;
|
|
}
|
|
|
|
for_each_subsys(ss, i) {
|
|
if (strcmp(token, ss->name))
|
|
continue;
|
|
if (ss->disabled)
|
|
continue;
|
|
|
|
/* Mutually exclusive option 'all' + subsystem name */
|
|
if (all_ss)
|
|
return -EINVAL;
|
|
set_bit(i, &opts->subsys_mask);
|
|
one_ss = true;
|
|
|
|
break;
|
|
}
|
|
if (i == CGROUP_SUBSYS_COUNT)
|
|
return -ENOENT;
|
|
}
|
|
|
|
/* Consistency checks */
|
|
|
|
if (opts->flags & CGRP_ROOT_SANE_BEHAVIOR) {
|
|
pr_warning("cgroup: sane_behavior: this is still under development and its behaviors will change, proceed at your own risk\n");
|
|
|
|
if ((opts->flags & (CGRP_ROOT_NOPREFIX | CGRP_ROOT_XATTR)) ||
|
|
opts->cpuset_clone_children || opts->release_agent ||
|
|
opts->name) {
|
|
pr_err("cgroup: sane_behavior: noprefix, xattr, clone_children, release_agent and name are not allowed\n");
|
|
return -EINVAL;
|
|
}
|
|
} else {
|
|
/*
|
|
* If the 'all' option was specified select all the
|
|
* subsystems, otherwise if 'none', 'name=' and a subsystem
|
|
* name options were not specified, let's default to 'all'
|
|
*/
|
|
if (all_ss || (!one_ss && !opts->none && !opts->name))
|
|
for_each_subsys(ss, i)
|
|
if (!ss->disabled)
|
|
set_bit(i, &opts->subsys_mask);
|
|
|
|
/*
|
|
* We either have to specify by name or by subsystems. (So
|
|
* all empty hierarchies must have a name).
|
|
*/
|
|
if (!opts->subsys_mask && !opts->name)
|
|
return -EINVAL;
|
|
}
|
|
|
|
/*
|
|
* Option noprefix was introduced just for backward compatibility
|
|
* with the old cpuset, so we allow noprefix only if mounting just
|
|
* the cpuset subsystem.
|
|
*/
|
|
if ((opts->flags & CGRP_ROOT_NOPREFIX) && (opts->subsys_mask & mask))
|
|
return -EINVAL;
|
|
|
|
|
|
/* Can't specify "none" and some subsystems */
|
|
if (opts->subsys_mask && opts->none)
|
|
return -EINVAL;
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int cgroup_remount(struct kernfs_root *kf_root, int *flags, char *data)
|
|
{
|
|
int ret = 0;
|
|
struct cgroup_root *root = cgroup_root_from_kf(kf_root);
|
|
struct cgroup_sb_opts opts;
|
|
unsigned long added_mask, removed_mask;
|
|
|
|
if (root->flags & CGRP_ROOT_SANE_BEHAVIOR) {
|
|
pr_err("cgroup: sane_behavior: remount is not allowed\n");
|
|
return -EINVAL;
|
|
}
|
|
|
|
mutex_lock(&cgroup_tree_mutex);
|
|
mutex_lock(&cgroup_mutex);
|
|
|
|
/* See what subsystems are wanted */
|
|
ret = parse_cgroupfs_options(data, &opts);
|
|
if (ret)
|
|
goto out_unlock;
|
|
|
|
if (opts.subsys_mask != root->cgrp.subsys_mask || opts.release_agent)
|
|
pr_warning("cgroup: option changes via remount are deprecated (pid=%d comm=%s)\n",
|
|
task_tgid_nr(current), current->comm);
|
|
|
|
added_mask = opts.subsys_mask & ~root->cgrp.subsys_mask;
|
|
removed_mask = root->cgrp.subsys_mask & ~opts.subsys_mask;
|
|
|
|
/* Don't allow flags or name to change at remount */
|
|
if (((opts.flags ^ root->flags) & CGRP_ROOT_OPTION_MASK) ||
|
|
(opts.name && strcmp(opts.name, root->name))) {
|
|
pr_err("cgroup: option or name mismatch, new: 0x%lx \"%s\", old: 0x%lx \"%s\"\n",
|
|
opts.flags & CGRP_ROOT_OPTION_MASK, opts.name ?: "",
|
|
root->flags & CGRP_ROOT_OPTION_MASK, root->name);
|
|
ret = -EINVAL;
|
|
goto out_unlock;
|
|
}
|
|
|
|
/* remounting is not allowed for populated hierarchies */
|
|
if (!list_empty(&root->cgrp.children)) {
|
|
ret = -EBUSY;
|
|
goto out_unlock;
|
|
}
|
|
|
|
ret = rebind_subsystems(root, added_mask);
|
|
if (ret)
|
|
goto out_unlock;
|
|
|
|
rebind_subsystems(&cgrp_dfl_root, removed_mask);
|
|
|
|
if (opts.release_agent) {
|
|
spin_lock(&release_agent_path_lock);
|
|
strcpy(root->release_agent_path, opts.release_agent);
|
|
spin_unlock(&release_agent_path_lock);
|
|
}
|
|
out_unlock:
|
|
kfree(opts.release_agent);
|
|
kfree(opts.name);
|
|
mutex_unlock(&cgroup_mutex);
|
|
mutex_unlock(&cgroup_tree_mutex);
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* To reduce the fork() overhead for systems that are not actually using
|
|
* their cgroups capability, we don't maintain the lists running through
|
|
* each css_set to its tasks until we see the list actually used - in other
|
|
* words after the first mount.
|
|
*/
|
|
static bool use_task_css_set_links __read_mostly;
|
|
|
|
static void cgroup_enable_task_cg_lists(void)
|
|
{
|
|
struct task_struct *p, *g;
|
|
|
|
down_write(&css_set_rwsem);
|
|
|
|
if (use_task_css_set_links)
|
|
goto out_unlock;
|
|
|
|
use_task_css_set_links = true;
|
|
|
|
/*
|
|
* We need tasklist_lock because RCU is not safe against
|
|
* while_each_thread(). Besides, a forking task that has passed
|
|
* cgroup_post_fork() without seeing use_task_css_set_links = 1
|
|
* is not guaranteed to have its child immediately visible in the
|
|
* tasklist if we walk through it with RCU.
|
|
*/
|
|
read_lock(&tasklist_lock);
|
|
do_each_thread(g, p) {
|
|
WARN_ON_ONCE(!list_empty(&p->cg_list) ||
|
|
task_css_set(p) != &init_css_set);
|
|
|
|
/*
|
|
* We should check if the process is exiting, otherwise
|
|
* it will race with cgroup_exit() in that the list
|
|
* entry won't be deleted though the process has exited.
|
|
* Do it while holding siglock so that we don't end up
|
|
* racing against cgroup_exit().
|
|
*/
|
|
spin_lock_irq(&p->sighand->siglock);
|
|
if (!(p->flags & PF_EXITING)) {
|
|
struct css_set *cset = task_css_set(p);
|
|
|
|
list_add(&p->cg_list, &cset->tasks);
|
|
get_css_set(cset);
|
|
}
|
|
spin_unlock_irq(&p->sighand->siglock);
|
|
} while_each_thread(g, p);
|
|
read_unlock(&tasklist_lock);
|
|
out_unlock:
|
|
up_write(&css_set_rwsem);
|
|
}
|
|
|
|
static void init_cgroup_housekeeping(struct cgroup *cgrp)
|
|
{
|
|
atomic_set(&cgrp->refcnt, 1);
|
|
INIT_LIST_HEAD(&cgrp->sibling);
|
|
INIT_LIST_HEAD(&cgrp->children);
|
|
INIT_LIST_HEAD(&cgrp->cset_links);
|
|
INIT_LIST_HEAD(&cgrp->release_list);
|
|
INIT_LIST_HEAD(&cgrp->pidlists);
|
|
mutex_init(&cgrp->pidlist_mutex);
|
|
cgrp->dummy_css.cgroup = cgrp;
|
|
}
|
|
|
|
static void init_cgroup_root(struct cgroup_root *root,
|
|
struct cgroup_sb_opts *opts)
|
|
{
|
|
struct cgroup *cgrp = &root->cgrp;
|
|
|
|
INIT_LIST_HEAD(&root->root_list);
|
|
atomic_set(&root->nr_cgrps, 1);
|
|
cgrp->root = root;
|
|
init_cgroup_housekeeping(cgrp);
|
|
idr_init(&root->cgroup_idr);
|
|
|
|
root->flags = opts->flags;
|
|
if (opts->release_agent)
|
|
strcpy(root->release_agent_path, opts->release_agent);
|
|
if (opts->name)
|
|
strcpy(root->name, opts->name);
|
|
if (opts->cpuset_clone_children)
|
|
set_bit(CGRP_CPUSET_CLONE_CHILDREN, &root->cgrp.flags);
|
|
}
|
|
|
|
static int cgroup_setup_root(struct cgroup_root *root, unsigned long ss_mask)
|
|
{
|
|
LIST_HEAD(tmp_links);
|
|
struct cgroup *root_cgrp = &root->cgrp;
|
|
struct css_set *cset;
|
|
int i, ret;
|
|
|
|
lockdep_assert_held(&cgroup_tree_mutex);
|
|
lockdep_assert_held(&cgroup_mutex);
|
|
|
|
ret = idr_alloc(&root->cgroup_idr, root_cgrp, 0, 1, GFP_KERNEL);
|
|
if (ret < 0)
|
|
goto out;
|
|
root_cgrp->id = ret;
|
|
|
|
/*
|
|
* We're accessing css_set_count without locking css_set_rwsem here,
|
|
* but that's OK - it can only be increased by someone holding
|
|
* cgroup_lock, and that's us. The worst that can happen is that we
|
|
* have some link structures left over
|
|
*/
|
|
ret = allocate_cgrp_cset_links(css_set_count, &tmp_links);
|
|
if (ret)
|
|
goto out;
|
|
|
|
ret = cgroup_init_root_id(root);
|
|
if (ret)
|
|
goto out;
|
|
|
|
root->kf_root = kernfs_create_root(&cgroup_kf_syscall_ops,
|
|
KERNFS_ROOT_CREATE_DEACTIVATED,
|
|
root_cgrp);
|
|
if (IS_ERR(root->kf_root)) {
|
|
ret = PTR_ERR(root->kf_root);
|
|
goto exit_root_id;
|
|
}
|
|
root_cgrp->kn = root->kf_root->kn;
|
|
|
|
ret = cgroup_addrm_files(root_cgrp, cgroup_base_files, true);
|
|
if (ret)
|
|
goto destroy_root;
|
|
|
|
ret = rebind_subsystems(root, ss_mask);
|
|
if (ret)
|
|
goto destroy_root;
|
|
|
|
/*
|
|
* There must be no failure case after here, since rebinding takes
|
|
* care of subsystems' refcounts, which are explicitly dropped in
|
|
* the failure exit path.
|
|
*/
|
|
list_add(&root->root_list, &cgroup_roots);
|
|
cgroup_root_count++;
|
|
|
|
/*
|
|
* Link the root cgroup in this hierarchy into all the css_set
|
|
* objects.
|
|
*/
|
|
down_write(&css_set_rwsem);
|
|
hash_for_each(css_set_table, i, cset, hlist)
|
|
link_css_set(&tmp_links, cset, root_cgrp);
|
|
up_write(&css_set_rwsem);
|
|
|
|
BUG_ON(!list_empty(&root_cgrp->children));
|
|
BUG_ON(atomic_read(&root->nr_cgrps) != 1);
|
|
|
|
kernfs_activate(root_cgrp->kn);
|
|
ret = 0;
|
|
goto out;
|
|
|
|
destroy_root:
|
|
kernfs_destroy_root(root->kf_root);
|
|
root->kf_root = NULL;
|
|
exit_root_id:
|
|
cgroup_exit_root_id(root);
|
|
out:
|
|
free_cgrp_cset_links(&tmp_links);
|
|
return ret;
|
|
}
|
|
|
|
static struct dentry *cgroup_mount(struct file_system_type *fs_type,
|
|
int flags, const char *unused_dev_name,
|
|
void *data)
|
|
{
|
|
struct cgroup_root *root;
|
|
struct cgroup_sb_opts opts;
|
|
struct dentry *dentry;
|
|
int ret;
|
|
bool new_sb;
|
|
|
|
/*
|
|
* The first time anyone tries to mount a cgroup, enable the list
|
|
* linking each css_set to its tasks and fix up all existing tasks.
|
|
*/
|
|
if (!use_task_css_set_links)
|
|
cgroup_enable_task_cg_lists();
|
|
retry:
|
|
mutex_lock(&cgroup_tree_mutex);
|
|
mutex_lock(&cgroup_mutex);
|
|
|
|
/* First find the desired set of subsystems */
|
|
ret = parse_cgroupfs_options(data, &opts);
|
|
if (ret)
|
|
goto out_unlock;
|
|
|
|
/* look for a matching existing root */
|
|
if (!opts.subsys_mask && !opts.none && !opts.name) {
|
|
cgrp_dfl_root_visible = true;
|
|
root = &cgrp_dfl_root;
|
|
cgroup_get(&root->cgrp);
|
|
ret = 0;
|
|
goto out_unlock;
|
|
}
|
|
|
|
for_each_root(root) {
|
|
bool name_match = false;
|
|
|
|
if (root == &cgrp_dfl_root)
|
|
continue;
|
|
|
|
/*
|
|
* If we asked for a name then it must match. Also, if
|
|
* name matches but sybsys_mask doesn't, we should fail.
|
|
* Remember whether name matched.
|
|
*/
|
|
if (opts.name) {
|
|
if (strcmp(opts.name, root->name))
|
|
continue;
|
|
name_match = true;
|
|
}
|
|
|
|
/*
|
|
* If we asked for subsystems (or explicitly for no
|
|
* subsystems) then they must match.
|
|
*/
|
|
if ((opts.subsys_mask || opts.none) &&
|
|
(opts.subsys_mask != root->cgrp.subsys_mask)) {
|
|
if (!name_match)
|
|
continue;
|
|
ret = -EBUSY;
|
|
goto out_unlock;
|
|
}
|
|
|
|
if ((root->flags ^ opts.flags) & CGRP_ROOT_OPTION_MASK) {
|
|
if ((root->flags | opts.flags) & CGRP_ROOT_SANE_BEHAVIOR) {
|
|
pr_err("cgroup: sane_behavior: new mount options should match the existing superblock\n");
|
|
ret = -EINVAL;
|
|
goto out_unlock;
|
|
} else {
|
|
pr_warning("cgroup: new mount options do not match the existing superblock, will be ignored\n");
|
|
}
|
|
}
|
|
|
|
/*
|
|
* A root's lifetime is governed by its root cgroup. Zero
|
|
* ref indicate that the root is being destroyed. Wait for
|
|
* destruction to complete so that the subsystems are free.
|
|
* We can use wait_queue for the wait but this path is
|
|
* super cold. Let's just sleep for a bit and retry.
|
|
*/
|
|
if (!atomic_inc_not_zero(&root->cgrp.refcnt)) {
|
|
mutex_unlock(&cgroup_mutex);
|
|
mutex_unlock(&cgroup_tree_mutex);
|
|
kfree(opts.release_agent);
|
|
kfree(opts.name);
|
|
msleep(10);
|
|
goto retry;
|
|
}
|
|
|
|
ret = 0;
|
|
goto out_unlock;
|
|
}
|
|
|
|
/*
|
|
* No such thing, create a new one. name= matching without subsys
|
|
* specification is allowed for already existing hierarchies but we
|
|
* can't create new one without subsys specification.
|
|
*/
|
|
if (!opts.subsys_mask && !opts.none) {
|
|
ret = -EINVAL;
|
|
goto out_unlock;
|
|
}
|
|
|
|
root = kzalloc(sizeof(*root), GFP_KERNEL);
|
|
if (!root) {
|
|
ret = -ENOMEM;
|
|
goto out_unlock;
|
|
}
|
|
|
|
init_cgroup_root(root, &opts);
|
|
|
|
ret = cgroup_setup_root(root, opts.subsys_mask);
|
|
if (ret)
|
|
cgroup_free_root(root);
|
|
|
|
out_unlock:
|
|
mutex_unlock(&cgroup_mutex);
|
|
mutex_unlock(&cgroup_tree_mutex);
|
|
|
|
kfree(opts.release_agent);
|
|
kfree(opts.name);
|
|
|
|
if (ret)
|
|
return ERR_PTR(ret);
|
|
|
|
dentry = kernfs_mount(fs_type, flags, root->kf_root, &new_sb);
|
|
if (IS_ERR(dentry) || !new_sb)
|
|
cgroup_put(&root->cgrp);
|
|
return dentry;
|
|
}
|
|
|
|
static void cgroup_kill_sb(struct super_block *sb)
|
|
{
|
|
struct kernfs_root *kf_root = kernfs_root_from_sb(sb);
|
|
struct cgroup_root *root = cgroup_root_from_kf(kf_root);
|
|
|
|
cgroup_put(&root->cgrp);
|
|
kernfs_kill_sb(sb);
|
|
}
|
|
|
|
static struct file_system_type cgroup_fs_type = {
|
|
.name = "cgroup",
|
|
.mount = cgroup_mount,
|
|
.kill_sb = cgroup_kill_sb,
|
|
};
|
|
|
|
static struct kobject *cgroup_kobj;
|
|
|
|
/**
|
|
* task_cgroup_path - cgroup path of a task in the first cgroup hierarchy
|
|
* @task: target task
|
|
* @buf: the buffer to write the path into
|
|
* @buflen: the length of the buffer
|
|
*
|
|
* Determine @task's cgroup on the first (the one with the lowest non-zero
|
|
* hierarchy_id) cgroup hierarchy and copy its path into @buf. This
|
|
* function grabs cgroup_mutex and shouldn't be used inside locks used by
|
|
* cgroup controller callbacks.
|
|
*
|
|
* Return value is the same as kernfs_path().
