diff options
author | Ingo Molnar <mingo@elte.hu> | 2010-12-23 06:57:04 -0500 |
---|---|---|
committer | Ingo Molnar <mingo@elte.hu> | 2010-12-23 06:57:04 -0500 |
commit | 394f4528c523d88daabd50f883a8d6b164075555 (patch) | |
tree | b45a5b87a1ba9be8afe71f1db1537ff19e2b05d8 /kernel/sched.c | |
parent | 90a8a73c06cc32b609a880d48449d7083327e11a (diff) | |
parent | 3c2dcf2aed5ea22ecf65a9a871c4963faec421b3 (diff) |
Merge branch 'rcu/next' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-2.6-rcu into core/rcu
Diffstat (limited to 'kernel/sched.c')
-rw-r--r-- | kernel/sched.c | 69 |
1 files changed, 0 insertions, 69 deletions
diff --git a/kernel/sched.c b/kernel/sched.c index 297d1a0eedb0..e6f8f1254319 100644 --- a/kernel/sched.c +++ b/kernel/sched.c | |||
@@ -9534,72 +9534,3 @@ struct cgroup_subsys cpuacct_subsys = { | |||
9534 | }; | 9534 | }; |
9535 | #endif /* CONFIG_CGROUP_CPUACCT */ | 9535 | #endif /* CONFIG_CGROUP_CPUACCT */ |
9536 | 9536 | ||
9537 | #ifndef CONFIG_SMP | ||
9538 | |||
9539 | void synchronize_sched_expedited(void) | ||
9540 | { | ||
9541 | barrier(); | ||
9542 | } | ||
9543 | EXPORT_SYMBOL_GPL(synchronize_sched_expedited); | ||
9544 | |||
9545 | #else /* #ifndef CONFIG_SMP */ | ||
9546 | |||
9547 | static atomic_t synchronize_sched_expedited_count = ATOMIC_INIT(0); | ||
9548 | |||
9549 | static int synchronize_sched_expedited_cpu_stop(void *data) | ||
9550 | { | ||
9551 | /* | ||
9552 | * There must be a full memory barrier on each affected CPU | ||
9553 | * between the time that try_stop_cpus() is called and the | ||
9554 | * time that it returns. | ||
9555 | * | ||
9556 | * In the current initial implementation of cpu_stop, the | ||
9557 | * above condition is already met when the control reaches | ||
9558 | * this point and the following smp_mb() is not strictly | ||
9559 | * necessary. Do smp_mb() anyway for documentation and | ||
9560 | * robustness against future implementation changes. | ||
9561 | */ | ||
9562 | smp_mb(); /* See above comment block. */ | ||
9563 | return 0; | ||
9564 | } | ||
9565 | |||
9566 | /* | ||
9567 | * Wait for an rcu-sched grace period to elapse, but use "big hammer" | ||
9568 | * approach to force grace period to end quickly. This consumes | ||
9569 | * significant time on all CPUs, and is thus not recommended for | ||
9570 | * any sort of common-case code. | ||
9571 | * | ||
9572 | * Note that it is illegal to call this function while holding any | ||
9573 | * lock that is acquired by a CPU-hotplug notifier. Failing to | ||
9574 | * observe this restriction will result in deadlock. | ||
9575 | */ | ||
9576 | void synchronize_sched_expedited(void) | ||
9577 | { | ||
9578 | int snap, trycount = 0; | ||
9579 | |||
9580 | smp_mb(); /* ensure prior mod happens before capturing snap. */ | ||
9581 | snap = atomic_read(&synchronize_sched_expedited_count) + 1; | ||
9582 | get_online_cpus(); | ||
9583 | while (try_stop_cpus(cpu_online_mask, | ||
9584 | synchronize_sched_expedited_cpu_stop, | ||
9585 | NULL) == -EAGAIN) { | ||
9586 | put_online_cpus(); | ||
9587 | if (trycount++ < 10) | ||
9588 | udelay(trycount * num_online_cpus()); | ||
9589 | else { | ||
9590 | synchronize_sched(); | ||
9591 | return; | ||
9592 | } | ||
9593 | if (atomic_read(&synchronize_sched_expedited_count) - snap > 0) { | ||
9594 | smp_mb(); /* ensure test happens before caller kfree */ | ||
9595 | return; | ||
9596 | } | ||
9597 | get_online_cpus(); | ||
9598 | } | ||
9599 | atomic_inc(&synchronize_sched_expedited_count); | ||
9600 | smp_mb__after_atomic_inc(); /* ensure post-GP actions seen after GP. */ | ||
9601 | put_online_cpus(); | ||
9602 | } | ||
9603 | EXPORT_SYMBOL_GPL(synchronize_sched_expedited); | ||
9604 | |||
9605 | #endif /* #else #ifndef CONFIG_SMP */ | ||