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authorIngo Molnar <mingo@elte.hu>2010-12-23 06:57:04 -0500
committerIngo Molnar <mingo@elte.hu>2010-12-23 06:57:04 -0500
commit394f4528c523d88daabd50f883a8d6b164075555 (patch)
treeb45a5b87a1ba9be8afe71f1db1537ff19e2b05d8 /kernel/sched.c
parent90a8a73c06cc32b609a880d48449d7083327e11a (diff)
parent3c2dcf2aed5ea22ecf65a9a871c4963faec421b3 (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.c69
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
9539void synchronize_sched_expedited(void)
9540{
9541 barrier();
9542}
9543EXPORT_SYMBOL_GPL(synchronize_sched_expedited);
9544
9545#else /* #ifndef CONFIG_SMP */
9546
9547static atomic_t synchronize_sched_expedited_count = ATOMIC_INIT(0);
9548
9549static 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 */
9576void 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}
9603EXPORT_SYMBOL_GPL(synchronize_sched_expedited);
9604
9605#endif /* #else #ifndef CONFIG_SMP */