|
|
*/
|
|
char *task_cgroup_path(struct task_struct *task, char *buf, size_t buflen)
|
|
{
|
|
struct cgroup_root *root;
|
|
struct cgroup *cgrp;
|
|
int hierarchy_id = 1;
|
|
char *path = NULL;
|
|
|
|
mutex_lock(&cgroup_mutex);
|
|
down_read(&css_set_rwsem);
|
|
|
|
root = idr_get_next(&cgroup_hierarchy_idr, &hierarchy_id);
|
|
|
|
if (root) {
|
|
cgrp = task_cgroup_from_root(task, root);
|
|
path = cgroup_path(cgrp, buf, buflen);
|
|
} else {
|
|
/* if no hierarchy exists, everyone is in "/" */
|
|
if (strlcpy(buf, "/", buflen) < buflen)
|
|
path = buf;
|
|
}
|
|
|
|
up_read(&css_set_rwsem);
|
|
mutex_unlock(&cgroup_mutex);
|
|
return path;
|
|
}
|
|
EXPORT_SYMBOL_GPL(task_cgroup_path);
|
|
|
|
/* used to track tasks and other necessary states during migration */
|
|
struct cgroup_taskset {
|
|
/* the src and dst cset list running through cset->mg_node */
|
|
struct list_head src_csets;
|
|
struct list_head dst_csets;
|
|
|
|
/*
|
|
* Fields for cgroup_taskset_*() iteration.
|
|
*
|
|
* Before migration is committed, the target migration tasks are on
|
|
* ->mg_tasks of the csets on ->src_csets. After, on ->mg_tasks of
|
|
* the csets on ->dst_csets. ->csets point to either ->src_csets
|
|
* or ->dst_csets depending on whether migration is committed.
|
|
*
|
|
* ->cur_csets and ->cur_task point to the current task position
|
|
* during iteration.
|
|
*/
|
|
struct list_head *csets;
|
|
struct css_set *cur_cset;
|
|
struct task_struct *cur_task;
|
|
};
|
|
|
|
/**
|
|
* cgroup_taskset_first - reset taskset and return the first task
|
|
* @tset: taskset of interest
|
|
*
|
|
* @tset iteration is initialized and the first task is returned.
|
|
*/
|
|
struct task_struct *cgroup_taskset_first(struct cgroup_taskset *tset)
|
|
{
|
|
tset->cur_cset = list_first_entry(tset->csets, struct css_set, mg_node);
|
|
tset->cur_task = NULL;
|
|
|
|
return cgroup_taskset_next(tset);
|
|
}
|
|
|
|
/**
|
|
* cgroup_taskset_next - iterate to the next task in taskset
|
|
* @tset: taskset of interest
|
|
*
|
|
* Return the next task in @tset. Iteration must have been initialized
|
|
* with cgroup_taskset_first().
|
|
*/
|
|
struct task_struct *cgroup_taskset_next(struct cgroup_taskset *tset)
|
|
{
|
|
struct css_set *cset = tset->cur_cset;
|
|
struct task_struct *task = tset->cur_task;
|
|
|
|
while (&cset->mg_node != tset->csets) {
|
|
if (!task)
|
|
task = list_first_entry(&cset->mg_tasks,
|
|
struct task_struct, cg_list);
|
|
else
|
|
task = list_next_entry(task, cg_list);
|
|
|
|
if (&task->cg_list != &cset->mg_tasks) {
|
|
tset->cur_cset = cset;
|
|
tset->cur_task = task;
|
|
return task;
|
|
}
|
|
|
|
cset = list_next_entry(cset, mg_node);
|
|
task = NULL;
|
|
}
|
|
|
|
return NULL;
|
|
}
|
|
|
|
/**
|
|
* cgroup_task_migrate - move a task from one cgroup to another.
|
|
* @old_cgrp; the cgroup @tsk is being migrated from
|
|
* @tsk: the task being migrated
|
|
* @new_cset: the new css_set @tsk is being attached to
|
|
*
|
|
* Must be called with cgroup_mutex, threadgroup and css_set_rwsem locked.
|
|
*/
|
|
static void cgroup_task_migrate(struct cgroup *old_cgrp,
|
|
struct task_struct *tsk,
|
|
struct css_set *new_cset)
|
|
{
|
|
struct css_set *old_cset;
|
|
|
|
lockdep_assert_held(&cgroup_mutex);
|
|
lockdep_assert_held(&css_set_rwsem);
|
|
|
|
/*
|
|
* We are synchronized through threadgroup_lock() against PF_EXITING
|
|
* setting such that we can't race against cgroup_exit() changing the
|
|
* css_set to init_css_set and dropping the old one.
|
|
*/
|
|
WARN_ON_ONCE(tsk->flags & PF_EXITING);
|
|
old_cset = task_css_set(tsk);
|
|
|
|
get_css_set(new_cset);
|
|
rcu_assign_pointer(tsk->cgroups, new_cset);
|
|
|
|
/*
|
|
* Use move_tail so that cgroup_taskset_first() still returns the
|
|
* leader after migration. This works because cgroup_migrate()
|
|
* ensures that the dst_cset of the leader is the first on the
|
|
* tset's dst_csets list.
|
|
*/
|
|
list_move_tail(&tsk->cg_list, &new_cset->mg_tasks);
|
|
|
|
/*
|
|
* We just gained a reference on old_cset by taking it from the
|
|
* task. As trading it for new_cset is protected by cgroup_mutex,
|
|
* we're safe to drop it here; it will be freed under RCU.
|
|
*/
|
|
set_bit(CGRP_RELEASABLE, &old_cgrp->flags);
|
|
put_css_set_locked(old_cset, false);
|
|
}
|
|
|
|
/**
|
|
* cgroup_migrate_finish - cleanup after attach
|
|
* @preloaded_csets: list of preloaded css_sets
|
|
*
|
|
* Undo cgroup_migrate_add_src() and cgroup_migrate_prepare_dst(). See
|
|
* those functions for details.
|
|
*/
|
|
static void cgroup_migrate_finish(struct list_head *preloaded_csets)
|
|
{
|
|
struct css_set *cset, *tmp_cset;
|
|
|
|
lockdep_assert_held(&cgroup_mutex);
|
|
|
|
down_write(&css_set_rwsem);
|
|
list_for_each_entry_safe(cset, tmp_cset, preloaded_csets, mg_preload_node) {
|
|
cset->mg_src_cgrp = NULL;
|
|
cset->mg_dst_cset = NULL;
|
|
list_del_init(&cset->mg_preload_node);
|
|
put_css_set_locked(cset, false);
|
|
}
|
|
up_write(&css_set_rwsem);
|
|
}
|
|
|
|
/**
|
|
* cgroup_migrate_add_src - add a migration source css_set
|
|
* @src_cset: the source css_set to add
|
|
* @dst_cgrp: the destination cgroup
|
|
* @preloaded_csets: list of preloaded css_sets
|
|
*
|
|
* Tasks belonging to @src_cset are about to be migrated to @dst_cgrp. Pin
|
|
* @src_cset and add it to @preloaded_csets, which should later be cleaned
|
|
* up by cgroup_migrate_finish().
|
|
*
|
|
* This function may be called without holding threadgroup_lock even if the
|
|
* target is a process. Threads may be created and destroyed but as long
|
|
* as cgroup_mutex is not dropped, no new css_set can be put into play and
|
|
* the preloaded css_sets are guaranteed to cover all migrations.
|
|
*/
|
|
static void cgroup_migrate_add_src(struct css_set *src_cset,
|
|
struct cgroup *dst_cgrp,
|
|
struct list_head *preloaded_csets)
|
|
{
|
|
struct cgroup *src_cgrp;
|
|
|
|
lockdep_assert_held(&cgroup_mutex);
|
|
lockdep_assert_held(&css_set_rwsem);
|
|
|
|
src_cgrp = cset_cgroup_from_root(src_cset, dst_cgrp->root);
|
|
|
|
/* nothing to do if this cset already belongs to the cgroup */
|
|
if (src_cgrp == dst_cgrp)
|
|
return;
|
|
|
|
if (!list_empty(&src_cset->mg_preload_node))
|
|
return;
|
|
|
|
WARN_ON(src_cset->mg_src_cgrp);
|
|
WARN_ON(!list_empty(&src_cset->mg_tasks));
|
|
WARN_ON(!list_empty(&src_cset->mg_node));
|
|
|
|
src_cset->mg_src_cgrp = src_cgrp;
|
|
get_css_set(src_cset);
|
|
list_add(&src_cset->mg_preload_node, preloaded_csets);
|
|
}
|
|
|
|
/**
|
|
* cgroup_migrate_prepare_dst - prepare destination css_sets for migration
|
|
* @dst_cgrp: the destination cgroup
|
|
* @preloaded_csets: list of preloaded source css_sets
|
|
*
|
|
* Tasks are about to be moved to @dst_cgrp and all the source css_sets
|
|
* have been preloaded to @preloaded_csets. This function looks up and
|
|
* pins all destination css_sets, links each to its source, and put them on
|
|
* @preloaded_csets.
|
|
*
|
|
* This function must be called after cgroup_migrate_add_src() has been
|
|
* called on each migration source css_set. After migration is performed
|
|
* using cgroup_migrate(), cgroup_migrate_finish() must be called on
|
|
* @preloaded_csets.
|
|
*/
|
|
static int cgroup_migrate_prepare_dst(struct cgroup *dst_cgrp,
|
|
struct list_head *preloaded_csets)
|
|
{
|
|
LIST_HEAD(csets);
|
|
struct css_set *src_cset;
|
|
|
|
lockdep_assert_held(&cgroup_mutex);
|
|
|
|
/* look up the dst cset for each src cset and link it to src */
|
|
list_for_each_entry(src_cset, preloaded_csets, mg_preload_node) {
|
|
struct css_set *dst_cset;
|
|
|
|
dst_cset = find_css_set(src_cset, dst_cgrp);
|
|
if (!dst_cset)
|
|
goto err;
|
|
|
|
WARN_ON_ONCE(src_cset->mg_dst_cset || dst_cset->mg_dst_cset);
|
|
src_cset->mg_dst_cset = dst_cset;
|
|
|
|
if (list_empty(&dst_cset->mg_preload_node))
|
|
list_add(&dst_cset->mg_preload_node, &csets);
|
|
else
|
|
put_css_set(dst_cset, false);
|
|
}
|
|
|
|
list_splice(&csets, preloaded_csets);
|
|
return 0;
|
|
err:
|
|
cgroup_migrate_finish(&csets);
|
|
return -ENOMEM;
|
|
}
|
|
|
|
/**
|
|
* cgroup_migrate - migrate a process or task to a cgroup
|
|
* @cgrp: the destination cgroup
|
|
* @leader: the leader of the process or the task to migrate
|
|
* @threadgroup: whether @leader points to the whole process or a single task
|
|
*
|
|
* Migrate a process or task denoted by @leader to @cgrp. If migrating a
|
|
* process, the caller must be holding threadgroup_lock of @leader. The
|
|
* caller is also responsible for invoking cgroup_migrate_add_src() and
|
|
* cgroup_migrate_prepare_dst() on the targets before invoking this
|
|
* function and following up with cgroup_migrate_finish().
|
|
*
|
|
* As long as a controller's ->can_attach() doesn't fail, this function is
|
|
* guaranteed to succeed. This means that, excluding ->can_attach()
|
|
* failure, when migrating multiple targets, the success or failure can be
|
|
* decided for all targets by invoking group_migrate_prepare_dst() before
|
|
* actually starting migrating.
|
|
*/
|
|
static int cgroup_migrate(struct cgroup *cgrp, struct task_struct *leader,
|
|
bool threadgroup)
|
|
{
|
|
struct cgroup_taskset tset = {
|
|
.src_csets = LIST_HEAD_INIT(tset.src_csets),
|
|
.dst_csets = LIST_HEAD_INIT(tset.dst_csets),
|
|
.csets = &tset.src_csets,
|
|
};
|
|
struct cgroup_subsys_state *css, *failed_css = NULL;
|
|
struct css_set *cset, *tmp_cset;
|
|
struct task_struct *task, *tmp_task;
|
|
int i, ret;
|
|
|
|
/*
|
|
* Prevent freeing of tasks while we take a snapshot. Tasks that are
|
|
* already PF_EXITING could be freed from underneath us unless we
|
|
* take an rcu_read_lock.
|
|
*/
|
|
down_write(&css_set_rwsem);
|
|
rcu_read_lock();
|
|
task = leader;
|
|
do {
|
|
/* @task either already exited or can't exit until the end */
|
|
if (task->flags & PF_EXITING)
|
|
goto next;
|
|
|
|
/* leave @task alone if post_fork() hasn't linked it yet */
|
|
if (list_empty(&task->cg_list))
|
|
goto next;
|
|
|
|
cset = task_css_set(task);
|
|
if (!cset->mg_src_cgrp)
|
|
goto next;
|
|
|
|
/*
|
|
* cgroup_taskset_first() must always return the leader.
|
|
* Take care to avoid disturbing the ordering.
|
|
*/
|
|
list_move_tail(&task->cg_list, &cset->mg_tasks);
|
|
if (list_empty(&cset->mg_node))
|
|
list_add_tail(&cset->mg_node, &tset.src_csets);
|
|
if (list_empty(&cset->mg_dst_cset->mg_node))
|
|
list_move_tail(&cset->mg_dst_cset->mg_node,
|
|
&tset.dst_csets);
|
|
next:
|
|
if (!threadgroup)
|
|
break;
|
|
} while_each_thread(leader, task);
|
|
rcu_read_unlock();
|
|
up_write(&css_set_rwsem);
|
|
|
|
/* methods shouldn't be called if no task is actually migrating */
|
|
if (list_empty(&tset.src_csets))
|
|
return 0;
|
|
|
|
/* check that we can legitimately attach to the cgroup */
|
|
for_each_css(css, i, cgrp) {
|
|
if (css->ss->can_attach) {
|
|
ret = css->ss->can_attach(css, &tset);
|
|
if (ret) {
|
|
failed_css = css;
|
|
goto out_cancel_attach;
|
|
}
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Now that we're guaranteed success, proceed to move all tasks to
|
|
* the new cgroup. There are no failure cases after here, so this
|
|
* is the commit point.
|
|
*/
|
|
down_write(&css_set_rwsem);
|
|
list_for_each_entry(cset, &tset.src_csets, mg_node) {
|
|
list_for_each_entry_safe(task, tmp_task, &cset->mg_tasks, cg_list)
|
|
cgroup_task_migrate(cset->mg_src_cgrp, task,
|
|
cset->mg_dst_cset);
|
|
}
|
|
up_write(&css_set_rwsem);
|
|
|
|
/*
|
|
* Migration is committed, all target tasks are now on dst_csets.
|
|
* Nothing is sensitive to fork() after this point. Notify
|
|
* controllers that migration is complete.
|
|
*/
|
|
tset.csets = &tset.dst_csets;
|
|
|
|
for_each_css(css, i, cgrp)
|
|
if (css->ss->attach)
|
|
css->ss->attach(css, &tset);
|
|
|
|
ret = 0;
|
|
goto out_release_tset;
|
|
|
|
out_cancel_attach:
|
|
for_each_css(css, i, cgrp) {
|
|
if (css == failed_css)
|
|
break;
|
|
if (css->ss->cancel_attach)
|
|
css->ss->cancel_attach(css, &tset);
|
|
}
|
|
out_release_tset:
|
|
down_write(&css_set_rwsem);
|
|
list_splice_init(&tset.dst_csets, &tset.src_csets);
|
|
list_for_each_entry_safe(cset, tmp_cset, &tset.src_csets, mg_node) {
|
|
list_splice_tail_init(&cset->mg_tasks, &cset->tasks);
|
|
list_del_init(&cset->mg_node);
|
|
}
|
|
up_write(&css_set_rwsem);
|
|
return ret;
|
|
}
|
|
|
|
/**
|
|
* cgroup_attach_task - attach a task or a whole threadgroup to a cgroup
|
|
* @dst_cgrp: the cgroup to attach to
|
|
* @leader: the task or the leader of the threadgroup to be attached
|
|
* @threadgroup: attach the whole threadgroup?
|
|
*
|
|
* Call holding cgroup_mutex and threadgroup_lock of @leader.
|
|
*/
|
|
static int cgroup_attach_task(struct cgroup *dst_cgrp,
|
|
struct task_struct *leader, bool threadgroup)
|
|
{
|
|
LIST_HEAD(preloaded_csets);
|
|
struct task_struct *task;
|
|
int ret;
|
|
|
|
/* look up all src csets */
|
|
down_read(&css_set_rwsem);
|
|
rcu_read_lock();
|
|
task = leader;
|
|
do {
|
|
cgroup_migrate_add_src(task_css_set(task), dst_cgrp,
|
|
&preloaded_csets);
|
|
if (!threadgroup)
|
|
break;
|
|
} while_each_thread(leader, task);
|
|
rcu_read_unlock();
|
|
up_read(&css_set_rwsem);
|
|
|
|
/* prepare dst csets and commit */
|
|
ret = cgroup_migrate_prepare_dst(dst_cgrp, &preloaded_csets);
|
|
if (!ret)
|
|
ret = cgroup_migrate(dst_cgrp, leader, threadgroup);
|
|
|
|
cgroup_migrate_finish(&preloaded_csets);
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* Find the task_struct of the task to attach by vpid and pass it along to the
|
|
* function to attach either it or all tasks in its threadgroup. Will lock
|
|
* cgroup_mutex and threadgroup.
|
|
*/
|
|
static int attach_task_by_pid(struct cgroup *cgrp, u64 pid, bool threadgroup)
|
|
{
|
|
struct task_struct *tsk;
|
|
const struct cred *cred = current_cred(), *tcred;
|
|
int ret;
|
|
|
|
if (!cgroup_lock_live_group(cgrp))
|
|
return -ENODEV;
|
|
|
|
retry_find_task:
|
|
rcu_read_lock();
|
|
if (pid) {
|
|
tsk = find_task_by_vpid(pid);
|
|
if (!tsk) {
|
|
rcu_read_unlock();
|
|
ret = -ESRCH;
|
|
goto out_unlock_cgroup;
|
|
}
|
|
/*
|
|
* even if we're attaching all tasks in the thread group, we
|
|
* only need to check permissions on one of them.
