424 lines
11 KiB
C
424 lines
11 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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#include "cgroup-internal.h"
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#include <linux/sched/cputime.h>
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static DEFINE_SPINLOCK(cgroup_rstat_lock);
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static DEFINE_PER_CPU(raw_spinlock_t, cgroup_rstat_cpu_lock);
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static void cgroup_base_stat_flush(struct cgroup *cgrp, int cpu);
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static struct cgroup_rstat_cpu *cgroup_rstat_cpu(struct cgroup *cgrp, int cpu)
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{
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return per_cpu_ptr(cgrp->rstat_cpu, cpu);
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}
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/**
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* cgroup_rstat_updated - keep track of updated rstat_cpu
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* @cgrp: target cgroup
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* @cpu: cpu on which rstat_cpu was updated
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*
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* @cgrp's rstat_cpu on @cpu was updated. Put it on the parent's matching
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* rstat_cpu->updated_children list. See the comment on top of
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* cgroup_rstat_cpu definition for details.
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*/
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void cgroup_rstat_updated(struct cgroup *cgrp, int cpu)
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{
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raw_spinlock_t *cpu_lock = per_cpu_ptr(&cgroup_rstat_cpu_lock, cpu);
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struct cgroup *parent;
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unsigned long flags;
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/* nothing to do for root */
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if (!cgroup_parent(cgrp))
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return;
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/*
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* Paired with the one in cgroup_rstat_cpu_pop_updated(). Either we
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* see NULL updated_next or they see our updated stat.
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*/
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smp_mb();
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/*
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* Because @parent's updated_children is terminated with @parent
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* instead of NULL, we can tell whether @cgrp is on the list by
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* testing the next pointer for NULL.
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*/
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if (cgroup_rstat_cpu(cgrp, cpu)->updated_next)
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return;
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raw_spin_lock_irqsave(cpu_lock, flags);
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/* put @cgrp and all ancestors on the corresponding updated lists */
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for (parent = cgroup_parent(cgrp); parent;
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cgrp = parent, parent = cgroup_parent(cgrp)) {
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struct cgroup_rstat_cpu *rstatc = cgroup_rstat_cpu(cgrp, cpu);
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struct cgroup_rstat_cpu *prstatc = cgroup_rstat_cpu(parent, cpu);
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/*
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* Both additions and removals are bottom-up. If a cgroup
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* is already in the tree, all ancestors are.
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*/
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if (rstatc->updated_next)
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break;
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rstatc->updated_next = prstatc->updated_children;
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prstatc->updated_children = cgrp;
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}
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raw_spin_unlock_irqrestore(cpu_lock, flags);
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}
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EXPORT_SYMBOL_GPL(cgroup_rstat_updated);
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/**
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* cgroup_rstat_cpu_pop_updated - iterate and dismantle rstat_cpu updated tree
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* @pos: current position
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* @root: root of the tree to traversal
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* @cpu: target cpu
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*
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* Walks the udpated rstat_cpu tree on @cpu from @root. %NULL @pos starts
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* the traversal and %NULL return indicates the end. During traversal,
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* each returned cgroup is unlinked from the tree. Must be called with the
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* matching cgroup_rstat_cpu_lock held.
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*
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* The only ordering guarantee is that, for a parent and a child pair
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* covered by a given traversal, if a child is visited, its parent is
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* guaranteed to be visited afterwards.
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*/
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static struct cgroup *cgroup_rstat_cpu_pop_updated(struct cgroup *pos,
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struct cgroup *root, int cpu)
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{
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struct cgroup_rstat_cpu *rstatc;
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if (pos == root)
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return NULL;
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/*
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* We're gonna walk down to the first leaf and visit/remove it. We
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* can pick whatever unvisited node as the starting point.
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*/
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if (!pos)
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pos = root;
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else
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pos = cgroup_parent(pos);
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/* walk down to the first leaf */
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while (true) {
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rstatc = cgroup_rstat_cpu(pos, cpu);
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if (rstatc->updated_children == pos)
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break;
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pos = rstatc->updated_children;
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}
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/*
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* Unlink @pos from the tree. As the updated_children list is
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* singly linked, we have to walk it to find the removal point.
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* However, due to the way we traverse, @pos will be the first
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* child in most cases. The only exception is @root.
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*/
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if (rstatc->updated_next) {
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struct cgroup *parent = cgroup_parent(pos);
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struct cgroup_rstat_cpu *prstatc = cgroup_rstat_cpu(parent, cpu);
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struct cgroup_rstat_cpu *nrstatc;
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struct cgroup **nextp;
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nextp = &prstatc->updated_children;
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while (true) {
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nrstatc = cgroup_rstat_cpu(*nextp, cpu);
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if (*nextp == pos)
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break;
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WARN_ON_ONCE(*nextp == parent);
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nextp = &nrstatc->updated_next;
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}
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*nextp = rstatc->updated_next;
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rstatc->updated_next = NULL;
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/*
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* Paired with the one in cgroup_rstat_cpu_updated().
