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rcu,cleanup: move synchronize_sched_expedited() out of sched.c

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The first version of synchronize_sched_expedited() used the migration
code in the scheduler, and was therefore implemented in kernel/sched.c.
However, the more recent version of this code no longer uses the
migration code, so this commit moves it to the main RCU source files.

Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
This commit is contained in:
Lai Jiangshan 2010-10-21 11:29:05 +08:00 committed by Paul E. McKenney
parent deb7a41815
commit 7b27d5475f
5 changed files with 77 additions and 70 deletions
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1
include/linux/rcupdate.h
View File

@ -66,7 +66,6 @@ extern void call_rcu_sched(struct rcu_head *head,
extern void synchronize_sched(void);
extern void rcu_barrier_bh(void);
extern void rcu_barrier_sched(void);
extern void synchronize_sched_expedited(void);
extern int sched_expedited_torture_stats(char *page);
static inline void __rcu_read_lock_bh(void)

5
include/linux/rcutiny.h
View File

@ -60,6 +60,11 @@ static inline void synchronize_rcu_bh_expedited(void)
synchronize_sched();
}
static inline void synchronize_sched_expedited(void)
{
synchronize_sched();
}
#ifdef CONFIG_TINY_RCU
static inline void rcu_preempt_note_context_switch(void)

1
include/linux/rcutree.h
View File

@ -48,6 +48,7 @@ static inline void exit_rcu(void)
#endif /* #else #ifdef CONFIG_TREE_PREEMPT_RCU */
extern void synchronize_rcu_bh(void);
extern void synchronize_sched_expedited(void);
extern void synchronize_rcu_expedited(void);
static inline void synchronize_rcu_bh_expedited(void)

71
kernel/rcutree_plugin.h
View File

@ -25,6 +25,7 @@
*/
#include <linux/delay.h>
#include <linux/stop_machine.h>
/*
* Check the RCU kernel configuration parameters and print informative
@ -1014,6 +1015,76 @@ static void __init __rcu_init_preempt(void)
#endif /* #else #ifdef CONFIG_TREE_PREEMPT_RCU */
#ifndef CONFIG_SMP
void synchronize_sched_expedited(void)
{
cond_resched();
}
EXPORT_SYMBOL_GPL(synchronize_sched_expedited);
#else /* #ifndef CONFIG_SMP */
static atomic_t synchronize_sched_expedited_count = ATOMIC_INIT(0);
static int synchronize_sched_expedited_cpu_stop(void *data)
{
/*
* There must be a full memory barrier on each affected CPU
* between the time that try_stop_cpus() is called and the
* time that it returns.
*
* In the current initial implementation of cpu_stop, the
* above condition is already met when the control reaches
* this point and the following smp_mb() is not strictly
* necessary. Do smp_mb() anyway for documentation and
* robustness against future implementation changes.
*/
smp_mb(); /* See above comment block. */
return 0;
}
/*
* Wait for an rcu-sched grace period to elapse, but use "big hammer"
* approach to force grace period to end quickly. This consumes
* significant time on all CPUs, and is thus not recommended for
* any sort of common-case code.
*
* Note that it is illegal to call this function while holding any
* lock that is acquired by a CPU-hotplug notifier. Failing to
* observe this restriction will result in deadlock.
*/
void synchronize_sched_expedited(void)
{
int snap, trycount = 0;
smp_mb(); /* ensure prior mod happens before capturing snap. */
snap = atomic_read(&synchronize_sched_expedited_count) + 1;
get_online_cpus();
while (try_stop_cpus(cpu_online_mask,
synchronize_sched_expedited_cpu_stop,
NULL) == -EAGAIN) {
put_online_cpus();
if (trycount++ < 10)
udelay(trycount * num_online_cpus());
else {
synchronize_sched();
return;
}
if (atomic_read(&synchronize_sched_expedited_count) - snap > 0) {
smp_mb(); /* ensure test happens before caller kfree */
return;
}
get_online_cpus();
}
atomic_inc(&synchronize_sched_expedited_count);
smp_mb__after_atomic_inc(); /* ensure post-GP actions seen after GP. */
put_online_cpus();
}
EXPORT_SYMBOL_GPL(synchronize_sched_expedited);
#endif /* #else #ifndef CONFIG_SMP */
#if !defined(CONFIG_RCU_FAST_NO_HZ)
/*

69
kernel/sched.c
View File

@ -9131,72 +9131,3 @@ struct cgroup_subsys cpuacct_subsys = {
};
#endif /* CONFIG_CGROUP_CPUACCT */
#ifndef CONFIG_SMP
void synchronize_sched_expedited(void)
{
barrier();
}
EXPORT_SYMBOL_GPL(synchronize_sched_expedited);
#else /* #ifndef CONFIG_SMP */
static atomic_t synchronize_sched_expedited_count = ATOMIC_INIT(0);
static int synchronize_sched_expedited_cpu_stop(void *data)
{
/*
* There must be a full memory barrier on each affected CPU
* between the time that try_stop_cpus() is called and the
* time that it returns.
*
* In the current initial implementation of cpu_stop, the
* above condition is already met when the control reaches
* this point and the following smp_mb() is not strictly
* necessary. Do smp_mb() anyway for documentation and
* robustness against future implementation changes.
*/
smp_mb(); /* See above comment block. */
return 0;
}
/*
* Wait for an rcu-sched grace period to elapse, but use "big hammer"
* approach to force grace period to end quickly. This consumes
* significant time on all CPUs, and is thus not recommended for
* any sort of common-case code.
*
* Note that it is illegal to call this function while holding any
* lock that is acquired by a CPU-hotplug notifier. Failing to
* observe this restriction will result in deadlock.
*/
void synchronize_sched_expedited(void)
{
int snap, trycount = 0;
smp_mb(); /* ensure prior mod happens before capturing snap. */
snap = atomic_read(&synchronize_sched_expedited_count) + 1;
get_online_cpus();
while (try_stop_cpus(cpu_online_mask,
synchronize_sched_expedited_cpu_stop,
NULL) == -EAGAIN) {
put_online_cpus();
if (trycount++ < 10)
udelay(trycount * num_online_cpus());
else {
synchronize_sched();
return;
}
if (atomic_read(&synchronize_sched_expedited_count) - snap > 0) {
smp_mb(); /* ensure test happens before caller kfree */
return;
}
get_online_cpus();
}
atomic_inc(&synchronize_sched_expedited_count);
smp_mb__after_atomic_inc(); /* ensure post-GP actions seen after GP. */
put_online_cpus();
}
EXPORT_SYMBOL_GPL(synchronize_sched_expedited);
#endif /* #else #ifndef CONFIG_SMP */