|
|
*/
|
|
tcred = __task_cred(tsk);
|
|
if (!uid_eq(cred->euid, GLOBAL_ROOT_UID) &&
|
|
!uid_eq(cred->euid, tcred->uid) &&
|
|
!uid_eq(cred->euid, tcred->suid)) {
|
|
rcu_read_unlock();
|
|
ret = -EACCES;
|
|
goto out_unlock_cgroup;
|
|
}
|
|
} else
|
|
tsk = current;
|
|
|
|
if (threadgroup)
|
|
tsk = tsk->group_leader;
|
|
|
|
/*
|
|
* Workqueue threads may acquire PF_NO_SETAFFINITY and become
|
|
* trapped in a cpuset, or RT worker may be born in a cgroup
|
|
* with no rt_runtime allocated. Just say no.
|
|
*/
|
|
if (tsk == kthreadd_task || (tsk->flags & PF_NO_SETAFFINITY)) {
|
|
ret = -EINVAL;
|
|
rcu_read_unlock();
|
|
goto out_unlock_cgroup;
|
|
}
|
|
|
|
get_task_struct(tsk);
|
|
rcu_read_unlock();
|
|
|
|
threadgroup_lock(tsk);
|
|
if (threadgroup) {
|
|
if (!thread_group_leader(tsk)) {
|
|
/*
|
|
* a race with de_thread from another thread's exec()
|
|
* may strip us of our leadership, if this happens,
|
|
* there is no choice but to throw this task away and
|
|
* try again; this is
|
|
* "double-double-toil-and-trouble-check locking".
|
|
*/
|
|
threadgroup_unlock(tsk);
|
|
put_task_struct(tsk);
|
|
goto retry_find_task;
|
|
}
|
|
}
|
|
|
|
ret = cgroup_attach_task(cgrp, tsk, threadgroup);
|
|
|
|
threadgroup_unlock(tsk);
|
|
|
|
put_task_struct(tsk);
|
|
out_unlock_cgroup:
|
|
mutex_unlock(&cgroup_mutex);
|
|
return ret;
|
|
}
|
|
|
|
/**
|
|
* cgroup_attach_task_all - attach task 'tsk' to all cgroups of task 'from'
|
|
* @from: attach to all cgroups of a given task
|
|
* @tsk: the task to be attached
|
|
*/
|
|
int cgroup_attach_task_all(struct task_struct *from, struct task_struct *tsk)
|
|
{
|
|
struct cgroup_root *root;
|
|
int retval = 0;
|
|
|
|
mutex_lock(&cgroup_mutex);
|
|
for_each_root(root) {
|
|
struct cgroup *from_cgrp;
|
|
|
|
if (root == &cgrp_dfl_root)
|
|
continue;
|
|
|
|
down_read(&css_set_rwsem);
|
|
from_cgrp = task_cgroup_from_root(from, root);
|
|
up_read(&css_set_rwsem);
|
|
|
|
retval = cgroup_attach_task(from_cgrp, tsk, false);
|
|
if (retval)
|
|
break;
|
|
}
|
|
mutex_unlock(&cgroup_mutex);
|
|
|
|
return retval;
|
|
}
|
|
EXPORT_SYMBOL_GPL(cgroup_attach_task_all);
|
|
|
|
static int cgroup_tasks_write(struct cgroup_subsys_state *css,
|
|
struct cftype *cft, u64 pid)
|
|
{
|
|
return attach_task_by_pid(css->cgroup, pid, false);
|
|
}
|
|
|
|
static int cgroup_procs_write(struct cgroup_subsys_state *css,
|
|
struct cftype *cft, u64 tgid)
|
|
{
|
|
return attach_task_by_pid(css->cgroup, tgid, true);
|
|
}
|
|
|
|
static int cgroup_release_agent_write(struct cgroup_subsys_state *css,
|
|
struct cftype *cft, char *buffer)
|
|
{
|
|
struct cgroup_root *root = css->cgroup->root;
|
|
|
|
BUILD_BUG_ON(sizeof(root->release_agent_path) < PATH_MAX);
|
|
if (!cgroup_lock_live_group(css->cgroup))
|
|
return -ENODEV;
|
|
spin_lock(&release_agent_path_lock);
|
|
strlcpy(root->release_agent_path, buffer,
|
|
sizeof(root->release_agent_path));
|
|
spin_unlock(&release_agent_path_lock);
|
|
mutex_unlock(&cgroup_mutex);
|
|
return 0;
|
|
}
|
|
|
|
static int cgroup_release_agent_show(struct seq_file *seq, void *v)
|
|
{
|
|
struct cgroup *cgrp = seq_css(seq)->cgroup;
|
|
|
|
if (!cgroup_lock_live_group(cgrp))
|
|
return -ENODEV;
|
|
seq_puts(seq, cgrp->root->release_agent_path);
|
|
seq_putc(seq, '\n');
|
|
mutex_unlock(&cgroup_mutex);
|
|
return 0;
|
|
}
|
|
|
|
static int cgroup_sane_behavior_show(struct seq_file *seq, void *v)
|
|
{
|
|
struct cgroup *cgrp = seq_css(seq)->cgroup;
|
|
|
|
seq_printf(seq, "%d\n", cgroup_sane_behavior(cgrp));
|
|
return 0;
|
|
}
|
|
|
|
static ssize_t cgroup_file_write(struct kernfs_open_file *of, char *buf,
|
|
size_t nbytes, loff_t off)
|
|
{
|
|
struct cgroup *cgrp = of->kn->parent->priv;
|
|
struct cftype *cft = of->kn->priv;
|
|
struct cgroup_subsys_state *css;
|
|
int ret;
|
|
|
|
/*
|
|
* kernfs guarantees that a file isn't deleted with operations in
|
|
* flight, which means that the matching css is and stays alive and
|
|
* doesn't need to be pinned. The RCU locking is not necessary
|
|
* either. It's just for the convenience of using cgroup_css().
|
|
*/
|
|
rcu_read_lock();
|
|
css = cgroup_css(cgrp, cft->ss);
|
|
rcu_read_unlock();
|
|
|
|
if (cft->write_string) {
|
|
ret = cft->write_string(css, cft, strstrip(buf));
|
|
} else if (cft->write_u64) {
|
|
unsigned long long v;
|
|
ret = kstrtoull(buf, 0, &v);
|
|
if (!ret)
|
|
ret = cft->write_u64(css, cft, v);
|
|
} else if (cft->write_s64) {
|
|
long long v;
|
|
ret = kstrtoll(buf, 0, &v);
|
|
if (!ret)
|
|
ret = cft->write_s64(css, cft, v);
|
|
} else if (cft->trigger) {
|
|
ret = cft->trigger(css, (unsigned int)cft->private);
|
|
} else {
|
|
ret = -EINVAL;
|
|
}
|
|
|
|
return ret ?: nbytes;
|
|
}
|
|
|
|
static void *cgroup_seqfile_start(struct seq_file *seq, loff_t *ppos)
|
|
{
|
|
return seq_cft(seq)->seq_start(seq, ppos);
|
|
}
|
|
|
|
static void *cgroup_seqfile_next(struct seq_file *seq, void *v, loff_t *ppos)
|
|
{
|
|
return seq_cft(seq)->seq_next(seq, v, ppos);
|
|
}
|
|
|
|
static void cgroup_seqfile_stop(struct seq_file *seq, void *v)
|
|
{
|
|
seq_cft(seq)->seq_stop(seq, v);
|
|
}
|
|
|
|
static int cgroup_seqfile_show(struct seq_file *m, void *arg)
|
|
{
|
|
struct cftype *cft = seq_cft(m);
|
|
struct cgroup_subsys_state *css = seq_css(m);
|
|
|
|
if (cft->seq_show)
|
|
return cft->seq_show(m, arg);
|
|
|
|
if (cft->read_u64)
|
|
seq_printf(m, "%llu\n", cft->read_u64(css, cft));
|
|
else if (cft->read_s64)
|
|
seq_printf(m, "%lld\n", cft->read_s64(css, cft));
|
|
else
|
|
return -EINVAL;
|
|
return 0;
|
|
}
|
|
|
|
static struct kernfs_ops cgroup_kf_single_ops = {
|
|
.atomic_write_len = PAGE_SIZE,
|
|
.write = cgroup_file_write,
|
|
.seq_show = cgroup_seqfile_show,
|
|
};
|
|
|
|
static struct kernfs_ops cgroup_kf_ops = {
|
|
.atomic_write_len = PAGE_SIZE,
|
|
.write = cgroup_file_write,
|
|
.seq_start = cgroup_seqfile_start,
|
|
.seq_next = cgroup_seqfile_next,
|
|
.seq_stop = cgroup_seqfile_stop,
|
|
.seq_show = cgroup_seqfile_show,
|
|
};
|
|
|
|
/*
|
|
* cgroup_rename - Only allow simple rename of directories in place.
|
|
*/
|
|
static int cgroup_rename(struct kernfs_node *kn, struct kernfs_node *new_parent,
|
|
const char *new_name_str)
|
|
{
|
|
struct cgroup *cgrp = kn->priv;
|
|
int ret;
|
|
|
|
if (kernfs_type(kn) != KERNFS_DIR)
|
|
return -ENOTDIR;
|
|
if (kn->parent != new_parent)
|
|
return -EIO;
|
|
|
|
/*
|
|
* This isn't a proper migration and its usefulness is very
|
|
* limited. Disallow if sane_behavior.
|
|
*/
|
|
if (cgroup_sane_behavior(cgrp))
|
|
return -EPERM;
|
|
|
|
/*
|
|
* We're gonna grab cgroup_tree_mutex which nests outside kernfs
|
|
* active_ref. kernfs_rename() doesn't require active_ref
|
|
* protection. Break them before grabbing cgroup_tree_mutex.
|
|
*/
|
|
kernfs_break_active_protection(new_parent);
|
|
kernfs_break_active_protection(kn);
|
|
|
|
mutex_lock(&cgroup_tree_mutex);
|
|
mutex_lock(&cgroup_mutex);
|
|
|
|
ret = kernfs_rename(kn, new_parent, new_name_str);
|
|
|
|
mutex_unlock(&cgroup_mutex);
|
|
mutex_unlock(&cgroup_tree_mutex);
|
|
|
|
kernfs_unbreak_active_protection(kn);
|
|
kernfs_unbreak_active_protection(new_parent);
|
|
return ret;
|
|
}
|
|
|
|
/* set uid and gid of cgroup dirs and files to that of the creator */
|
|
static int cgroup_kn_set_ugid(struct kernfs_node *kn)
|
|
{
|
|
struct iattr iattr = { .ia_valid = ATTR_UID | ATTR_GID,
|
|
.ia_uid = current_fsuid(),
|
|
.ia_gid = current_fsgid(), };
|
|
|
|
if (uid_eq(iattr.ia_uid, GLOBAL_ROOT_UID) &&
|
|
gid_eq(iattr.ia_gid, GLOBAL_ROOT_GID))
|
|
return 0;
|
|
|
|
return kernfs_setattr(kn, &iattr);
|
|
}
|
|
|
|
static int cgroup_add_file(struct cgroup *cgrp, struct cftype *cft)
|
|
{
|
|
char name[CGROUP_FILE_NAME_MAX];
|
|
struct kernfs_node *kn;
|
|
struct lock_class_key *key = NULL;
|
|
int ret;
|
|
|
|
#ifdef CONFIG_DEBUG_LOCK_ALLOC
|
|
key = &cft->lockdep_key;
|
|
#endif
|
|
kn = __kernfs_create_file(cgrp->kn, cgroup_file_name(cgrp, cft, name),
|
|
cgroup_file_mode(cft), 0, cft->kf_ops, cft,
|
|
NULL, false, key);
|
|
if (IS_ERR(kn))
|
|
return PTR_ERR(kn);
|
|
|
|
ret = cgroup_kn_set_ugid(kn);
|
|
if (ret)
|
|
kernfs_remove(kn);
|
|
return ret;
|
|
}
|
|
|
|
/**
|
|
* cgroup_addrm_files - add or remove files to a cgroup directory
|
|
* @cgrp: the target cgroup
|
|
* @cfts: array of cftypes to be added
|
|
* @is_add: whether to add or remove
|
|
*
|
|
* Depending on @is_add, add or remove files defined by @cfts on @cgrp.
|
|
* For removals, this function never fails. If addition fails, this
|
|
* function doesn't remove files already added. The caller is responsible
|
|
* for cleaning up.
|
|
*/
|
|
static int cgroup_addrm_files(struct cgroup *cgrp, struct cftype cfts[],
|
|
bool is_add)
|
|
{
|
|
struct cftype *cft;
|
|
int ret;
|
|
|
|
lockdep_assert_held(&cgroup_tree_mutex);
|
|
|
|
for (cft = cfts; cft->name[0] != '\0'; cft++) {
|
|
/* does cft->flags tell us to skip this file on @cgrp? */
|
|
if ((cft->flags & CFTYPE_ONLY_ON_DFL) && !cgroup_on_dfl(cgrp))
|
|
continue;
|
|
if ((cft->flags & CFTYPE_INSANE) && cgroup_sane_behavior(cgrp))
|
|
continue;
|
|
if ((cft->flags & CFTYPE_NOT_ON_ROOT) && !cgrp->parent)
|
|
continue;
|
|
if ((cft->flags & CFTYPE_ONLY_ON_ROOT) && cgrp->parent)
|
|
continue;
|
|
|
|
if (is_add) {
|
|
ret = cgroup_add_file(cgrp, cft);
|
|
if (ret) {
|
|
pr_warn("cgroup_addrm_files: failed to add %s, err=%d\n",
|
|
cft->name, ret);
|
|
return ret;
|
|
}
|
|
} else {
|
|
cgroup_rm_file(cgrp, cft);
|
|
}
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
static int cgroup_apply_cftypes(struct cftype *cfts, bool is_add)
|
|
{
|
|
LIST_HEAD(pending);
|
|
struct cgroup_subsys *ss = cfts[0].ss;
|
|
struct cgroup *root = &ss->root->cgrp;
|
|
struct cgroup_subsys_state *css;
|
|
int ret = 0;
|
|
|
|
lockdep_assert_held(&cgroup_tree_mutex);
|
|
|
|
/* don't bother if @ss isn't attached */
|
|
if (ss->root == &cgrp_dfl_root)
|
|
return 0;
|
|
|
|
/* add/rm files for all cgroups created before */
|
|
css_for_each_descendant_pre(css, cgroup_css(root, ss)) {
|
|
struct cgroup *cgrp = css->cgroup;
|
|
|
|
if (cgroup_is_dead(cgrp))
|
|
continue;
|
|
|
|
ret = cgroup_addrm_files(cgrp, cfts, is_add);
|
|
if (ret)
|
|
break;
|
|
}
|
|
|
|
if (is_add && !ret)
|
|
kernfs_activate(root->kn);
|
|
return ret;
|
|
}
|
|
|
|
static void cgroup_exit_cftypes(struct cftype *cfts)
|
|
{
|
|
struct cftype *cft;
|
|
|
|
for (cft = cfts; cft->name[0] != '\0'; cft++) {
|
|
/* free copy for custom atomic_write_len, see init_cftypes() */
|
|
if (cft->max_write_len && cft->max_write_len != PAGE_SIZE)
|
|
kfree(cft->kf_ops);
|
|
cft->kf_ops = NULL;
|
|
cft->ss = NULL;
|
|
}
|
|
}
|
|
|
|
static int cgroup_init_cftypes(struct cgroup_subsys *ss, struct cftype *cfts)
|
|
{
|
|
struct cftype *cft;
|
|
|
|
for (cft = cfts; cft->name[0] != '\0'; cft++) {
|
|
struct kernfs_ops *kf_ops;
|
|
|
|
WARN_ON(cft->ss || cft->kf_ops);
|
|
|
|
if (cft->seq_start)
|
|
kf_ops = &cgroup_kf_ops;
|
|
else
|
|
kf_ops = &cgroup_kf_single_ops;
|
|
|
|
/*
|
|
* Ugh... if @cft wants a custom max_write_len, we need to
|
|
* make a copy of kf_ops to set its atomic_write_len.
|
|
*/
|
|
if (cft->max_write_len && cft->max_write_len != PAGE_SIZE) {
|
|
kf_ops = kmemdup(kf_ops, sizeof(*kf_ops), GFP_KERNEL);
|
|
if (!kf_ops) {
|
|
cgroup_exit_cftypes(cfts);
|
|
return -ENOMEM;
|
|
}
|
|
kf_ops->atomic_write_len = cft->max_write_len;
|
|
}
|
|
|
|
cft->kf_ops = kf_ops;
|
|
cft->ss = ss;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int cgroup_rm_cftypes_locked(struct cftype *cfts)
|
|
{
|
|
lockdep_assert_held(&cgroup_tree_mutex);
|
|
|
|
if (!cfts || !cfts[0].ss)
|
|
return -ENOENT;
|
|
|
|
list_del(&cfts->node);
|
|
cgroup_apply_cftypes(cfts, false);
|
|
cgroup_exit_cftypes(cfts);
|
|
return 0;
|
|
}
|
|
|
|
/**
|
|
* cgroup_rm_cftypes - remove an array of cftypes from a subsystem
|
|
* @cfts: zero-length name terminated array of cftypes
|
|
*
|
|
* Unregister @cfts. Files described by @cfts are removed from all
|
|
* existing cgroups and all future cgroups won't have them either. This
|
|
* function can be called anytime whether @cfts' subsys is attached or not.
|
|
*
|
|
* Returns 0 on successful unregistration, -ENOENT if @cfts is not
|
|
* registered.
|
|
*/
|
|
int cgroup_rm_cftypes(struct cftype *cfts)
|
|
{
|
|
int ret;
|
|
|
|
mutex_lock(&cgroup_tree_mutex);
|
|
ret = cgroup_rm_cftypes_locked(cfts);
|
|
mutex_unlock(&cgroup_tree_mutex);
|
|
return ret;
|
|
}
|
|
|
|
/**
|
|
* cgroup_add_cftypes - add an array of cftypes to a subsystem
|
|
* @ss: target cgroup subsystem
|
|
* @cfts: zero-length name terminated array of cftypes
|
|
*
|
|
* Register @cfts to @ss. Files described by @cfts are created for all
|
|
* existing cgroups to which @ss is attached and all future cgroups will
|
|
* have them too. This function can be called anytime whether @ss is
|
|
* attached or not.