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* Either they see NULL updated_next or we see their
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* updated stat.
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*/
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smp_mb();
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return pos;
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}
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/* only happens for @root */
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return NULL;
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}
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/* see cgroup_rstat_flush() */
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static void cgroup_rstat_flush_locked(struct cgroup *cgrp, bool may_sleep)
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__releases(&cgroup_rstat_lock) __acquires(&cgroup_rstat_lock)
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{
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int cpu;
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lockdep_assert_held(&cgroup_rstat_lock);
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for_each_possible_cpu(cpu) {
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raw_spinlock_t *cpu_lock = per_cpu_ptr(&cgroup_rstat_cpu_lock,
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cpu);
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struct cgroup *pos = NULL;
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raw_spin_lock(cpu_lock);
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while ((pos = cgroup_rstat_cpu_pop_updated(pos, cgrp, cpu))) {
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struct cgroup_subsys_state *css;
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cgroup_base_stat_flush(pos, cpu);
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rcu_read_lock();
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list_for_each_entry_rcu(css, &pos->rstat_css_list,
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rstat_css_node)
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css->ss->css_rstat_flush(css, cpu);
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rcu_read_unlock();
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}
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raw_spin_unlock(cpu_lock);
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/* if @may_sleep, play nice and yield if necessary */
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if (may_sleep && (need_resched() ||
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spin_needbreak(&cgroup_rstat_lock))) {
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spin_unlock_irq(&cgroup_rstat_lock);
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if (!cond_resched())
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cpu_relax();
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spin_lock_irq(&cgroup_rstat_lock);
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}
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}
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}
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/**
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* cgroup_rstat_flush - flush stats in @cgrp's subtree
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* @cgrp: target cgroup
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*
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* Collect all per-cpu stats in @cgrp's subtree into the global counters
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* and propagate them upwards. After this function returns, all cgroups in
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* the subtree have up-to-date ->stat.
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*
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* This also gets all cgroups in the subtree including @cgrp off the
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* ->updated_children lists.
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*
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* This function may block.
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*/
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void cgroup_rstat_flush(struct cgroup *cgrp)
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{
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might_sleep();
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spin_lock_irq(&cgroup_rstat_lock);
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cgroup_rstat_flush_locked(cgrp, true);
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spin_unlock_irq(&cgroup_rstat_lock);
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}
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/**
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* cgroup_rstat_flush_irqsafe - irqsafe version of cgroup_rstat_flush()
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* @cgrp: target cgroup
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*
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* This function can be called from any context.
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*/
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void cgroup_rstat_flush_irqsafe(struct cgroup *cgrp)
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{
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unsigned long flags;
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spin_lock_irqsave(&cgroup_rstat_lock, flags);
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cgroup_rstat_flush_locked(cgrp, false);
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spin_unlock_irqrestore(&cgroup_rstat_lock, flags);
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}
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/**
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* cgroup_rstat_flush_begin - flush stats in @cgrp's subtree and hold
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* @cgrp: target cgroup
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*
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* Flush stats in @cgrp's subtree and prevent further flushes. Must be
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* paired with cgroup_rstat_flush_release().
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*
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* This function may block.
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*/
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void cgroup_rstat_flush_hold(struct cgroup *cgrp)
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__acquires(&cgroup_rstat_lock)
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{
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might_sleep();
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spin_lock_irq(&cgroup_rstat_lock);
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cgroup_rstat_flush_locked(cgrp, true);
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}
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/**
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* cgroup_rstat_flush_release - release cgroup_rstat_flush_hold()
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*/
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void cgroup_rstat_flush_release(void)
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__releases(&cgroup_rstat_lock)
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{
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spin_unlock_irq(&cgroup_rstat_lock);
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}
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int cgroup_rstat_init(struct cgroup *cgrp)
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{
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int cpu;
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/* the root cgrp has rstat_cpu preallocated */
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if (!cgrp->rstat_cpu) {
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cgrp->rstat_cpu = alloc_percpu(struct cgroup_rstat_cpu);
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if (!cgrp->rstat_cpu)
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return -ENOMEM;
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}
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/* ->updated_children list is self terminated */
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for_each_possible_cpu(cpu) {
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struct cgroup_rstat_cpu *rstatc = cgroup_rstat_cpu(cgrp, cpu);
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rstatc->updated_children = cgrp;
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u64_stats_init(&rstatc->bsync);
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}
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return 0;
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}
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void cgroup_rstat_exit(struct cgroup *cgrp)
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{
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int cpu;
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cgroup_rstat_flush(cgrp);
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/* sanity check */
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for_each_possible_cpu(cpu) {
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struct cgroup_rstat_cpu *rstatc = cgroup_rstat_cpu(cgrp, cpu);
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if (WARN_ON_ONCE(rstatc->updated_children != cgrp) ||
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WARN_ON_ONCE(rstatc->updated_next))
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return;
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}
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free_percpu(cgrp->rstat_cpu);
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cgrp->rstat_cpu = NULL;
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}
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void __init cgroup_rstat_boot(void)
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{
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int cpu;
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for_each_possible_cpu(cpu)
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raw_spin_lock_init(per_cpu_ptr(&cgroup_rstat_cpu_lock, cpu));
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BUG_ON(cgroup_rstat_init(&cgrp_dfl_root.cgrp));
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}
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/*
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* Functions for cgroup basic resource statistics implemented on top of
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* rstat.
