256 lines
8.7 KiB
C
256 lines
8.7 KiB
C
/*
|
|
* Sleepable Read-Copy Update mechanism for mutual exclusion
|
|
*
|
|
* This program is free software; you can redistribute it and/or modify
|
|
* it under the terms of the GNU General Public License as published by
|
|
* the Free Software Foundation; either version 2 of the License, or
|
|
* (at your option) any later version.
|
|
*
|
|
* This program is distributed in the hope that it will be useful,
|
|
* but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
* GNU General Public License for more details.
|
|
*
|
|
* You should have received a copy of the GNU General Public License
|
|
* along with this program; if not, you can access it online at
|
|
* http://www.gnu.org/licenses/gpl-2.0.html.
|
|
*
|
|
* Copyright (C) IBM Corporation, 2006
|
|
* Copyright (C) Fujitsu, 2012
|
|
*
|
|
* Author: Paul McKenney <paulmck@us.ibm.com>
|
|
* Lai Jiangshan <laijs@cn.fujitsu.com>
|
|
*
|
|
* For detailed explanation of Read-Copy Update mechanism see -
|
|
* Documentation/RCU/ *.txt
|
|
*
|
|
*/
|
|
|
|
#ifndef _LINUX_SRCU_H
|
|
#define _LINUX_SRCU_H
|
|
|
|
#include <linux/mutex.h>
|
|
#include <linux/rcupdate.h>
|
|
#include <linux/workqueue.h>
|
|
|
|
struct srcu_struct_array {
|
|
unsigned long c[2];
|
|
unsigned long seq[2];
|
|
};
|
|
|
|
struct rcu_batch {
|
|
struct rcu_head *head, **tail;
|
|
};
|
|
|
|
#define RCU_BATCH_INIT(name) { NULL, &(name.head) }
|
|
|
|
struct srcu_struct {
|
|
unsigned long completed;
|
|
struct srcu_struct_array __percpu *per_cpu_ref;
|
|
spinlock_t queue_lock; /* protect ->batch_queue, ->running */
|
|
bool running;
|
|
/* callbacks just queued */
|
|
struct rcu_batch batch_queue;
|
|
/* callbacks try to do the first check_zero */
|
|
struct rcu_batch batch_check0;
|
|
/* callbacks done with the first check_zero and the flip */
|
|
struct rcu_batch batch_check1;
|
|
struct rcu_batch batch_done;
|
|
struct delayed_work work;
|
|
#ifdef CONFIG_DEBUG_LOCK_ALLOC
|
|
struct lockdep_map dep_map;
|
|
#endif /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */
|
|
};
|
|
|
|
#ifdef CONFIG_DEBUG_LOCK_ALLOC
|
|
|
|
int __init_srcu_struct(struct srcu_struct *sp, const char *name,
|
|
struct lock_class_key *key);
|
|
|
|
#define init_srcu_struct(sp) \
|
|
({ \
|
|
static struct lock_class_key __srcu_key; \
|
|
\
|
|
__init_srcu_struct((sp), #sp, &__srcu_key); \
|
|
})
|
|
|
|
#define __SRCU_DEP_MAP_INIT(srcu_name) .dep_map = { .name = #srcu_name },
|
|
#else /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */
|
|
|
|
int init_srcu_struct(struct srcu_struct *sp);
|
|
|
|
#define __SRCU_DEP_MAP_INIT(srcu_name)
|
|
#endif /* #else #ifdef CONFIG_DEBUG_LOCK_ALLOC */
|
|
|
|
void process_srcu(struct work_struct *work);
|
|
|
|
#define __SRCU_STRUCT_INIT(name) \
|
|
{ \
|
|
.completed = -300, \
|
|
.per_cpu_ref = &name##_srcu_array, \
|
|
.queue_lock = __SPIN_LOCK_UNLOCKED(name.queue_lock), \
|
|
.running = false, \
|
|
.batch_queue = RCU_BATCH_INIT(name.batch_queue), \
|
|
.batch_check0 = RCU_BATCH_INIT(name.batch_check0), \
|
|
.batch_check1 = RCU_BATCH_INIT(name.batch_check1), \
|
|
.batch_done = RCU_BATCH_INIT(name.batch_done), \
|
|
.work = __DELAYED_WORK_INITIALIZER(name.work, process_srcu, 0),\
|
|
__SRCU_DEP_MAP_INIT(name) \
|
|
}
|
|
|
|
/*
|
|
* define and init a srcu struct at build time.