|
|
*
|
|
* Returns 0 on successful registration, -errno on failure. Note that this
|
|
* function currently returns 0 as long as @cfts registration is successful
|
|
* even if some file creation attempts on existing cgroups fail.
|
|
*/
|
|
int cgroup_add_cftypes(struct cgroup_subsys *ss, struct cftype *cfts)
|
|
{
|
|
int ret;
|
|
|
|
if (!cfts || cfts[0].name[0] == '\0')
|
|
return 0;
|
|
|
|
ret = cgroup_init_cftypes(ss, cfts);
|
|
if (ret)
|
|
return ret;
|
|
|
|
mutex_lock(&cgroup_tree_mutex);
|
|
|
|
list_add_tail(&cfts->node, &ss->cfts);
|
|
ret = cgroup_apply_cftypes(cfts, true);
|
|
if (ret)
|
|
cgroup_rm_cftypes_locked(cfts);
|
|
|
|
mutex_unlock(&cgroup_tree_mutex);
|
|
return ret;
|
|
}
|
|
|
|
/**
|
|
* cgroup_task_count - count the number of tasks in a cgroup.
|
|
* @cgrp: the cgroup in question
|
|
*
|
|
* Return the number of tasks in the cgroup.
|
|
*/
|
|
static int cgroup_task_count(const struct cgroup *cgrp)
|
|
{
|
|
int count = 0;
|
|
struct cgrp_cset_link *link;
|
|
|
|
down_read(&css_set_rwsem);
|
|
list_for_each_entry(link, &cgrp->cset_links, cset_link)
|
|
count += atomic_read(&link->cset->refcount);
|
|
up_read(&css_set_rwsem);
|
|
return count;
|
|
}
|
|
|
|
/**
|
|
* css_next_child - find the next child of a given css
|
|
* @pos_css: the current position (%NULL to initiate traversal)
|
|
* @parent_css: css whose children to walk
|
|
*
|
|
* This function returns the next child of @parent_css and should be called
|
|
* under either cgroup_mutex or RCU read lock. The only requirement is
|
|
* that @parent_css and @pos_css are accessible. The next sibling is
|
|
* guaranteed to be returned regardless of their states.
|
|
*/
|
|
struct cgroup_subsys_state *
|
|
css_next_child(struct cgroup_subsys_state *pos_css,
|
|
struct cgroup_subsys_state *parent_css)
|
|
{
|
|
struct cgroup *pos = pos_css ? pos_css->cgroup : NULL;
|
|
struct cgroup *cgrp = parent_css->cgroup;
|
|
struct cgroup *next;
|
|
|
|
cgroup_assert_mutexes_or_rcu_locked();
|
|
|
|
/*
|
|
* @pos could already have been removed. Once a cgroup is removed,
|
|
* its ->sibling.next is no longer updated when its next sibling
|
|
* changes. As CGRP_DEAD assertion is serialized and happens
|
|
* before the cgroup is taken off the ->sibling list, if we see it
|
|
* unasserted, it's guaranteed that the next sibling hasn't
|
|
* finished its grace period even if it's already removed, and thus
|
|
* safe to dereference from this RCU critical section. If
|
|
* ->sibling.next is inaccessible, cgroup_is_dead() is guaranteed
|
|
* to be visible as %true here.
|
|
*
|
|
* If @pos is dead, its next pointer can't be dereferenced;
|
|
* however, as each cgroup is given a monotonically increasing
|
|
* unique serial number and always appended to the sibling list,
|
|
* the next one can be found by walking the parent's children until
|
|
* we see a cgroup with higher serial number than @pos's. While
|
|
* this path can be slower, it's taken only when either the current
|
|
* cgroup is removed or iteration and removal race.
|
|
*/
|
|
if (!pos) {
|
|
next = list_entry_rcu(cgrp->children.next, struct cgroup, sibling);
|
|
} else if (likely(!cgroup_is_dead(pos))) {
|
|
next = list_entry_rcu(pos->sibling.next, struct cgroup, sibling);
|
|
} else {
|
|
list_for_each_entry_rcu(next, &cgrp->children, sibling)
|
|
if (next->serial_nr > pos->serial_nr)
|
|
break;
|
|
}
|
|
|
|
if (&next->sibling == &cgrp->children)
|
|
return NULL;
|
|
|
|
return cgroup_css(next, parent_css->ss);
|
|
}
|
|
|
|
/**
|
|
* css_next_descendant_pre - find the next descendant for pre-order walk
|
|
* @pos: the current position (%NULL to initiate traversal)
|
|
* @root: css whose descendants to walk
|
|
*
|
|
* To be used by css_for_each_descendant_pre(). Find the next descendant
|
|
* to visit for pre-order traversal of @root's descendants. @root is
|
|
* included in the iteration and the first node to be visited.
|
|
*
|
|
* While this function requires cgroup_mutex or RCU read locking, it
|
|
* doesn't require the whole traversal to be contained in a single critical
|
|
* section. This function will return the correct next descendant as long
|
|
* as both @pos and @root are accessible and @pos is a descendant of @root.
|
|
*/
|
|
struct cgroup_subsys_state *
|
|
css_next_descendant_pre(struct cgroup_subsys_state *pos,
|
|
struct cgroup_subsys_state *root)
|
|
{
|
|
struct cgroup_subsys_state *next;
|
|
|
|
cgroup_assert_mutexes_or_rcu_locked();
|
|
|
|
/* if first iteration, visit @root */
|
|
if (!pos)
|
|
return root;
|
|
|
|
/* visit the first child if exists */
|
|
next = css_next_child(NULL, pos);
|
|
if (next)
|
|
return next;
|
|
|
|
/* no child, visit my or the closest ancestor's next sibling */
|
|
while (pos != root) {
|
|
next = css_next_child(pos, css_parent(pos));
|
|
if (next)
|
|
return next;
|
|
pos = css_parent(pos);
|
|
}
|
|
|
|
return NULL;
|
|
}
|
|
|
|
/**
|
|
* css_rightmost_descendant - return the rightmost descendant of a css
|
|
* @pos: css of interest
|
|
*
|
|
* Return the rightmost descendant of @pos. If there's no descendant, @pos
|
|
* is returned. This can be used during pre-order traversal to skip
|
|
* subtree of @pos.
|
|
*
|
|
* While this function requires cgroup_mutex or RCU read locking, it
|
|
* doesn't require the whole traversal to be contained in a single critical
|
|
* section. This function will return the correct rightmost descendant as
|
|
* long as @pos is accessible.
|
|
*/
|
|
struct cgroup_subsys_state *
|
|
css_rightmost_descendant(struct cgroup_subsys_state *pos)
|
|
{
|
|
struct cgroup_subsys_state *last, *tmp;
|
|
|
|
cgroup_assert_mutexes_or_rcu_locked();
|
|
|
|
do {
|
|
last = pos;
|
|
/* ->prev isn't RCU safe, walk ->next till the end */
|
|
pos = NULL;
|
|
css_for_each_child(tmp, last)
|
|
pos = tmp;
|
|
} while (pos);
|
|
|
|
return last;
|
|
}
|
|
|
|
static struct cgroup_subsys_state *
|
|
css_leftmost_descendant(struct cgroup_subsys_state *pos)
|
|
{
|
|
struct cgroup_subsys_state *last;
|
|
|
|
do {
|
|
last = pos;
|
|
pos = css_next_child(NULL, pos);
|
|
} while (pos);
|
|
|
|
return last;
|
|
}
|
|
|
|
/**
|
|
* css_next_descendant_post - find the next descendant for post-order walk
|
|
* @pos: the current position (%NULL to initiate traversal)
|
|
* @root: css whose descendants to walk
|
|
*
|
|
* To be used by css_for_each_descendant_post(). Find the next descendant
|
|
* to visit for post-order traversal of @root's descendants. @root is
|
|
* included in the iteration and the last node to be visited.
|
|
*
|
|
* While this function requires cgroup_mutex or RCU read locking, it
|
|
* doesn't require the whole traversal to be contained in a single critical
|
|
* section. This function will return the correct next descendant as long
|
|
* as both @pos and @cgroup are accessible and @pos is a descendant of
|
|
* @cgroup.
|
|
*/
|
|
struct cgroup_subsys_state *
|
|
css_next_descendant_post(struct cgroup_subsys_state *pos,
|
|
struct cgroup_subsys_state *root)
|
|
{
|
|
struct cgroup_subsys_state *next;
|
|
|
|
cgroup_assert_mutexes_or_rcu_locked();
|
|
|
|
/* if first iteration, visit leftmost descendant which may be @root */
|
|
if (!pos)
|
|
return css_leftmost_descendant(root);
|
|
|
|
/* if we visited @root, we're done */
|
|
if (pos == root)
|
|
return NULL;
|
|
|
|
/* if there's an unvisited sibling, visit its leftmost descendant */
|
|
next = css_next_child(pos, css_parent(pos));
|
|
if (next)
|
|
return css_leftmost_descendant(next);
|
|
|
|
/* no sibling left, visit parent */
|
|
return css_parent(pos);
|
|
}
|
|
|
|
/**
|
|
* css_advance_task_iter - advance a task itererator to the next css_set
|
|
* @it: the iterator to advance
|
|
*
|
|
* Advance @it to the next css_set to walk.
|
|
*/
|
|
static void css_advance_task_iter(struct css_task_iter *it)
|
|
{
|
|
struct list_head *l = it->cset_link;
|
|
struct cgrp_cset_link *link;
|
|
struct css_set *cset;
|
|
|
|
/* Advance to the next non-empty css_set */
|
|
do {
|
|
l = l->next;
|
|
if (l == &it->origin_css->cgroup->cset_links) {
|
|
it->cset_link = NULL;
|
|
return;
|
|
}
|
|
link = list_entry(l, struct cgrp_cset_link, cset_link);
|
|
cset = link->cset;
|
|
} while (list_empty(&cset->tasks) && list_empty(&cset->mg_tasks));
|
|
|
|
it->cset_link = l;
|
|
|
|
if (!list_empty(&cset->tasks))
|
|
it->task = cset->tasks.next;
|
|
else
|
|
it->task = cset->mg_tasks.next;
|
|
}
|
|
|
|
/**
|
|
* css_task_iter_start - initiate task iteration
|
|
* @css: the css to walk tasks of
|
|
* @it: the task iterator to use
|
|
*
|
|
* Initiate iteration through the tasks of @css. The caller can call
|
|
* css_task_iter_next() to walk through the tasks until the function
|
|
* returns NULL. On completion of iteration, css_task_iter_end() must be
|
|
* called.
|
|
*
|
|
* Note that this function acquires a lock which is released when the
|
|
* iteration finishes. The caller can't sleep while iteration is in
|
|
* progress.
|
|
*/
|
|
void css_task_iter_start(struct cgroup_subsys_state *css,
|
|
struct css_task_iter *it)
|
|
__acquires(css_set_rwsem)
|
|
{
|
|
/* no one should try to iterate before mounting cgroups */
|
|
WARN_ON_ONCE(!use_task_css_set_links);
|
|
|
|
down_read(&css_set_rwsem);
|
|
|
|
it->origin_css = css;
|
|
it->cset_link = &css->cgroup->cset_links;
|
|
|
|
css_advance_task_iter(it);
|
|
}
|
|
|
|
/**
|
|
* css_task_iter_next - return the next task for the iterator
|
|
* @it: the task iterator being iterated
|
|
*
|
|
* The "next" function for task iteration. @it should have been
|
|
* initialized via css_task_iter_start(). Returns NULL when the iteration
|
|
* reaches the end.
|
|
*/
|
|
struct task_struct *css_task_iter_next(struct css_task_iter *it)
|
|
{
|
|
struct task_struct *res;
|
|
struct list_head *l = it->task;
|
|
struct cgrp_cset_link *link = list_entry(it->cset_link,
|
|
struct cgrp_cset_link, cset_link);
|
|
|
|
/* If the iterator cg is NULL, we have no tasks */
|
|
if (!it->cset_link)
|
|
return NULL;
|
|
res = list_entry(l, struct task_struct, cg_list);
|
|
|
|
/*
|
|
* Advance iterator to find next entry. cset->tasks is consumed
|
|
* first and then ->mg_tasks. After ->mg_tasks, we move onto the
|
|
* next cset.
|
|
*/
|
|
l = l->next;
|
|
|
|
if (l == &link->cset->tasks)
|
|
l = link->cset->mg_tasks.next;
|
|
|
|
if (l == &link->cset->mg_tasks)
|
|
css_advance_task_iter(it);
|
|
else
|
|
it->task = l;
|
|
|
|
return res;
|
|
}
|
|
|
|
/**
|
|
* css_task_iter_end - finish task iteration
|
|
* @it: the task iterator to finish
|
|
*
|
|
* Finish task iteration started by css_task_iter_start().
|
|
*/
|
|
void css_task_iter_end(struct css_task_iter *it)
|
|
__releases(css_set_rwsem)
|
|
{
|
|
up_read(&css_set_rwsem);
|
|
}
|
|
|
|
/**
|
|
* cgroup_trasnsfer_tasks - move tasks from one cgroup to another
|
|
* @to: cgroup to which the tasks will be moved
|
|
* @from: cgroup in which the tasks currently reside
|
|
*
|
|
* Locking rules between cgroup_post_fork() and the migration path
|
|
* guarantee that, if a task is forking while being migrated, the new child
|
|
* is guaranteed to be either visible in the source cgroup after the
|
|
* parent's migration is complete or put into the target cgroup. No task
|
|
* can slip out of migration through forking.
|
|
*/
|
|
int cgroup_transfer_tasks(struct cgroup *to, struct cgroup *from)
|
|
{
|
|
LIST_HEAD(preloaded_csets);
|
|
struct cgrp_cset_link *link;
|
|
struct css_task_iter it;
|
|
struct task_struct *task;
|
|
int ret;
|
|
|
|
mutex_lock(&cgroup_mutex);
|
|
|
|
/* all tasks in @from are being moved, all csets are source */
|
|
down_read(&css_set_rwsem);
|
|
list_for_each_entry(link, &from->cset_links, cset_link)
|
|
cgroup_migrate_add_src(link->cset, to, &preloaded_csets);
|
|
up_read(&css_set_rwsem);
|
|
|
|
ret = cgroup_migrate_prepare_dst(to, &preloaded_csets);
|
|
if (ret)
|
|
goto out_err;
|
|
|
|
/*
|
|
* Migrate tasks one-by-one until @form is empty. This fails iff
|
|
* ->can_attach() fails.
|
|
*/
|
|
do {
|
|
css_task_iter_start(&from->dummy_css, &it);
|
|
task = css_task_iter_next(&it);
|
|
if (task)
|
|
get_task_struct(task);
|
|
css_task_iter_end(&it);
|
|
|
|
if (task) {
|
|
ret = cgroup_migrate(to, task, false);
|
|
put_task_struct(task);
|
|
}
|
|
} while (task && !ret);
|
|
out_err:
|
|
cgroup_migrate_finish(&preloaded_csets);
|
|
mutex_unlock(&cgroup_mutex);
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* Stuff for reading the 'tasks'/'procs' files.
|
|
*
|
|
* Reading this file can return large amounts of data if a cgroup has
|
|
* *lots* of attached tasks. So it may need several calls to read(),
|
|
* but we cannot guarantee that the information we produce is correct
|
|
* unless we produce it entirely atomically.
|
|
*
|
|
*/
|
|
|
|
/* which pidlist file are we talking about? */
|
|
enum cgroup_filetype {
|
|
CGROUP_FILE_PROCS,
|
|
CGROUP_FILE_TASKS,
|
|
};
|
|
|
|
/*
|
|
* A pidlist is a list of pids that virtually represents the contents of one
|
|
* of the cgroup files ("procs" or "tasks"). We keep a list of such pidlists,
|
|
* a pair (one each for procs, tasks) for each pid namespace that's relevant
|
|
* to the cgroup.
|
|
*/
|
|
struct cgroup_pidlist {
|
|
/*
|
|
* used to find which pidlist is wanted. doesn't change as long as
|
|
* this particular list stays in the list.
|
|
*/
|
|
struct { enum cgroup_filetype type; struct pid_namespace *ns; } key;
|
|
/* array of xids */
|
|
pid_t *list;
|
|
/* how many elements the above list has */
|
|
int length;
|
|
/* each of these stored in a list by its cgroup */
|
|
struct list_head links;
|
|
/* pointer to the cgroup we belong to, for list removal purposes */
|
|
struct cgroup *owner;
|
|
/* for delayed destruction */
|
|
struct delayed_work destroy_dwork;
|
|
};
|
|
|
|
/*
|
|
* The following two functions "fix" the issue where there are more pids
|
|
* than kmalloc will give memory for; in such cases, we use vmalloc/vfree.
|
|
* TODO: replace with a kernel-wide solution to this problem
|
|
*/
|
|
#define PIDLIST_TOO_LARGE(c) ((c) * sizeof(pid_t) > (PAGE_SIZE * 2))
|
|
static void *pidlist_allocate(int count)
|
|
{
|
|
if (PIDLIST_TOO_LARGE(count))
|
|
return vmalloc(count * sizeof(pid_t));
|
|
else
|
|
return kmalloc(count * sizeof(pid_t), GFP_KERNEL);
|
|
}
|
|
|
|
static void pidlist_free(void *p)
|
|
{
|
|
if (is_vmalloc_addr(p))
|
|
vfree(p);
|
|
else
|
|
kfree(p);
|
|
}
|
|
|
|
/*
|
|
* Used to destroy all pidlists lingering waiting for destroy timer. None
|
|
* should be left afterwards.