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*/
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static void cgroup_base_stat_add(struct cgroup_base_stat *dst_bstat,
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struct cgroup_base_stat *src_bstat)
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{
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dst_bstat->cputime.utime += src_bstat->cputime.utime;
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dst_bstat->cputime.stime += src_bstat->cputime.stime;
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dst_bstat->cputime.sum_exec_runtime += src_bstat->cputime.sum_exec_runtime;
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}
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static void cgroup_base_stat_sub(struct cgroup_base_stat *dst_bstat,
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struct cgroup_base_stat *src_bstat)
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{
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dst_bstat->cputime.utime -= src_bstat->cputime.utime;
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dst_bstat->cputime.stime -= src_bstat->cputime.stime;
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dst_bstat->cputime.sum_exec_runtime -= src_bstat->cputime.sum_exec_runtime;
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}
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static void cgroup_base_stat_flush(struct cgroup *cgrp, int cpu)
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{
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struct cgroup *parent = cgroup_parent(cgrp);
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struct cgroup_rstat_cpu *rstatc = cgroup_rstat_cpu(cgrp, cpu);
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struct cgroup_base_stat cur, delta;
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unsigned seq;
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/* fetch the current per-cpu values */
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do {
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seq = __u64_stats_fetch_begin(&rstatc->bsync);
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cur.cputime = rstatc->bstat.cputime;
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} while (__u64_stats_fetch_retry(&rstatc->bsync, seq));
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/* propagate percpu delta to global */
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delta = cur;
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cgroup_base_stat_sub(&delta, &rstatc->last_bstat);
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cgroup_base_stat_add(&cgrp->bstat, &delta);
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cgroup_base_stat_add(&rstatc->last_bstat, &delta);
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/* propagate global delta to parent */
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if (parent) {
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delta = cgrp->bstat;
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cgroup_base_stat_sub(&delta, &cgrp->last_bstat);
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cgroup_base_stat_add(&parent->bstat, &delta);
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cgroup_base_stat_add(&cgrp->last_bstat, &delta);
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}
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}
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static struct cgroup_rstat_cpu *
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cgroup_base_stat_cputime_account_begin(struct cgroup *cgrp)
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{
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struct cgroup_rstat_cpu *rstatc;
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rstatc = get_cpu_ptr(cgrp->rstat_cpu);
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u64_stats_update_begin(&rstatc->bsync);
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return rstatc;
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}
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static void cgroup_base_stat_cputime_account_end(struct cgroup *cgrp,
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struct cgroup_rstat_cpu *rstatc)
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{
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u64_stats_update_end(&rstatc->bsync);
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cgroup_rstat_updated(cgrp, smp_processor_id());
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put_cpu_ptr(rstatc);
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}
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void __cgroup_account_cputime(struct cgroup *cgrp, u64 delta_exec)
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{
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struct cgroup_rstat_cpu *rstatc;
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rstatc = cgroup_base_stat_cputime_account_begin(cgrp);
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rstatc->bstat.cputime.sum_exec_runtime += delta_exec;
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cgroup_base_stat_cputime_account_end(cgrp, rstatc);
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}
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void __cgroup_account_cputime_field(struct cgroup *cgrp,
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enum cpu_usage_stat index, u64 delta_exec)
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{
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struct cgroup_rstat_cpu *rstatc;
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rstatc = cgroup_base_stat_cputime_account_begin(cgrp);
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switch (index) {
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case CPUTIME_USER:
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case CPUTIME_NICE:
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rstatc->bstat.cputime.utime += delta_exec;
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break;
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case CPUTIME_SYSTEM:
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case CPUTIME_IRQ:
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case CPUTIME_SOFTIRQ:
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rstatc->bstat.cputime.stime += delta_exec;
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break;
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default:
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break;
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}
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cgroup_base_stat_cputime_account_end(cgrp, rstatc);
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}
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void cgroup_base_stat_cputime_show(struct seq_file *seq)
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{
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struct cgroup *cgrp = seq_css(seq)->cgroup;
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u64 usage, utime, stime;
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if (!cgroup_parent(cgrp))
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return;
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cgroup_rstat_flush_hold(cgrp);
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usage = cgrp->bstat.cputime.sum_exec_runtime;
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cputime_adjust(&cgrp->bstat.cputime, &cgrp->prev_cputime, &utime, &stime);
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cgroup_rstat_flush_release();
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do_div(usage, NSEC_PER_USEC);
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do_div(utime, NSEC_PER_USEC);
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do_div(stime, NSEC_PER_USEC);
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seq_printf(seq, "usage_usec %llu\n"
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"user_usec %llu\n"
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"system_usec %llu\n",
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usage, utime, stime);
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}
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