146 lines
5.2 KiB
C
146 lines
5.2 KiB
C
/*
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* Sleepable Read-Copy Update mechanism for mutual exclusion,
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* tree variant.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, you can access it online at
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* http://www.gnu.org/licenses/gpl-2.0.html.
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*
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* Copyright (C) IBM Corporation, 2017
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*
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* Author: Paul McKenney <paulmck@us.ibm.com>
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*/
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#ifndef _LINUX_SRCU_TREE_H
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#define _LINUX_SRCU_TREE_H
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#include <linux/rcu_node_tree.h>
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#include <linux/completion.h>
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struct srcu_node;
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struct srcu_struct;
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/*
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* Per-CPU structure feeding into leaf srcu_node, similar in function
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* to rcu_node.
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*/
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struct srcu_data {
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/* Read-side state. */
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unsigned long srcu_lock_count[2]; /* Locks per CPU. */
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unsigned long srcu_unlock_count[2]; /* Unlocks per CPU. */
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/* Update-side state. */
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spinlock_t __private lock ____cacheline_internodealigned_in_smp;
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struct rcu_segcblist srcu_cblist; /* List of callbacks.*/
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unsigned long srcu_gp_seq_needed; /* Furthest future GP needed. */
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unsigned long srcu_gp_seq_needed_exp; /* Furthest future exp GP. */
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bool srcu_cblist_invoking; /* Invoking these CBs? */
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struct delayed_work work; /* Context for CB invoking. */
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struct rcu_head srcu_barrier_head; /* For srcu_barrier() use. */
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struct srcu_node *mynode; /* Leaf srcu_node. */
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unsigned long grpmask; /* Mask for leaf srcu_node */
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/* ->srcu_data_have_cbs[]. */
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int cpu;
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struct srcu_struct *sp;
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};
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/*
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* Node in SRCU combining tree, similar in function to rcu_data.
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*/
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struct srcu_node {
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spinlock_t __private lock;
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unsigned long srcu_have_cbs[4]; /* GP seq for children */
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/* having CBs, but only */
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/* is > ->srcu_gq_seq. */
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unsigned long srcu_data_have_cbs[4]; /* Which srcu_data structs */
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/* have CBs for given GP? */
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unsigned long srcu_gp_seq_needed_exp; /* Furthest future exp GP. */
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struct srcu_node *srcu_parent; /* Next up in tree. */
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int grplo; /* Least CPU for node. */
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int grphi; /* Biggest CPU for node. */
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};
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/*
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* Per-SRCU-domain structure, similar in function to rcu_state.
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*/
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struct srcu_struct {
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struct srcu_node node[NUM_RCU_NODES]; /* Combining tree. */
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struct srcu_node *level[RCU_NUM_LVLS + 1];
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/* First node at each level. */
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struct mutex srcu_cb_mutex; /* Serialize CB preparation. */
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spinlock_t __private lock; /* Protect counters */
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struct mutex srcu_gp_mutex; /* Serialize GP work. */
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unsigned int srcu_idx; /* Current rdr array element. */
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unsigned long srcu_gp_seq; /* Grace-period seq #. */
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unsigned long srcu_gp_seq_needed; /* Latest gp_seq needed. */
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unsigned long srcu_gp_seq_needed_exp; /* Furthest future exp GP. */
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unsigned long srcu_last_gp_end; /* Last GP end timestamp (ns) */
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struct srcu_data __percpu *sda; /* Per-CPU srcu_data array. */
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unsigned long srcu_barrier_seq; /* srcu_barrier seq #. */
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struct mutex srcu_barrier_mutex; /* Serialize barrier ops. */
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struct completion srcu_barrier_completion;
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/* Awaken barrier rq at end. */
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atomic_t srcu_barrier_cpu_cnt; /* # CPUs not yet posting a */
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/* callback for the barrier */
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/* operation. */
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struct delayed_work work;
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#ifdef CONFIG_DEBUG_LOCK_ALLOC
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struct lockdep_map dep_map;
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#endif /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */
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};
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/* Values for state variable (bottom bits of ->srcu_gp_seq). */
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#define SRCU_STATE_IDLE 0
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#define SRCU_STATE_SCAN1 1
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#define SRCU_STATE_SCAN2 2
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#define __SRCU_STRUCT_INIT(name, pcpu_name) \
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{ \
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.sda = &pcpu_name, \
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.lock = __SPIN_LOCK_UNLOCKED(name.lock), \
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.srcu_gp_seq_needed = -1UL, \
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.work = __DELAYED_WORK_INITIALIZER(name.work, NULL, 0), \
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__SRCU_DEP_MAP_INIT(name) \
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}
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/*
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* Define and initialize a srcu struct at build time.
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* Do -not- call init_srcu_struct() nor cleanup_srcu_struct() on it.
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*
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* Note that although DEFINE_STATIC_SRCU() hides the name from other
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* files, the per-CPU variable rules nevertheless require that the
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* chosen name be globally unique. These rules also prohibit use of
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* DEFINE_STATIC_SRCU() within a function. If these rules are too
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* restrictive, declare the srcu_struct manually. For example, in
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* each file:
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*
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* static struct srcu_struct my_srcu;
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*
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* Then, before the first use of each my_srcu, manually initialize it:
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*
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* init_srcu_struct(&my_srcu);
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*
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* See include/linux/percpu-defs.h for the rules on per-CPU variables.
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*/
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#define __DEFINE_SRCU(name, is_static) \
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static DEFINE_PER_CPU(struct srcu_data, name##_srcu_data);\
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is_static struct srcu_struct name = __SRCU_STRUCT_INIT(name, name##_srcu_data)
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#define DEFINE_SRCU(name) __DEFINE_SRCU(name, /* not static */)
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#define DEFINE_STATIC_SRCU(name) __DEFINE_SRCU(name, static)
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void synchronize_srcu_expedited(struct srcu_struct *sp);
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void srcu_barrier(struct srcu_struct *sp);
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void srcu_torture_stats_print(struct srcu_struct *sp, char *tt, char *tf);
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#endif
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