|
|
*/
|
|
static void cgroup_pidlist_destroy_all(struct cgroup *cgrp)
|
|
{
|
|
struct cgroup_pidlist *l, *tmp_l;
|
|
|
|
mutex_lock(&cgrp->pidlist_mutex);
|
|
list_for_each_entry_safe(l, tmp_l, &cgrp->pidlists, links)
|
|
mod_delayed_work(cgroup_pidlist_destroy_wq, &l->destroy_dwork, 0);
|
|
mutex_unlock(&cgrp->pidlist_mutex);
|
|
|
|
flush_workqueue(cgroup_pidlist_destroy_wq);
|
|
BUG_ON(!list_empty(&cgrp->pidlists));
|
|
}
|
|
|
|
static void cgroup_pidlist_destroy_work_fn(struct work_struct *work)
|
|
{
|
|
struct delayed_work *dwork = to_delayed_work(work);
|
|
struct cgroup_pidlist *l = container_of(dwork, struct cgroup_pidlist,
|
|
destroy_dwork);
|
|
struct cgroup_pidlist *tofree = NULL;
|
|
|
|
mutex_lock(&l->owner->pidlist_mutex);
|
|
|
|
/*
|
|
* Destroy iff we didn't get queued again. The state won't change
|
|
* as destroy_dwork can only be queued while locked.
|
|
*/
|
|
if (!delayed_work_pending(dwork)) {
|
|
list_del(&l->links);
|
|
pidlist_free(l->list);
|
|
put_pid_ns(l->key.ns);
|
|
tofree = l;
|
|
}
|
|
|
|
mutex_unlock(&l->owner->pidlist_mutex);
|
|
kfree(tofree);
|
|
}
|
|
|
|
/*
|
|
* pidlist_uniq - given a kmalloc()ed list, strip out all duplicate entries
|
|
* Returns the number of unique elements.
|
|
*/
|
|
static int pidlist_uniq(pid_t *list, int length)
|
|
{
|
|
int src, dest = 1;
|
|
|
|
/*
|
|
* we presume the 0th element is unique, so i starts at 1. trivial
|
|
* edge cases first; no work needs to be done for either
|
|
*/
|
|
if (length == 0 || length == 1)
|
|
return length;
|
|
/* src and dest walk down the list; dest counts unique elements */
|
|
for (src = 1; src < length; src++) {
|
|
/* find next unique element */
|
|
while (list[src] == list[src-1]) {
|
|
src++;
|
|
if (src == length)
|
|
goto after;
|
|
}
|
|
/* dest always points to where the next unique element goes */
|
|
list[dest] = list[src];
|
|
dest++;
|
|
}
|
|
after:
|
|
return dest;
|
|
}
|
|
|
|
/*
|
|
* The two pid files - task and cgroup.procs - guaranteed that the result
|
|
* is sorted, which forced this whole pidlist fiasco. As pid order is
|
|
* different per namespace, each namespace needs differently sorted list,
|
|
* making it impossible to use, for example, single rbtree of member tasks
|
|
* sorted by task pointer. As pidlists can be fairly large, allocating one
|
|
* per open file is dangerous, so cgroup had to implement shared pool of
|
|
* pidlists keyed by cgroup and namespace.
|
|
*
|
|
* All this extra complexity was caused by the original implementation
|
|
* committing to an entirely unnecessary property. In the long term, we
|
|
* want to do away with it. Explicitly scramble sort order if
|
|
* sane_behavior so that no such expectation exists in the new interface.
|
|
*
|
|
* Scrambling is done by swapping every two consecutive bits, which is
|
|
* non-identity one-to-one mapping which disturbs sort order sufficiently.
|
|
*/
|
|
static pid_t pid_fry(pid_t pid)
|
|
{
|
|
unsigned a = pid & 0x55555555;
|
|
unsigned b = pid & 0xAAAAAAAA;
|
|
|
|
return (a << 1) | (b >> 1);
|
|
}
|
|
|
|
static pid_t cgroup_pid_fry(struct cgroup *cgrp, pid_t pid)
|
|
{
|
|
if (cgroup_sane_behavior(cgrp))
|
|
return pid_fry(pid);
|
|
else
|
|
return pid;
|
|
}
|
|
|
|
static int cmppid(const void *a, const void *b)
|
|
{
|
|
return *(pid_t *)a - *(pid_t *)b;
|
|
}
|
|
|
|
static int fried_cmppid(const void *a, const void *b)
|
|
{
|
|
return pid_fry(*(pid_t *)a) - pid_fry(*(pid_t *)b);
|
|
}
|
|
|
|
static struct cgroup_pidlist *cgroup_pidlist_find(struct cgroup *cgrp,
|
|
enum cgroup_filetype type)
|
|
{
|
|
struct cgroup_pidlist *l;
|
|
/* don't need task_nsproxy() if we're looking at ourself */
|
|
struct pid_namespace *ns = task_active_pid_ns(current);
|
|
|
|
lockdep_assert_held(&cgrp->pidlist_mutex);
|
|
|
|
list_for_each_entry(l, &cgrp->pidlists, links)
|
|
if (l->key.type == type && l->key.ns == ns)
|
|
return l;
|
|
return NULL;
|
|
}
|
|
|
|
/*
|
|
* find the appropriate pidlist for our purpose (given procs vs tasks)
|
|
* returns with the lock on that pidlist already held, and takes care
|
|
* of the use count, or returns NULL with no locks held if we're out of
|
|
* memory.
|
|
*/
|
|
static struct cgroup_pidlist *cgroup_pidlist_find_create(struct cgroup *cgrp,
|
|
enum cgroup_filetype type)
|
|
{
|
|
struct cgroup_pidlist *l;
|
|
|
|
lockdep_assert_held(&cgrp->pidlist_mutex);
|
|
|
|
l = cgroup_pidlist_find(cgrp, type);
|
|
if (l)
|
|
return l;
|
|
|
|
/* entry not found; create a new one */
|
|
l = kzalloc(sizeof(struct cgroup_pidlist), GFP_KERNEL);
|
|
if (!l)
|
|
return l;
|
|
|
|
INIT_DELAYED_WORK(&l->destroy_dwork, cgroup_pidlist_destroy_work_fn);
|
|
l->key.type = type;
|
|
/* don't need task_nsproxy() if we're looking at ourself */
|
|
l->key.ns = get_pid_ns(task_active_pid_ns(current));
|
|
l->owner = cgrp;
|
|
list_add(&l->links, &cgrp->pidlists);
|
|
return l;
|
|
}
|
|
|
|
/*
|
|
* Load a cgroup's pidarray with either procs' tgids or tasks' pids
|
|
*/
|
|
static int pidlist_array_load(struct cgroup *cgrp, enum cgroup_filetype type,
|
|
struct cgroup_pidlist **lp)
|
|
{
|
|
pid_t *array;
|
|
int length;
|
|
int pid, n = 0; /* used for populating the array */
|
|
struct css_task_iter it;
|
|
struct task_struct *tsk;
|
|
struct cgroup_pidlist *l;
|
|
|
|
lockdep_assert_held(&cgrp->pidlist_mutex);
|
|
|
|
/*
|
|
* If cgroup gets more users after we read count, we won't have
|
|
* enough space - tough. This race is indistinguishable to the
|
|
* caller from the case that the additional cgroup users didn't
|
|
* show up until sometime later on.
|
|
*/
|
|
length = cgroup_task_count(cgrp);
|
|
array = pidlist_allocate(length);
|
|
if (!array)
|
|
return -ENOMEM;
|
|
/* now, populate the array */
|
|
css_task_iter_start(&cgrp->dummy_css, &it);
|
|
while ((tsk = css_task_iter_next(&it))) {
|
|
if (unlikely(n == length))
|
|
break;
|
|
/* get tgid or pid for procs or tasks file respectively */
|
|
if (type == CGROUP_FILE_PROCS)
|
|
pid = task_tgid_vnr(tsk);
|
|
else
|
|
pid = task_pid_vnr(tsk);
|
|
if (pid > 0) /* make sure to only use valid results */
|
|
array[n++] = pid;
|
|
}
|
|
css_task_iter_end(&it);
|
|
length = n;
|
|
/* now sort & (if procs) strip out duplicates */
|
|
if (cgroup_sane_behavior(cgrp))
|
|
sort(array, length, sizeof(pid_t), fried_cmppid, NULL);
|
|
else
|
|
sort(array, length, sizeof(pid_t), cmppid, NULL);
|
|
if (type == CGROUP_FILE_PROCS)
|
|
length = pidlist_uniq(array, length);
|
|
|
|
l = cgroup_pidlist_find_create(cgrp, type);
|
|
if (!l) {
|
|
mutex_unlock(&cgrp->pidlist_mutex);
|
|
pidlist_free(array);
|
|
return -ENOMEM;
|
|
}
|
|
|
|
/* store array, freeing old if necessary */
|
|
pidlist_free(l->list);
|
|
l->list = array;
|
|
l->length = length;
|
|
*lp = l;
|
|
return 0;
|
|
}
|
|
|
|
/**
|
|
* cgroupstats_build - build and fill cgroupstats
|
|
* @stats: cgroupstats to fill information into
|
|
* @dentry: A dentry entry belonging to the cgroup for which stats have
|
|
* been requested.
|
|
*
|
|
* Build and fill cgroupstats so that taskstats can export it to user
|
|
* space.
|
|
*/
|
|
int cgroupstats_build(struct cgroupstats *stats, struct dentry *dentry)
|
|
{
|
|
struct kernfs_node *kn = kernfs_node_from_dentry(dentry);
|
|
struct cgroup *cgrp;
|
|
struct css_task_iter it;
|
|
struct task_struct *tsk;
|
|
|
|
/* it should be kernfs_node belonging to cgroupfs and is a directory */
|
|
if (dentry->d_sb->s_type != &cgroup_fs_type || !kn ||
|
|
kernfs_type(kn) != KERNFS_DIR)
|
|
return -EINVAL;
|
|
|
|
mutex_lock(&cgroup_mutex);
|
|
|
|
/*
|
|
* We aren't being called from kernfs and there's no guarantee on
|
|
* @kn->priv's validity. For this and css_tryget_from_dir(),
|
|
* @kn->priv is RCU safe. Let's do the RCU dancing.
|
|
*/
|
|
rcu_read_lock();
|
|
cgrp = rcu_dereference(kn->priv);
|
|
if (!cgrp || cgroup_is_dead(cgrp)) {
|
|
rcu_read_unlock();
|
|
mutex_unlock(&cgroup_mutex);
|
|
return -ENOENT;
|
|
}
|
|
rcu_read_unlock();
|
|
|
|
css_task_iter_start(&cgrp->dummy_css, &it);
|
|
while ((tsk = css_task_iter_next(&it))) {
|
|
switch (tsk->state) {
|
|
case TASK_RUNNING:
|
|
stats->nr_running++;
|
|
break;
|
|
case TASK_INTERRUPTIBLE:
|
|
stats->nr_sleeping++;
|
|
break;
|
|
case TASK_UNINTERRUPTIBLE:
|
|
stats->nr_uninterruptible++;
|
|
break;
|
|
case TASK_STOPPED:
|
|
stats->nr_stopped++;
|
|
break;
|
|
default:
|
|
if (delayacct_is_task_waiting_on_io(tsk))
|
|
stats->nr_io_wait++;
|
|
break;
|
|
}
|
|
}
|
|
css_task_iter_end(&it);
|
|
|
|
mutex_unlock(&cgroup_mutex);
|
|
return 0;
|
|
}
|
|
|
|
|
|
/*
|
|
* seq_file methods for the tasks/procs files. The seq_file position is the
|
|
* next pid to display; the seq_file iterator is a pointer to the pid
|
|
* in the cgroup->l->list array.
|
|
*/
|
|
|
|
static void *cgroup_pidlist_start(struct seq_file *s, loff_t *pos)
|
|
{
|
|
/*
|
|
* Initially we receive a position value that corresponds to
|
|
* one more than the last pid shown (or 0 on the first call or
|
|
* after a seek to the start). Use a binary-search to find the
|
|
* next pid to display, if any
|
|
*/
|
|
struct kernfs_open_file *of = s->private;
|
|
struct cgroup *cgrp = seq_css(s)->cgroup;
|
|
struct cgroup_pidlist *l;
|
|
enum cgroup_filetype type = seq_cft(s)->private;
|
|
int index = 0, pid = *pos;
|
|
int *iter, ret;
|
|
|
|
mutex_lock(&cgrp->pidlist_mutex);
|
|
|
|
/*
|
|
* !NULL @of->priv indicates that this isn't the first start()
|
|
* after open. If the matching pidlist is around, we can use that.
|
|
* Look for it. Note that @of->priv can't be used directly. It
|
|
* could already have been destroyed.
|
|
*/
|
|
if (of->priv)
|
|
of->priv = cgroup_pidlist_find(cgrp, type);
|
|
|
|
/*
|
|
* Either this is the first start() after open or the matching
|
|
* pidlist has been destroyed inbetween. Create a new one.
|
|
*/
|
|
if (!of->priv) {
|
|
ret = pidlist_array_load(cgrp, type,
|
|
(struct cgroup_pidlist **)&of->priv);
|
|
if (ret)
|
|
return ERR_PTR(ret);
|
|
}
|
|
l = of->priv;
|
|
|
|
if (pid) {
|
|
int end = l->length;
|
|
|
|
while (index < end) {
|
|
int mid = (index + end) / 2;
|
|
if (cgroup_pid_fry(cgrp, l->list[mid]) == pid) {
|
|
index = mid;
|
|
break;
|
|
} else if (cgroup_pid_fry(cgrp, l->list[mid]) <= pid)
|
|
index = mid + 1;
|
|
else
|
|
end = mid;
|
|
}
|
|
}
|
|
/* If we're off the end of the array, we're done */
|
|
if (index >= l->length)
|
|
return NULL;
|
|
/* Update the abstract position to be the actual pid that we found */
|
|
iter = l->list + index;
|
|
*pos = cgroup_pid_fry(cgrp, *iter);
|
|
return iter;
|
|
}
|
|
|
|
static void cgroup_pidlist_stop(struct seq_file *s, void *v)
|
|
{
|
|
struct kernfs_open_file *of = s->private;
|
|
struct cgroup_pidlist *l = of->priv;
|
|
|
|
if (l)
|
|
mod_delayed_work(cgroup_pidlist_destroy_wq, &l->destroy_dwork,
|
|
CGROUP_PIDLIST_DESTROY_DELAY);
|
|
mutex_unlock(&seq_css(s)->cgroup->pidlist_mutex);
|
|
}
|
|
|
|
static void *cgroup_pidlist_next(struct seq_file *s, void *v, loff_t *pos)
|
|
{
|
|
struct kernfs_open_file *of = s->private;
|
|
struct cgroup_pidlist *l = of->priv;
|
|
pid_t *p = v;
|
|
pid_t *end = l->list + l->length;
|
|
/*
|
|
* Advance to the next pid in the array. If this goes off the
|
|
* end, we're done
|
|
*/
|
|
p++;
|
|
if (p >= end) {
|
|
return NULL;
|
|
} else {
|
|
*pos = cgroup_pid_fry(seq_css(s)->cgroup, *p);
|
|
return p;
|
|
}
|
|
}
|
|
|
|
static int cgroup_pidlist_show(struct seq_file *s, void *v)
|
|
{
|
|
return seq_printf(s, "%d\n", *(int *)v);
|
|
}
|
|
|
|
/*
|
|
* seq_operations functions for iterating on pidlists through seq_file -
|
|
* independent of whether it's tasks or procs
|
|
*/
|
|
static const struct seq_operations cgroup_pidlist_seq_operations = {
|
|
.start = cgroup_pidlist_start,
|
|
.stop = cgroup_pidlist_stop,
|
|
.next = cgroup_pidlist_next,
|
|
.show = cgroup_pidlist_show,
|
|
};
|
|
|
|
static u64 cgroup_read_notify_on_release(struct cgroup_subsys_state *css,
|
|
struct cftype *cft)
|
|
{
|
|
return notify_on_release(css->cgroup);
|
|
}
|
|
|
|
static int cgroup_write_notify_on_release(struct cgroup_subsys_state *css,
|
|
struct cftype *cft, u64 val)
|
|
{
|
|
clear_bit(CGRP_RELEASABLE, &css->cgroup->flags);
|
|
if (val)
|
|
set_bit(CGRP_NOTIFY_ON_RELEASE, &css->cgroup->flags);
|
|
else
|
|
clear_bit(CGRP_NOTIFY_ON_RELEASE, &css->cgroup->flags);
|
|
return 0;
|
|
}
|
|
|
|
static u64 cgroup_clone_children_read(struct cgroup_subsys_state *css,
|
|
struct cftype *cft)
|
|
{
|
|
return test_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags);
|
|
}
|
|
|
|
static int cgroup_clone_children_write(struct cgroup_subsys_state *css,
|
|
struct cftype *cft, u64 val)
|
|
{
|
|
if (val)
|
|
set_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags);
|
|
else
|
|
clear_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags);
|
|
return 0;
|
|
}
|
|
|
|
static struct cftype cgroup_base_files[] = {
|
|
{
|
|
.name = "cgroup.procs",
|
|
.seq_start = cgroup_pidlist_start,
|
|
.seq_next = cgroup_pidlist_next,
|
|
.seq_stop = cgroup_pidlist_stop,
|
|
.seq_show = cgroup_pidlist_show,
|
|
.private = CGROUP_FILE_PROCS,
|
|
.write_u64 = cgroup_procs_write,
|
|
.mode = S_IRUGO | S_IWUSR,
|
|
},
|
|
{
|
|
.name = "cgroup.clone_children",
|
|
.flags = CFTYPE_INSANE,
|
|
.read_u64 = cgroup_clone_children_read,
|
|
.write_u64 = cgroup_clone_children_write,
|
|
},
|
|
{
|
|
.name = "cgroup.sane_behavior",
|
|
.flags = CFTYPE_ONLY_ON_ROOT,
|
|
.seq_show = cgroup_sane_behavior_show,
|
|
},
|
|
|
|
/*
|
|
* Historical crazy stuff. These don't have "cgroup." prefix and
|
|
* don't exist if sane_behavior. If you're depending on these, be
|
|
* prepared to be burned.