|
|
* dont't call init_srcu_struct() nor cleanup_srcu_struct() on it.
|
|
*/
|
|
#define __DEFINE_SRCU(name, is_static) \
|
|
static DEFINE_PER_CPU(struct srcu_struct_array, name##_srcu_array);\
|
|
is_static struct srcu_struct name = __SRCU_STRUCT_INIT(name)
|
|
#define DEFINE_SRCU(name) __DEFINE_SRCU(name, /* not static */)
|
|
#define DEFINE_STATIC_SRCU(name) __DEFINE_SRCU(name, static)
|
|
|
|
/**
|
|
* call_srcu() - Queue a callback for invocation after an SRCU grace period
|
|
* @sp: srcu_struct in queue the callback
|
|
* @head: structure to be used for queueing the SRCU callback.
|
|
* @func: function to be invoked after the SRCU grace period
|
|
*
|
|
* The callback function will be invoked some time after a full SRCU
|
|
* grace period elapses, in other words after all pre-existing SRCU
|
|
* read-side critical sections have completed. However, the callback
|
|
* function might well execute concurrently with other SRCU read-side
|
|
* critical sections that started after call_srcu() was invoked. SRCU
|
|
* read-side critical sections are delimited by srcu_read_lock() and
|
|
* srcu_read_unlock(), and may be nested.
|
|
*
|
|
* The callback will be invoked from process context, but must nevertheless
|
|
* be fast and must not block.
|
|
*/
|
|
void call_srcu(struct srcu_struct *sp, struct rcu_head *head,
|
|
void (*func)(struct rcu_head *head));
|
|
|
|
void cleanup_srcu_struct(struct srcu_struct *sp);
|
|
int __srcu_read_lock(struct srcu_struct *sp) __acquires(sp);
|
|
void __srcu_read_unlock(struct srcu_struct *sp, int idx) __releases(sp);
|
|
void synchronize_srcu(struct srcu_struct *sp);
|
|
void synchronize_srcu_expedited(struct srcu_struct *sp);
|
|
unsigned long srcu_batches_completed(struct srcu_struct *sp);
|
|
void srcu_barrier(struct srcu_struct *sp);
|
|
|
|
#ifdef CONFIG_DEBUG_LOCK_ALLOC
|
|
|
|
/**
|
|
* srcu_read_lock_held - might we be in SRCU read-side critical section?
|
|
*
|
|
* If CONFIG_DEBUG_LOCK_ALLOC is selected, returns nonzero iff in an SRCU
|
|
* read-side critical section. In absence of CONFIG_DEBUG_LOCK_ALLOC,
|
|
* this assumes we are in an SRCU read-side critical section unless it can
|
|
* prove otherwise.
|
|
*
|
|
* Checks debug_lockdep_rcu_enabled() to prevent false positives during boot
|
|
* and while lockdep is disabled.
|
|
*
|
|
* Note that SRCU is based on its own statemachine and it doesn't
|
|
* relies on normal RCU, it can be called from the CPU which
|
|
* is in the idle loop from an RCU point of view or offline.
|
|
*/
|
|
static inline int srcu_read_lock_held(struct srcu_struct *sp)
|
|
{
|
|
if (!debug_lockdep_rcu_enabled())
|
|
return 1;
|
|
return lock_is_held(&sp->dep_map);
|
|
}
|
|
|
|
#else /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */
|
|
|
|
static inline int srcu_read_lock_held(struct srcu_struct *sp)
|
|
{
|
|
return 1;
|
|
}
|
|
|
|
#endif /* #else #ifdef CONFIG_DEBUG_LOCK_ALLOC */
|
|
|
|
/**
|
|
* srcu_dereference_check - fetch SRCU-protected pointer for later dereferencing
|
|
* @p: the pointer to fetch and protect for later dereferencing
|
|
* @sp: pointer to the srcu_struct, which is used to check that we
|
|
* really are in an SRCU read-side critical section.