|
|
*/
|
|
{
|
|
.name = "tasks",
|
|
.flags = CFTYPE_INSANE, /* use "procs" instead */
|
|
.seq_start = cgroup_pidlist_start,
|
|
.seq_next = cgroup_pidlist_next,
|
|
.seq_stop = cgroup_pidlist_stop,
|
|
.seq_show = cgroup_pidlist_show,
|
|
.private = CGROUP_FILE_TASKS,
|
|
.write_u64 = cgroup_tasks_write,
|
|
.mode = S_IRUGO | S_IWUSR,
|
|
},
|
|
{
|
|
.name = "notify_on_release",
|
|
.flags = CFTYPE_INSANE,
|
|
.read_u64 = cgroup_read_notify_on_release,
|
|
.write_u64 = cgroup_write_notify_on_release,
|
|
},
|
|
{
|
|
.name = "release_agent",
|
|
.flags = CFTYPE_INSANE | CFTYPE_ONLY_ON_ROOT,
|
|
.seq_show = cgroup_release_agent_show,
|
|
.write_string = cgroup_release_agent_write,
|
|
.max_write_len = PATH_MAX - 1,
|
|
},
|
|
{ } /* terminate */
|
|
};
|
|
|
|
/**
|
|
* cgroup_populate_dir - create subsys files in a cgroup directory
|
|
* @cgrp: target cgroup
|
|
* @subsys_mask: mask of the subsystem ids whose files should be added
|
|
*
|
|
* On failure, no file is added.
|
|
*/
|
|
static int cgroup_populate_dir(struct cgroup *cgrp, unsigned long subsys_mask)
|
|
{
|
|
struct cgroup_subsys *ss;
|
|
int i, ret = 0;
|
|
|
|
/* process cftsets of each subsystem */
|
|
for_each_subsys(ss, i) {
|
|
struct cftype *cfts;
|
|
|
|
if (!test_bit(i, &subsys_mask))
|
|
continue;
|
|
|
|
list_for_each_entry(cfts, &ss->cfts, node) {
|
|
ret = cgroup_addrm_files(cgrp, cfts, true);
|
|
if (ret < 0)
|
|
goto err;
|
|
}
|
|
}
|
|
return 0;
|
|
err:
|
|
cgroup_clear_dir(cgrp, subsys_mask);
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* css destruction is four-stage process.
|
|
*
|
|
* 1. Destruction starts. Killing of the percpu_ref is initiated.
|
|
* Implemented in kill_css().
|
|
*
|
|
* 2. When the percpu_ref is confirmed to be visible as killed on all CPUs
|
|
* and thus css_tryget() is guaranteed to fail, the css can be offlined
|
|
* by invoking offline_css(). After offlining, the base ref is put.
|
|
* Implemented in css_killed_work_fn().
|
|
*
|
|
* 3. When the percpu_ref reaches zero, the only possible remaining
|
|
* accessors are inside RCU read sections. css_release() schedules the
|
|
* RCU callback.
|
|
*
|
|
* 4. After the grace period, the css can be freed. Implemented in
|
|
* css_free_work_fn().
|
|
*
|
|
* It is actually hairier because both step 2 and 4 require process context
|
|
* and thus involve punting to css->destroy_work adding two additional
|
|
* steps to the already complex sequence.
|
|
*/
|
|
static void css_free_work_fn(struct work_struct *work)
|
|
{
|
|
struct cgroup_subsys_state *css =
|
|
container_of(work, struct cgroup_subsys_state, destroy_work);
|
|
struct cgroup *cgrp = css->cgroup;
|
|
|
|
if (css->parent)
|
|
css_put(css->parent);
|
|
|
|
css->ss->css_free(css);
|
|
cgroup_put(cgrp);
|
|
}
|
|
|
|
static void css_free_rcu_fn(struct rcu_head *rcu_head)
|
|
{
|
|
struct cgroup_subsys_state *css =
|
|
container_of(rcu_head, struct cgroup_subsys_state, rcu_head);
|
|
|
|
INIT_WORK(&css->destroy_work, css_free_work_fn);
|
|
queue_work(cgroup_destroy_wq, &css->destroy_work);
|
|
}
|
|
|
|
static void css_release(struct percpu_ref *ref)
|
|
{
|
|
struct cgroup_subsys_state *css =
|
|
container_of(ref, struct cgroup_subsys_state, refcnt);
|
|
|
|
RCU_INIT_POINTER(css->cgroup->subsys[css->ss->id], NULL);
|
|
call_rcu(&css->rcu_head, css_free_rcu_fn);
|
|
}
|
|
|
|
static void init_css(struct cgroup_subsys_state *css, struct cgroup_subsys *ss,
|
|
struct cgroup *cgrp)
|
|
{
|
|
css->cgroup = cgrp;
|
|
css->ss = ss;
|
|
css->flags = 0;
|
|
|
|
if (cgrp->parent)
|
|
css->parent = cgroup_css(cgrp->parent, ss);
|
|
else
|
|
css->flags |= CSS_ROOT;
|
|
|
|
BUG_ON(cgroup_css(cgrp, ss));
|
|
}
|
|
|
|
/* invoke ->css_online() on a new CSS and mark it online if successful */
|
|
static int online_css(struct cgroup_subsys_state *css)
|
|
{
|
|
struct cgroup_subsys *ss = css->ss;
|
|
int ret = 0;
|
|
|
|
lockdep_assert_held(&cgroup_tree_mutex);
|
|
lockdep_assert_held(&cgroup_mutex);
|
|
|
|
if (ss->css_online)
|
|
ret = ss->css_online(css);
|
|
if (!ret) {
|
|
css->flags |= CSS_ONLINE;
|
|
css->cgroup->nr_css++;
|
|
rcu_assign_pointer(css->cgroup->subsys[ss->id], css);
|
|
}
|
|
return ret;
|
|
}
|
|
|
|
/* if the CSS is online, invoke ->css_offline() on it and mark it offline */
|
|
static void offline_css(struct cgroup_subsys_state *css)
|
|
{
|
|
struct cgroup_subsys *ss = css->ss;
|
|
|
|
lockdep_assert_held(&cgroup_tree_mutex);
|
|
lockdep_assert_held(&cgroup_mutex);
|
|
|
|
if (!(css->flags & CSS_ONLINE))
|
|
return;
|
|
|
|
if (ss->css_offline)
|
|
ss->css_offline(css);
|
|
|
|
css->flags &= ~CSS_ONLINE;
|
|
css->cgroup->nr_css--;
|
|
RCU_INIT_POINTER(css->cgroup->subsys[ss->id], css);
|
|
}
|
|
|
|
/**
|
|
* create_css - create a cgroup_subsys_state
|
|
* @cgrp: the cgroup new css will be associated with
|
|
* @ss: the subsys of new css
|
|
*
|
|
* Create a new css associated with @cgrp - @ss pair. On success, the new
|
|
* css is online and installed in @cgrp with all interface files created.
|
|
* Returns 0 on success, -errno on failure.
|
|
*/
|
|
static int create_css(struct cgroup *cgrp, struct cgroup_subsys *ss)
|
|
{
|
|
struct cgroup *parent = cgrp->parent;
|
|
struct cgroup_subsys_state *css;
|
|
int err;
|
|
|
|
lockdep_assert_held(&cgroup_mutex);
|
|
|
|
css = ss->css_alloc(cgroup_css(parent, ss));
|
|
if (IS_ERR(css))
|
|
return PTR_ERR(css);
|
|
|
|
err = percpu_ref_init(&css->refcnt, css_release);
|
|
if (err)
|
|
goto err_free_css;
|
|
|
|
init_css(css, ss, cgrp);
|
|
|
|
err = cgroup_populate_dir(cgrp, 1 << ss->id);
|
|
if (err)
|
|
goto err_free_percpu_ref;
|
|
|
|
err = online_css(css);
|
|
if (err)
|
|
goto err_clear_dir;
|
|
|
|
cgroup_get(cgrp);
|
|
css_get(css->parent);
|
|
|
|
cgrp->subsys_mask |= 1 << ss->id;
|
|
|
|
if (ss->broken_hierarchy && !ss->warned_broken_hierarchy &&
|
|
parent->parent) {
|
|
pr_warning("cgroup: %s (%d) created nested cgroup for controller \"%s\" which has incomplete hierarchy support. Nested cgroups may change behavior in the future.\n",
|
|
current->comm, current->pid, ss->name);
|
|
if (!strcmp(ss->name, "memory"))
|
|
pr_warning("cgroup: \"memory\" requires setting use_hierarchy to 1 on the root.\n");
|
|
ss->warned_broken_hierarchy = true;
|
|
}
|
|
|
|
return 0;
|
|
|
|
err_clear_dir:
|
|
cgroup_clear_dir(css->cgroup, 1 << css->ss->id);
|
|
err_free_percpu_ref:
|
|
percpu_ref_cancel_init(&css->refcnt);
|
|
err_free_css:
|
|
ss->css_free(css);
|
|
return err;
|
|
}
|
|
|
|
/**
|
|
* cgroup_create - create a cgroup
|
|
* @parent: cgroup that will be parent of the new cgroup
|
|
* @name: name of the new cgroup
|
|
* @mode: mode to set on new cgroup
|
|
*/
|
|
static long cgroup_create(struct cgroup *parent, const char *name,
|
|
umode_t mode)
|
|
{
|
|
struct cgroup *cgrp;
|
|
struct cgroup_root *root = parent->root;
|
|
int ssid, err;
|
|
struct cgroup_subsys *ss;
|
|
struct kernfs_node *kn;
|
|
|
|
/*
|
|
* XXX: The default hierarchy isn't fully implemented yet. Block
|
|
* !root cgroup creation on it for now.
|
|
*/
|
|
if (root == &cgrp_dfl_root)
|
|
return -EINVAL;
|
|
|
|
/* allocate the cgroup and its ID, 0 is reserved for the root */
|
|
cgrp = kzalloc(sizeof(*cgrp), GFP_KERNEL);
|
|
if (!cgrp)
|
|
return -ENOMEM;
|
|
|
|
mutex_lock(&cgroup_tree_mutex);
|
|
|
|
/*
|
|
* Only live parents can have children. Note that the liveliness
|
|
* check isn't strictly necessary because cgroup_mkdir() and
|
|
* cgroup_rmdir() are fully synchronized by i_mutex; however, do it
|
|
* anyway so that locking is contained inside cgroup proper and we
|
|
* don't get nasty surprises if we ever grow another caller.
|
|
*/
|
|
if (!cgroup_lock_live_group(parent)) {
|
|
err = -ENODEV;
|
|
goto err_unlock_tree;
|
|
}
|
|
|
|
/*
|
|
* Temporarily set the pointer to NULL, so idr_find() won't return
|
|
* a half-baked cgroup.
|
|
*/
|
|
cgrp->id = idr_alloc(&root->cgroup_idr, NULL, 1, 0, GFP_KERNEL);
|
|
if (cgrp->id < 0) {
|
|
err = -ENOMEM;
|
|
goto err_unlock;
|
|
}
|
|
|
|
init_cgroup_housekeeping(cgrp);
|
|
|
|
cgrp->parent = parent;
|
|
cgrp->dummy_css.parent = &parent->dummy_css;
|
|
cgrp->root = parent->root;
|
|
|
|
if (notify_on_release(parent))
|
|
set_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags);
|
|
|
|
if (test_bit(CGRP_CPUSET_CLONE_CHILDREN, &parent->flags))
|
|
set_bit(CGRP_CPUSET_CLONE_CHILDREN, &cgrp->flags);
|
|
|
|
/* create the directory */
|
|
kn = kernfs_create_dir(parent->kn, name, mode, cgrp);
|
|
if (IS_ERR(kn)) {
|
|
err = PTR_ERR(kn);
|
|
goto err_free_id;
|
|
}
|
|
cgrp->kn = kn;
|
|
|
|
/*
|
|
* This extra ref will be put in cgroup_free_fn() and guarantees
|
|
* that @cgrp->kn is always accessible.
|
|
*/
|
|
kernfs_get(kn);
|
|
|
|
cgrp->serial_nr = cgroup_serial_nr_next++;
|
|
|
|
/* allocation complete, commit to creation */
|
|
list_add_tail_rcu(&cgrp->sibling, &cgrp->parent->children);
|
|
atomic_inc(&root->nr_cgrps);
|
|
cgroup_get(parent);
|
|
|
|
/*
|
|
* @cgrp is now fully operational. If something fails after this
|
|
* point, it'll be released via the normal destruction path.
|
|
*/
|
|
idr_replace(&root->cgroup_idr, cgrp, cgrp->id);
|
|
|
|
err = cgroup_kn_set_ugid(kn);
|
|
if (err)
|
|
goto err_destroy;
|
|
|
|
err = cgroup_addrm_files(cgrp, cgroup_base_files, true);
|
|
if (err)
|
|
goto err_destroy;
|
|
|
|
/* let's create and online css's */
|
|
for_each_subsys(ss, ssid) {
|
|
if (root->cgrp.subsys_mask & (1 << ssid)) {
|
|
err = create_css(cgrp, ss);
|
|
if (err)
|
|
goto err_destroy;
|
|
}
|
|
}
|
|
|
|
kernfs_activate(kn);
|
|
|
|
mutex_unlock(&cgroup_mutex);
|
|
mutex_unlock(&cgroup_tree_mutex);
|
|
|
|
return 0;
|
|
|
|
err_free_id:
|
|
idr_remove(&root->cgroup_idr, cgrp->id);
|
|
err_unlock:
|
|
mutex_unlock(&cgroup_mutex);
|
|
err_unlock_tree:
|
|
mutex_unlock(&cgroup_tree_mutex);
|
|
kfree(cgrp);
|
|
return err;
|
|
|
|
err_destroy:
|
|
cgroup_destroy_locked(cgrp);
|
|
mutex_unlock(&cgroup_mutex);
|
|
mutex_unlock(&cgroup_tree_mutex);
|
|
return err;
|
|
}
|
|
|
|
static int cgroup_mkdir(struct kernfs_node *parent_kn, const char *name,
|
|
umode_t mode)
|
|
{
|
|
struct cgroup *parent = parent_kn->priv;
|
|
int ret;
|
|
|
|
/*
|
|
* cgroup_create() grabs cgroup_tree_mutex which nests outside
|
|
* kernfs active_ref and cgroup_create() already synchronizes
|
|
* properly against removal through cgroup_lock_live_group().
|
|
* Break it before calling cgroup_create().
|
|
*/
|
|
cgroup_get(parent);
|
|
kernfs_break_active_protection(parent_kn);
|
|
|
|
ret = cgroup_create(parent, name, mode);
|
|
|
|
kernfs_unbreak_active_protection(parent_kn);
|
|
cgroup_put(parent);
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* This is called when the refcnt of a css is confirmed to be killed.
|
|
* css_tryget() is now guaranteed to fail.
|
|
*/
|
|
static void css_killed_work_fn(struct work_struct *work)
|
|
{
|
|
struct cgroup_subsys_state *css =
|
|
container_of(work, struct cgroup_subsys_state, destroy_work);
|
|
struct cgroup *cgrp = css->cgroup;
|
|
|
|
mutex_lock(&cgroup_tree_mutex);
|
|
mutex_lock(&cgroup_mutex);
|
|
|
|
/*
|
|
* css_tryget() is guaranteed to fail now. Tell subsystems to
|
|
* initate destruction.
|
|
*/
|
|
offline_css(css);
|
|
|
|
/*
|
|
* If @cgrp is marked dead, it's waiting for refs of all css's to
|
|
* be disabled before proceeding to the second phase of cgroup
|
|
* destruction. If we are the last one, kick it off.
|
|
*/
|
|
if (!cgrp->nr_css && cgroup_is_dead(cgrp))
|
|
cgroup_destroy_css_killed(cgrp);
|
|
|
|
mutex_unlock(&cgroup_mutex);
|
|
mutex_unlock(&cgroup_tree_mutex);
|
|
|
|
/*
|
|
* Put the css refs from kill_css(). Each css holds an extra
|
|
* reference to the cgroup's dentry and cgroup removal proceeds
|
|
* regardless of css refs. On the last put of each css, whenever
|
|
* that may be, the extra dentry ref is put so that dentry
|
|
* destruction happens only after all css's are released.
|
|
*/
|
|
css_put(css);
|
|
}
|
|
|
|
/* css kill confirmation processing requires process context, bounce */
|
|
static void css_killed_ref_fn(struct percpu_ref *ref)
|
|
{
|
|
struct cgroup_subsys_state *css =
|
|
container_of(ref, struct cgroup_subsys_state, refcnt);
|
|
|
|
INIT_WORK(&css->destroy_work, css_killed_work_fn);
|
|
queue_work(cgroup_destroy_wq, &css->destroy_work);
|
|
}
|
|
|
|
static void __kill_css(struct cgroup_subsys_state *css)
|
|
{
|
|
lockdep_assert_held(&cgroup_tree_mutex);
|
|
|
|
/*
|
|
* This must happen before css is disassociated with its cgroup.
|
|
* See seq_css() for details.
|
|
*/
|
|
cgroup_clear_dir(css->cgroup, 1 << css->ss->id);
|
|
|
|
/*
|
|
* Killing would put the base ref, but we need to keep it alive
|
|
* until after ->css_offline().
|
|
*/
|
|
css_get(css);
|
|
|
|
/*
|
|
* cgroup core guarantees that, by the time ->css_offline() is
|
|
* invoked, no new css reference will be given out via
|
|
* css_tryget(). We can't simply call percpu_ref_kill() and
|
|
* proceed to offlining css's because percpu_ref_kill() doesn't
|
|
* guarantee that the ref is seen as killed on all CPUs on return.
|
|
*
|
|
* Use percpu_ref_kill_and_confirm() to get notifications as each
|
|
* css is confirmed to be seen as killed on all CPUs.
|
|
*/
|
|
percpu_ref_kill_and_confirm(&css->refcnt, css_killed_ref_fn);
|
|
}
|
|
|
|
/**
|
|
* kill_css - destroy a css
|
|
* @css: css to destroy
|
|
*
|
|
* This function initiates destruction of @css by removing cgroup interface
|
|
* files and putting its base reference. ->css_offline() will be invoked
|
|
* asynchronously once css_tryget() is guaranteed to fail and when the
|
|
* reference count reaches zero, @css will be released.
|
|
*/
|
|
static void kill_css(struct cgroup_subsys_state *css)
|
|
{
|
|
struct cgroup *cgrp = css->cgroup;
|
|
|
|
lockdep_assert_held(&cgroup_tree_mutex);
|
|
|
|
/* if already killed, noop */
|
|
if (cgrp->subsys_mask & (1 << css->ss->id)) {
|
|
cgrp->subsys_mask &= ~(1 << css->ss->id);
|
|
__kill_css(css);
|
|
}
|
|
}
|
|
|
|
/**
|
|
* cgroup_destroy_locked - the first stage of cgroup destruction
|
|
* @cgrp: cgroup to be destroyed
|
|
*
|
|
* css's make use of percpu refcnts whose killing latency shouldn't be
|
|
* exposed to userland and are RCU protected. Also, cgroup core needs to
|
|
* guarantee that css_tryget() won't succeed by the time ->css_offline() is
|
|
* invoked. To satisfy all the requirements, destruction is implemented in
|
|
* the following two steps.
|
|
*
|
|
* s1. Verify @cgrp can be destroyed and mark it dying. Remove all
|
|
* userland visible parts and start killing the percpu refcnts of
|
|
* css's. Set up so that the next stage will be kicked off once all
|
|
* the percpu refcnts are confirmed to be killed.
|
|
*
|
|
* s2. Invoke ->css_offline(), mark the cgroup dead and proceed with the
|
|
* rest of destruction. Once all cgroup references are gone, the
|
|
* cgroup is RCU-freed.
|
|
*
|
|
* This function implements s1. After this step, @cgrp is gone as far as
|
|
* the userland is concerned and a new cgroup with the same name may be
|
|
* created. As cgroup doesn't care about the names internally, this
|
|
* doesn't cause any problem.
|
|
*/
|
|
static int cgroup_destroy_locked(struct cgroup *cgrp)
|
|
__releases(&cgroup_mutex) __acquires(&cgroup_mutex)
|
|
{
|
|
struct cgroup *child;
|
|
struct cgroup_subsys_state *css;
|
|
bool empty;
|
|
int ssid;
|
|
|
|
lockdep_assert_held(&cgroup_tree_mutex);
|
|
lockdep_assert_held(&cgroup_mutex);
|
|
|
|
/*
|
|
* css_set_rwsem synchronizes access to ->cset_links and prevents
|
|
* @cgrp from being removed while put_css_set() is in progress.
|
|
*/
|
|
down_read(&css_set_rwsem);
|
|
empty = list_empty(&cgrp->cset_links);
|
|
up_read(&css_set_rwsem);
|
|
if (!empty)
|
|
return -EBUSY;
|
|
|
|
/*
|
|
* Make sure there's no live children. We can't test ->children
|
|
* emptiness as dead children linger on it while being destroyed;
|
|
* otherwise, "rmdir parent/child parent" may fail with -EBUSY.
|
|
*/
|
|
empty = true;
|
|
rcu_read_lock();
|
|
list_for_each_entry_rcu(child, &cgrp->children, sibling) {
|
|
empty = cgroup_is_dead(child);
|
|
if (!empty)
|
|
break;
|
|
}
|
|
rcu_read_unlock();
|
|
if (!empty)
|
|
return -EBUSY;
|
|
|
|
/*
|
|
* Mark @cgrp dead. This prevents further task migration and child
|
|
* creation by disabling cgroup_lock_live_group(). Note that
|
|
* CGRP_DEAD assertion is depended upon by css_next_child() to
|
|
* resume iteration after dropping RCU read lock. See
|
|
* css_next_child() for details.
|
|
*/
|
|
set_bit(CGRP_DEAD, &cgrp->flags);
|
|
|
|
/*
|
|
* Initiate massacre of all css's. cgroup_destroy_css_killed()
|
|
* will be invoked to perform the rest of destruction once the
|
|
* percpu refs of all css's are confirmed to be killed. This
|
|
* involves removing the subsystem's files, drop cgroup_mutex.
|
|
*/
|
|
mutex_unlock(&cgroup_mutex);
|
|
for_each_css(css, ssid, cgrp)
|
|
kill_css(css);
|
|
mutex_lock(&cgroup_mutex);
|
|
|
|
/* CGRP_DEAD is set, remove from ->release_list for the last time */
|
|
raw_spin_lock(&release_list_lock);
|
|
if (!list_empty(&cgrp->release_list))
|
|
list_del_init(&cgrp->release_list);
|
|
raw_spin_unlock(&release_list_lock);
|
|
|
|
/*
|
|
* If @cgrp has css's attached, the second stage of cgroup
|
|
* destruction is kicked off from css_killed_work_fn() after the
|
|
* refs of all attached css's are killed. If @cgrp doesn't have
|
|
* any css, we kick it off here.
|
|
*/
|
|
if (!cgrp->nr_css)
|
|
cgroup_destroy_css_killed(cgrp);
|
|
|
|
/* remove @cgrp directory along with the base files */
|
|
mutex_unlock(&cgroup_mutex);
|
|
|
|
/*
|
|
* There are two control paths which try to determine cgroup from
|
|
* dentry without going through kernfs - cgroupstats_build() and
|
|
* css_tryget_from_dir(). Those are supported by RCU protecting
|
|
* clearing of cgrp->kn->priv backpointer, which should happen
|
|
* after all files under it have been removed.
|
|
*/
|
|
kernfs_remove(cgrp->kn); /* @cgrp has an extra ref on its kn */
|
|
RCU_INIT_POINTER(*(void __rcu __force **)&cgrp->kn->priv, NULL);
|
|
|
|
mutex_lock(&cgroup_mutex);
|
|
|
|
return 0;
|
|
};
|
|
|
|
/**
|
|
* cgroup_destroy_css_killed - the second step of cgroup destruction
|
|
* @work: cgroup->destroy_free_work
|
|
*
|
|
* This function is invoked from a work item for a cgroup which is being
|
|
* destroyed after all css's are offlined and performs the rest of
|
|
* destruction. This is the second step of destruction described in the
|
|
* comment above cgroup_destroy_locked().
|
|
*/
|
|
static void cgroup_destroy_css_killed(struct cgroup *cgrp)
|
|
{
|
|
struct cgroup *parent = cgrp->parent;
|
|
|
|
lockdep_assert_held(&cgroup_tree_mutex);
|
|
lockdep_assert_held(&cgroup_mutex);
|
|
|
|
/* delete this cgroup from parent->children */
|
|
list_del_rcu(&cgrp->sibling);
|
|
|
|
cgroup_put(cgrp);
|
|
|
|
set_bit(CGRP_RELEASABLE, &parent->flags);
|
|
check_for_release(parent);
|
|
}
|
|
|
|
static int cgroup_rmdir(struct kernfs_node *kn)
|
|
{
|
|
struct cgroup *cgrp = kn->priv;
|
|
int ret = 0;
|
|
|
|
/*
|
|
* This is self-destruction but @kn can't be removed while this
|
|
* callback is in progress. Let's break active protection. Once
|
|
* the protection is broken, @cgrp can be destroyed at any point.
|
|
* Pin it so that it stays accessible.
|
|
*/
|
|
cgroup_get(cgrp);
|
|
kernfs_break_active_protection(kn);
|
|
|
|
mutex_lock(&cgroup_tree_mutex);
|
|
mutex_lock(&cgroup_mutex);
|
|
|
|
/*
|
|
* @cgrp might already have been destroyed while we're trying to
|
|
* grab the mutexes.
|
|
*/
|
|
if (!cgroup_is_dead(cgrp))
|
|
ret = cgroup_destroy_locked(cgrp);
|
|
|
|
mutex_unlock(&cgroup_mutex);
|
|
mutex_unlock(&cgroup_tree_mutex);
|
|
|
|
kernfs_unbreak_active_protection(kn);
|
|
cgroup_put(cgrp);
|
|
return ret;
|
|
}
|
|
|
|
static struct kernfs_syscall_ops cgroup_kf_syscall_ops = {
|
|
.remount_fs = cgroup_remount,
|
|
.show_options = cgroup_show_options,
|
|
.mkdir = cgroup_mkdir,
|
|
.rmdir = cgroup_rmdir,
|
|
.rename = cgroup_rename,
|
|
};
|
|
|
|
static void __init cgroup_init_subsys(struct cgroup_subsys *ss)
|
|
{
|
|
struct cgroup_subsys_state *css;
|
|
|
|
printk(KERN_INFO "Initializing cgroup subsys %s\n", ss->name);
|
|
|
|
mutex_lock(&cgroup_tree_mutex);
|
|
mutex_lock(&cgroup_mutex);
|
|
|
|
INIT_LIST_HEAD(&ss->cfts);
|
|
|
|
/* Create the root cgroup state for this subsystem */
|
|
ss->root = &cgrp_dfl_root;
|
|
css = ss->css_alloc(cgroup_css(&cgrp_dfl_root.cgrp, ss));
|
|
/* We don't handle early failures gracefully */
|
|
BUG_ON(IS_ERR(css));
|
|
init_css(css, ss, &cgrp_dfl_root.cgrp);
|
|
|
|
/* Update the init_css_set to contain a subsys
|
|
* pointer to this state - since the subsystem is
|
|
* newly registered, all tasks and hence the
|
|
* init_css_set is in the subsystem's root cgroup. */
|
|
init_css_set.subsys[ss->id] = css;
|
|
|
|
need_forkexit_callback |= ss->fork || ss->exit;
|
|
|
|
/* At system boot, before all subsystems have been
|
|
* registered, no tasks have been forked, so we don't
|
|
* need to invoke fork callbacks here. */
|
|
BUG_ON(!list_empty(&init_task.tasks));
|
|
|
|
BUG_ON(online_css(css));
|
|
|
|
cgrp_dfl_root.cgrp.subsys_mask |= 1 << ss->id;
|
|
|
|
mutex_unlock(&cgroup_mutex);
|
|
mutex_unlock(&cgroup_tree_mutex);
|
|
}
|
|
|
|
/**
|
|
* cgroup_init_early - cgroup initialization at system boot
|
|
*
|
|
* Initialize cgroups at system boot, and initialize any
|
|
* subsystems that request early init.
|
|
*/
|
|
int __init cgroup_init_early(void)
|
|
{
|
|
static struct cgroup_sb_opts __initdata opts =
|
|
{ .flags = CGRP_ROOT_SANE_BEHAVIOR };
|
|
struct cgroup_subsys *ss;
|
|
int i;
|
|
|
|
init_cgroup_root(&cgrp_dfl_root, &opts);
|
|
RCU_INIT_POINTER(init_task.cgroups, &init_css_set);
|
|
|
|
for_each_subsys(ss, i) {
|
|
WARN(!ss->css_alloc || !ss->css_free || ss->name || ss->id,
|
|
"invalid cgroup_subsys %d:%s css_alloc=%p css_free=%p name:id=%d:%s\n",
|
|
i, cgroup_subsys_name[i], ss->css_alloc, ss->css_free,
|
|
ss->id, ss->name);
|
|
WARN(strlen(cgroup_subsys_name[i]) > MAX_CGROUP_TYPE_NAMELEN,
|
|
"cgroup_subsys_name %s too long\n", cgroup_subsys_name[i]);
|
|
|
|
ss->id = i;
|
|
ss->name = cgroup_subsys_name[i];
|
|
|
|
if (ss->early_init)
|
|
cgroup_init_subsys(ss);
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
/**
|
|
* cgroup_init - cgroup initialization
|
|
*
|
|
* Register cgroup filesystem and /proc file, and initialize
|
|
* any subsystems that didn't request early init.
|
|
*/
|
|
int __init cgroup_init(void)
|
|
{
|
|
struct cgroup_subsys *ss;
|
|
unsigned long key;
|
|
int ssid, err;
|
|
|
|
BUG_ON(cgroup_init_cftypes(NULL, cgroup_base_files));
|
|
|
|
mutex_lock(&cgroup_tree_mutex);
|
|
mutex_lock(&cgroup_mutex);
|
|
|
|
/* Add init_css_set to the hash table */
|
|
key = css_set_hash(init_css_set.subsys);
|
|
hash_add(css_set_table, &init_css_set.hlist, key);
|
|
|
|
BUG_ON(cgroup_setup_root(&cgrp_dfl_root, 0));
|
|
|
|
mutex_unlock(&cgroup_mutex);
|
|
mutex_unlock(&cgroup_tree_mutex);
|
|
|
|
for_each_subsys(ss, ssid) {
|
|
if (!ss->early_init)
|
|
cgroup_init_subsys(ss);
|
|
|
|
/*
|
|
* cftype registration needs kmalloc and can't be done
|
|
* during early_init. Register base cftypes separately.
|
|
*/
|
|
if (ss->base_cftypes)
|
|
WARN_ON(cgroup_add_cftypes(ss, ss->base_cftypes));
|
|
}
|
|
|
|
cgroup_kobj = kobject_create_and_add("cgroup", fs_kobj);
|
|
if (!cgroup_kobj)
|
|
return -ENOMEM;
|
|
|
|
err = register_filesystem(&cgroup_fs_type);
|
|
if (err < 0) {
|
|
kobject_put(cgroup_kobj);
|
|
return err;
|
|
}
|
|
|
|
proc_create("cgroups", 0, NULL, &proc_cgroupstats_operations);
|
|
return 0;
|
|
}
|
|
|
|
static int __init cgroup_wq_init(void)
|
|
{
|
|
/*
|
|
* There isn't much point in executing destruction path in
|
|
* parallel. Good chunk is serialized with cgroup_mutex anyway.
|
|
* Use 1 for @max_active.
|
|
*
|
|
* We would prefer to do this in cgroup_init() above, but that
|
|
* is called before init_workqueues(): so leave this until after.
|
|
*/
|
|
cgroup_destroy_wq = alloc_workqueue("cgroup_destroy", 0, 1);
|
|
BUG_ON(!cgroup_destroy_wq);
|
|
|
|
/*
|
|
* Used to destroy pidlists and separate to serve as flush domain.
|
|
* Cap @max_active to 1 too.
|
|
*/
|
|
cgroup_pidlist_destroy_wq = alloc_workqueue("cgroup_pidlist_destroy",
|
|
0, 1);
|
|
BUG_ON(!cgroup_pidlist_destroy_wq);
|
|
|
|
return 0;
|
|
}
|
|
core_initcall(cgroup_wq_init);
|
|
|
|
/*
|
|
* proc_cgroup_show()
|
|
* - Print task's cgroup paths into seq_file, one line for each hierarchy
|
|
* - Used for /proc/<pid>/cgroup.
|
|
*/
|
|
|
|
/* TODO: Use a proper seq_file iterator */
|
|
int proc_cgroup_show(struct seq_file *m, void *v)
|
|
{
|
|
struct pid *pid;
|
|
struct task_struct *tsk;
|
|
char *buf, *path;
|
|
int retval;
|
|
struct cgroup_root *root;
|
|
|
|
retval = -ENOMEM;
|
|
buf = kmalloc(PATH_MAX, GFP_KERNEL);
|
|
if (!buf)
|
|
goto out;
|
|
|
|
retval = -ESRCH;
|
|
pid = m->private;
|
|
tsk = get_pid_task(pid, PIDTYPE_PID);
|
|
if (!tsk)
|
|
goto out_free;
|
|
|
|
retval = 0;
|
|
|
|
mutex_lock(&cgroup_mutex);
|
|
down_read(&css_set_rwsem);
|
|
|
|
for_each_root(root) {
|
|
struct cgroup_subsys *ss;
|
|
struct cgroup *cgrp;
|
|
int ssid, count = 0;
|
|
|
|
if (root == &cgrp_dfl_root && !cgrp_dfl_root_visible)
|
|
continue;
|
|
|
|
seq_printf(m, "%d:", root->hierarchy_id);
|
|
for_each_subsys(ss, ssid)
|
|
if (root->cgrp.subsys_mask & (1 << ssid))
|
|
seq_printf(m, "%s%s", count++ ? "," : "", ss->name);
|
|
if (strlen(root->name))
|
|
seq_printf(m, "%sname=%s", count ? "," : "",
|
|
root->name);
|
|
seq_putc(m, ':');
|
|
cgrp = task_cgroup_from_root(tsk, root);
|
|
path = cgroup_path(cgrp, buf, PATH_MAX);
|
|
if (!path) {
|
|
retval = -ENAMETOOLONG;
|
|
goto out_unlock;
|
|
}
|
|
seq_puts(m, path);
|
|
seq_putc(m, '\n');
|
|
}
|
|
|
|
out_unlock:
|
|
up_read(&css_set_rwsem);
|
|
mutex_unlock(&cgroup_mutex);
|
|
put_task_struct(tsk);
|
|
out_free:
|
|
kfree(buf);
|
|
out:
|
|
return retval;
|
|
}
|
|
|
|
/* Display information about each subsystem and each hierarchy */
|
|
static int proc_cgroupstats_show(struct seq_file *m, void *v)
|
|
{
|
|
struct cgroup_subsys *ss;
|
|
int i;
|
|
|
|
seq_puts(m, "#subsys_name\thierarchy\tnum_cgroups\tenabled\n");
|
|
/*
|
|
* ideally we don't want subsystems moving around while we do this.
|
|
* cgroup_mutex is also necessary to guarantee an atomic snapshot of
|
|
* subsys/hierarchy state.
|
|
*/
|
|
mutex_lock(&cgroup_mutex);
|
|
|
|
for_each_subsys(ss, i)
|
|
seq_printf(m, "%s\t%d\t%d\t%d\n",
|
|
ss->name, ss->root->hierarchy_id,
|
|
atomic_read(&ss->root->nr_cgrps), !ss->disabled);
|
|
|
|
mutex_unlock(&cgroup_mutex);
|
|
return 0;
|
|
}
|
|
|
|
static int cgroupstats_open(struct inode *inode, struct file *file)
|
|
{
|
|
return single_open(file, proc_cgroupstats_show, NULL);
|
|
}
|
|
|
|
static const struct file_operations proc_cgroupstats_operations = {
|
|
.open = cgroupstats_open,
|
|
.read = seq_read,
|
|
.llseek = seq_lseek,
|
|
.release = single_release,
|
|
};
|
|
|
|
/**
|
|
* cgroup_fork - initialize cgroup related fields during copy_process()
|
|
* @child: pointer to task_struct of forking parent process.