|
|
* @c: condition to check for update-side use
|
|
*
|
|
* If PROVE_RCU is enabled, invoking this outside of an RCU read-side
|
|
* critical section will result in an RCU-lockdep splat, unless @c evaluates
|
|
* to 1. The @c argument will normally be a logical expression containing
|
|
* lockdep_is_held() calls.
|
|
*/
|
|
#define srcu_dereference_check(p, sp, c) \
|
|
__rcu_dereference_check((p), (c) || srcu_read_lock_held(sp), __rcu)
|
|
|
|
/**
|
|
* srcu_dereference - fetch SRCU-protected pointer for later dereferencing
|
|
* @p: the pointer to fetch and protect for later dereferencing
|
|
* @sp: pointer to the srcu_struct, which is used to check that we
|
|
* really are in an SRCU read-side critical section.
|
|
*
|
|
* Makes rcu_dereference_check() do the dirty work. If PROVE_RCU
|
|
* is enabled, invoking this outside of an RCU read-side critical
|
|
* section will result in an RCU-lockdep splat.
|
|
*/
|
|
#define srcu_dereference(p, sp) srcu_dereference_check((p), (sp), 0)
|
|
|
|
/**
|
|
* srcu_read_lock - register a new reader for an SRCU-protected structure.
|
|
* @sp: srcu_struct in which to register the new reader.
|
|
*
|
|
* Enter an SRCU read-side critical section. Note that SRCU read-side
|
|
* critical sections may be nested. However, it is illegal to
|
|
* call anything that waits on an SRCU grace period for the same
|
|
* srcu_struct, whether directly or indirectly. Please note that
|
|
* one way to indirectly wait on an SRCU grace period is to acquire
|
|
* a mutex that is held elsewhere while calling synchronize_srcu() or
|
|
* synchronize_srcu_expedited().
|
|
*
|
|
* Note that srcu_read_lock() and the matching srcu_read_unlock() must
|
|
* occur in the same context, for example, it is illegal to invoke
|
|
* srcu_read_unlock() in an irq handler if the matching srcu_read_lock()
|
|
* was invoked in process context.
|
|
*/
|
|
static inline int srcu_read_lock(struct srcu_struct *sp) __acquires(sp)
|
|
{
|
|
int retval;
|
|
|
|
preempt_disable();
|
|
retval = __srcu_read_lock(sp);
|
|
preempt_enable();
|
|
rcu_lock_acquire(&(sp)->dep_map);
|
|
return retval;
|
|
}
|
|
|
|
/**
|
|
* srcu_read_unlock - unregister a old reader from an SRCU-protected structure.
|
|
* @sp: srcu_struct in which to unregister the old reader.
|
|
* @idx: return value from corresponding srcu_read_lock().
|
|
*
|
|
* Exit an SRCU read-side critical section.
|
|
*/
|
|
static inline void srcu_read_unlock(struct srcu_struct *sp, int idx)
|
|
__releases(sp)
|
|
{
|
|
rcu_lock_release(&(sp)->dep_map);
|
|
__srcu_read_unlock(sp, idx);
|
|
}
|
|
|
|
/**
|
|
* smp_mb__after_srcu_read_unlock - ensure full ordering after srcu_read_unlock
|
|
*
|
|
* Converts the preceding srcu_read_unlock into a two-way memory barrier.
|
|
*
|
|
* Call this after srcu_read_unlock, to guarantee that all memory operations
|
|
* that occur after smp_mb__after_srcu_read_unlock will appear to happen after
|
|
* the preceding srcu_read_unlock.
|
|
*/
|
|
static inline void smp_mb__after_srcu_read_unlock(void)
|
|
{
|
|
/* __srcu_read_unlock has smp_mb() internally so nothing to do here. */
|
|
}
|
|
|
|
#endif
|