|
|
*
|
|
* A task is associated with the init_css_set until cgroup_post_fork()
|
|
* attaches it to the parent's css_set. Empty cg_list indicates that
|
|
* @child isn't holding reference to its css_set.
|
|
*/
|
|
void cgroup_fork(struct task_struct *child)
|
|
{
|
|
RCU_INIT_POINTER(child->cgroups, &init_css_set);
|
|
INIT_LIST_HEAD(&child->cg_list);
|
|
}
|
|
|
|
/**
|
|
* cgroup_post_fork - called on a new task after adding it to the task list
|
|
* @child: the task in question
|
|
*
|
|
* Adds the task to the list running through its css_set if necessary and
|
|
* call the subsystem fork() callbacks. Has to be after the task is
|
|
* visible on the task list in case we race with the first call to
|
|
* cgroup_task_iter_start() - to guarantee that the new task ends up on its
|
|
* list.
|
|
*/
|
|
void cgroup_post_fork(struct task_struct *child)
|
|
{
|
|
struct cgroup_subsys *ss;
|
|
int i;
|
|
|
|
/*
|
|
* This may race against cgroup_enable_task_cg_links(). As that
|
|
* function sets use_task_css_set_links before grabbing
|
|
* tasklist_lock and we just went through tasklist_lock to add
|
|
* @child, it's guaranteed that either we see the set
|
|
* use_task_css_set_links or cgroup_enable_task_cg_lists() sees
|
|
* @child during its iteration.
|
|
*
|
|
* If we won the race, @child is associated with %current's
|
|
* css_set. Grabbing css_set_rwsem guarantees both that the
|
|
* association is stable, and, on completion of the parent's
|
|
* migration, @child is visible in the source of migration or
|
|
* already in the destination cgroup. This guarantee is necessary
|
|
* when implementing operations which need to migrate all tasks of
|
|
* a cgroup to another.
|
|
*
|
|
* Note that if we lose to cgroup_enable_task_cg_links(), @child
|
|
* will remain in init_css_set. This is safe because all tasks are
|
|
* in the init_css_set before cg_links is enabled and there's no
|
|
* operation which transfers all tasks out of init_css_set.
|
|
*/
|
|
if (use_task_css_set_links) {
|
|
struct css_set *cset;
|
|
|
|
down_write(&css_set_rwsem);
|
|
cset = task_css_set(current);
|
|
if (list_empty(&child->cg_list)) {
|
|
rcu_assign_pointer(child->cgroups, cset);
|
|
list_add(&child->cg_list, &cset->tasks);
|
|
get_css_set(cset);
|
|
}
|
|
up_write(&css_set_rwsem);
|
|
}
|
|
|
|
/*
|
|
* Call ss->fork(). This must happen after @child is linked on
|
|
* css_set; otherwise, @child might change state between ->fork()
|
|
* and addition to css_set.
|
|
*/
|
|
if (need_forkexit_callback) {
|
|
for_each_subsys(ss, i)
|
|
if (ss->fork)
|
|
ss->fork(child);
|
|
}
|
|
}
|
|
|
|
/**
|
|
* cgroup_exit - detach cgroup from exiting task
|
|
* @tsk: pointer to task_struct of exiting process
|
|
*
|
|
* Description: Detach cgroup from @tsk and release it.
|
|
*
|
|
* Note that cgroups marked notify_on_release force every task in
|
|
* them to take the global cgroup_mutex mutex when exiting.
|
|
* This could impact scaling on very large systems. Be reluctant to
|
|
* use notify_on_release cgroups where very high task exit scaling
|
|
* is required on large systems.
|
|
*
|
|
* We set the exiting tasks cgroup to the root cgroup (top_cgroup). We
|
|
* call cgroup_exit() while the task is still competent to handle
|
|
* notify_on_release(), then leave the task attached to the root cgroup in
|
|
* each hierarchy for the remainder of its exit. No need to bother with
|
|
* init_css_set refcnting. init_css_set never goes away and we can't race
|
|
* with migration path - PF_EXITING is visible to migration path.
|
|
*/
|
|
void cgroup_exit(struct task_struct *tsk)
|
|
{
|
|
struct cgroup_subsys *ss;
|
|
struct css_set *cset;
|
|
bool put_cset = false;
|
|
int i;
|
|
|
|
/*
|
|
* Unlink from @tsk from its css_set. As migration path can't race
|
|
* with us, we can check cg_list without grabbing css_set_rwsem.
|
|
*/
|
|
if (!list_empty(&tsk->cg_list)) {
|
|
down_write(&css_set_rwsem);
|
|
list_del_init(&tsk->cg_list);
|
|
up_write(&css_set_rwsem);
|
|
put_cset = true;
|
|
}
|
|
|
|
/* Reassign the task to the init_css_set. */
|
|
cset = task_css_set(tsk);
|
|
RCU_INIT_POINTER(tsk->cgroups, &init_css_set);
|
|
|
|
if (need_forkexit_callback) {
|
|
/* see cgroup_post_fork() for details */
|
|
for_each_subsys(ss, i) {
|
|
if (ss->exit) {
|
|
struct cgroup_subsys_state *old_css = cset->subsys[i];
|
|
struct cgroup_subsys_state *css = task_css(tsk, i);
|
|
|
|
ss->exit(css, old_css, tsk);
|
|
}
|
|
}
|
|
}
|
|
|
|
if (put_cset)
|
|
put_css_set(cset, true);
|
|
}
|
|
|
|
static void check_for_release(struct cgroup *cgrp)
|
|
{
|
|
if (cgroup_is_releasable(cgrp) &&
|
|
list_empty(&cgrp->cset_links) && list_empty(&cgrp->children)) {
|
|
/*
|
|
* Control Group is currently removeable. If it's not
|
|
* already queued for a userspace notification, queue
|
|
* it now
|
|
*/
|
|
int need_schedule_work = 0;
|
|
|
|
raw_spin_lock(&release_list_lock);
|
|
if (!cgroup_is_dead(cgrp) &&
|
|
list_empty(&cgrp->release_list)) {
|
|
list_add(&cgrp->release_list, &release_list);
|
|
need_schedule_work = 1;
|
|
}
|
|
raw_spin_unlock(&release_list_lock);
|
|
if (need_schedule_work)
|
|
schedule_work(&release_agent_work);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Notify userspace when a cgroup is released, by running the
|
|
* configured release agent with the name of the cgroup (path
|
|
* relative to the root of cgroup file system) as the argument.
|
|
*
|
|
* Most likely, this user command will try to rmdir this cgroup.
|
|
*
|
|
* This races with the possibility that some other task will be
|
|
* attached to this cgroup before it is removed, or that some other
|
|
* user task will 'mkdir' a child cgroup of this cgroup. That's ok.
|
|
* The presumed 'rmdir' will fail quietly if this cgroup is no longer
|
|
* unused, and this cgroup will be reprieved from its death sentence,
|
|
* to continue to serve a useful existence. Next time it's released,
|
|
* we will get notified again, if it still has 'notify_on_release' set.
|
|
*
|
|
* The final arg to call_usermodehelper() is UMH_WAIT_EXEC, which
|
|
* means only wait until the task is successfully execve()'d. The
|
|
* separate release agent task is forked by call_usermodehelper(),
|
|
* then control in this thread returns here, without waiting for the
|
|
* release agent task. We don't bother to wait because the caller of
|
|
* this routine has no use for the exit status of the release agent
|
|
* task, so no sense holding our caller up for that.
|
|
*/
|
|
static void cgroup_release_agent(struct work_struct *work)
|
|
{
|
|
BUG_ON(work != &release_agent_work);
|
|
mutex_lock(&cgroup_mutex);
|
|
raw_spin_lock(&release_list_lock);
|
|
while (!list_empty(&release_list)) {
|
|
char *argv[3], *envp[3];
|
|
int i;
|
|
char *pathbuf = NULL, *agentbuf = NULL, *path;
|
|
struct cgroup *cgrp = list_entry(release_list.next,
|
|
struct cgroup,
|
|
release_list);
|
|
list_del_init(&cgrp->release_list);
|
|
raw_spin_unlock(&release_list_lock);
|
|
pathbuf = kmalloc(PATH_MAX, GFP_KERNEL);
|
|
if (!pathbuf)
|
|
goto continue_free;
|
|
path = cgroup_path(cgrp, pathbuf, PATH_MAX);
|
|
if (!path)
|
|
goto continue_free;
|
|
agentbuf = kstrdup(cgrp->root->release_agent_path, GFP_KERNEL);
|
|
if (!agentbuf)
|
|
goto continue_free;
|
|
|
|
i = 0;
|
|
argv[i++] = agentbuf;
|
|
argv[i++] = path;
|
|
argv[i] = NULL;
|
|
|
|
i = 0;
|
|
/* minimal command environment */
|
|
envp[i++] = "HOME=/";
|
|
envp[i++] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin";
|
|
envp[i] = NULL;
|
|
|
|
/* Drop the lock while we invoke the usermode helper,
|
|
* since the exec could involve hitting disk and hence
|
|
* be a slow process */
|
|
mutex_unlock(&cgroup_mutex);
|
|
call_usermodehelper(argv[0], argv, envp, UMH_WAIT_EXEC);
|
|
mutex_lock(&cgroup_mutex);
|
|
continue_free:
|
|
kfree(pathbuf);
|
|
kfree(agentbuf);
|
|
raw_spin_lock(&release_list_lock);
|
|
}
|
|
raw_spin_unlock(&release_list_lock);
|
|
mutex_unlock(&cgroup_mutex);
|
|
}
|
|
|
|
static int __init cgroup_disable(char *str)
|
|
{
|
|
struct cgroup_subsys *ss;
|
|
char *token;
|
|
int i;
|
|
|
|
while ((token = strsep(&str, ",")) != NULL) {
|
|
if (!*token)
|
|
continue;
|
|
|
|
for_each_subsys(ss, i) {
|
|
if (!strcmp(token, ss->name)) {
|
|
ss->disabled = 1;
|
|
printk(KERN_INFO "Disabling %s control group"
|
|
" subsystem\n", ss->name);
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
return 1;
|
|
}
|
|
__setup("cgroup_disable=", cgroup_disable);
|
|
|
|
/**
|
|
* css_tryget_from_dir - get corresponding css from the dentry of a cgroup dir
|
|
* @dentry: directory dentry of interest
|
|
* @ss: subsystem of interest
|
|
*
|
|
* If @dentry is a directory for a cgroup which has @ss enabled on it, try
|
|
* to get the corresponding css and return it. If such css doesn't exist
|
|
* or can't be pinned, an ERR_PTR value is returned.
|
|
*/
|
|
struct cgroup_subsys_state *css_tryget_from_dir(struct dentry *dentry,
|
|
struct cgroup_subsys *ss)
|
|
{
|
|
struct kernfs_node *kn = kernfs_node_from_dentry(dentry);
|
|
struct cgroup_subsys_state *css = NULL;
|
|
struct cgroup *cgrp;
|
|
|
|
/* is @dentry a cgroup dir? */
|
|
if (dentry->d_sb->s_type != &cgroup_fs_type || !kn ||
|
|
kernfs_type(kn) != KERNFS_DIR)
|
|
return ERR_PTR(-EBADF);
|
|
|
|
rcu_read_lock();
|
|
|
|
/*
|
|
* This path doesn't originate from kernfs and @kn could already
|
|
* have been or be removed at any point. @kn->priv is RCU
|
|
* protected for this access. See destroy_locked() for details.
|
|
*/
|
|
cgrp = rcu_dereference(kn->priv);
|
|
if (cgrp)
|
|
css = cgroup_css(cgrp, ss);
|
|
|
|
if (!css || !css_tryget(css))
|
|
css = ERR_PTR(-ENOENT);
|
|
|
|
rcu_read_unlock();
|
|
return css;
|
|
}
|
|
|
|
/**
|
|
* css_from_id - lookup css by id
|
|
* @id: the cgroup id
|
|
* @ss: cgroup subsys to be looked into
|
|
*
|
|
* Returns the css if there's valid one with @id, otherwise returns NULL.
|
|
* Should be called under rcu_read_lock().
|
|
*/
|
|
struct cgroup_subsys_state *css_from_id(int id, struct cgroup_subsys *ss)
|
|
{
|
|
struct cgroup *cgrp;
|
|
|
|
cgroup_assert_mutexes_or_rcu_locked();
|
|
|
|
cgrp = idr_find(&ss->root->cgroup_idr, id);
|
|
if (cgrp)
|
|
return cgroup_css(cgrp, ss);
|
|
return NULL;
|
|
}
|
|
|
|
#ifdef CONFIG_CGROUP_DEBUG
|
|
static struct cgroup_subsys_state *
|
|
debug_css_alloc(struct cgroup_subsys_state *parent_css)
|
|
{
|
|
struct cgroup_subsys_state *css = kzalloc(sizeof(*css), GFP_KERNEL);
|
|
|
|
if (!css)
|
|
return ERR_PTR(-ENOMEM);
|
|
|
|
return css;
|
|
}
|
|
|
|
static void debug_css_free(struct cgroup_subsys_state *css)
|
|
{
|
|
kfree(css);
|
|
}
|
|
|
|
static u64 debug_taskcount_read(struct cgroup_subsys_state *css,
|
|
struct cftype *cft)
|
|
{
|
|
return cgroup_task_count(css->cgroup);
|
|
}
|
|
|
|
static u64 current_css_set_read(struct cgroup_subsys_state *css,
|
|
struct cftype *cft)
|
|
{
|
|
return (u64)(unsigned long)current->cgroups;
|
|
}
|
|
|
|
static u64 current_css_set_refcount_read(struct cgroup_subsys_state *css,
|
|
struct cftype *cft)
|
|
{
|
|
u64 count;
|
|
|
|
rcu_read_lock();
|
|
count = atomic_read(&task_css_set(current)->refcount);
|
|
rcu_read_unlock();
|
|
return count;
|
|
}
|
|
|
|
static int current_css_set_cg_links_read(struct seq_file *seq, void *v)
|
|
{
|
|
struct cgrp_cset_link *link;
|
|
struct css_set *cset;
|
|
char *name_buf;
|
|
|
|
name_buf = kmalloc(NAME_MAX + 1, GFP_KERNEL);
|
|
if (!name_buf)
|
|
return -ENOMEM;
|
|
|
|
down_read(&css_set_rwsem);
|
|
rcu_read_lock();
|
|
cset = rcu_dereference(current->cgroups);
|
|
list_for_each_entry(link, &cset->cgrp_links, cgrp_link) {
|
|
struct cgroup *c = link->cgrp;
|
|
|
|
cgroup_name(c, name_buf, NAME_MAX + 1);
|
|
seq_printf(seq, "Root %d group %s\n",
|
|
c->root->hierarchy_id, name_buf);
|
|
}
|
|
rcu_read_unlock();
|
|
up_read(&css_set_rwsem);
|
|
kfree(name_buf);
|
|
return 0;
|
|
}
|
|
|
|
#define MAX_TASKS_SHOWN_PER_CSS 25
|
|
static int cgroup_css_links_read(struct seq_file *seq, void *v)
|
|
{
|
|
struct cgroup_subsys_state *css = seq_css(seq);
|
|
struct cgrp_cset_link *link;
|
|
|
|
down_read(&css_set_rwsem);
|
|
list_for_each_entry(link, &css->cgroup->cset_links, cset_link) {
|
|
struct css_set *cset = link->cset;
|
|
struct task_struct *task;
|
|
int count = 0;
|
|
|
|
seq_printf(seq, "css_set %p\n", cset);
|
|
|
|
list_for_each_entry(task, &cset->tasks, cg_list) {
|
|
if (count++ > MAX_TASKS_SHOWN_PER_CSS)
|
|
goto overflow;
|
|
seq_printf(seq, " task %d\n", task_pid_vnr(task));
|
|
}
|
|
|
|
list_for_each_entry(task, &cset->mg_tasks, cg_list) {
|
|
if (count++ > MAX_TASKS_SHOWN_PER_CSS)
|
|
goto overflow;
|
|
seq_printf(seq, " task %d\n", task_pid_vnr(task));
|
|
}
|
|
continue;
|
|
overflow:
|
|
seq_puts(seq, " ...\n");
|
|
}
|
|
up_read(&css_set_rwsem);
|
|
return 0;
|
|
}
|
|
|
|
static u64 releasable_read(struct cgroup_subsys_state *css, struct cftype *cft)
|
|
{
|
|
return test_bit(CGRP_RELEASABLE, &css->cgroup->flags);
|
|
}
|
|
|
|
static struct cftype debug_files[] = {
|
|
{
|
|
.name = "taskcount",
|
|
.read_u64 = debug_taskcount_read,
|
|
},
|
|
|
|
{
|
|
.name = "current_css_set",
|
|
.read_u64 = current_css_set_read,
|
|
},
|
|
|
|
{
|
|
.name = "current_css_set_refcount",
|
|
.read_u64 = current_css_set_refcount_read,
|
|
},
|
|
|
|
{
|
|
.name = "current_css_set_cg_links",
|
|
.seq_show = current_css_set_cg_links_read,
|
|
},
|
|
|
|
{
|
|
.name = "cgroup_css_links",
|
|
.seq_show = cgroup_css_links_read,
|
|
},
|
|
|
|
{
|
|
.name = "releasable",
|
|
.read_u64 = releasable_read,
|
|
},
|
|
|
|
{ } /* terminate */
|
|
};
|
|
|
|
struct cgroup_subsys debug_cgrp_subsys = {
|
|
.css_alloc = debug_css_alloc,
|
|
.css_free = debug_css_free,
|
|
.base_cftypes = debug_files,
|
|
};
|
|
#endif /* CONFIG_CGROUP_DEBUG */
|