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authorLinus Torvalds <torvalds@linux-foundation.org>2015-04-14 13:36:04 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2015-04-14 13:36:04 -0700
commit078838d56574694d0a4815d9c1b7f28e8844638b (patch)
tree0d8c72d9dc46b0d2e72073fb928ec08e14b02b76 /kernel/cpu.c
parenteeee78cf77df0450ca285a7cd6d73842181e825c (diff)
parent590ee7dbd569a012df705a5204fc5f1066f52b8c (diff)
Merge branch 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull RCU changes from Ingo Molnar: "The main changes in this cycle were: - changes permitting use of call_rcu() and friends very early in boot, for example, before rcu_init() is invoked. - add in-kernel API to enable and disable expediting of normal RCU grace periods. - improve RCU's handling of (hotplug-) outgoing CPUs. - NO_HZ_FULL_SYSIDLE fixes. - tiny-RCU updates to make it more tiny. - documentation updates. - miscellaneous fixes" * 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (58 commits) cpu: Provide smpboot_thread_init() on !CONFIG_SMP kernels as well cpu: Defer smpboot kthread unparking until CPU known to scheduler rcu: Associate quiescent-state reports with grace period rcu: Yet another fix for preemption and CPU hotplug rcu: Add diagnostics to grace-period cleanup rcutorture: Default to grace-period-initialization delays rcu: Handle outgoing CPUs on exit from idle loop cpu: Make CPU-offline idle-loop transition point more precise rcu: Eliminate ->onoff_mutex from rcu_node structure rcu: Process offlining and onlining only at grace-period start rcu: Move rcu_report_unblock_qs_rnp() to common code rcu: Rework preemptible expedited bitmask handling rcu: Remove event tracing from rcu_cpu_notify(), used by offline CPUs rcutorture: Enable slow grace-period initializations rcu: Provide diagnostic option to slow down grace-period initialization rcu: Detect stalls caused by failure to propagate up rcu_node tree rcu: Eliminate empty HOTPLUG_CPU ifdef rcu: Simplify sync_rcu_preempt_exp_init() rcu: Put all orphan-callback-related code under same comment rcu: Consolidate offline-CPU callback initialization ...
Diffstat (limited to 'kernel/cpu.c')
-rw-r--r--kernel/cpu.c38
1 files changed, 34 insertions, 4 deletions
diff --git a/kernel/cpu.c b/kernel/cpu.c
index 82eea9c5af61..94bbe4695232 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -411,8 +411,10 @@ static int __ref _cpu_down(unsigned int cpu, int tasks_frozen)
*
* Wait for the stop thread to go away.
*/
- while (!idle_cpu(cpu))
+ while (!per_cpu(cpu_dead_idle, cpu))
cpu_relax();
+ smp_mb(); /* Read from cpu_dead_idle before __cpu_die(). */
+ per_cpu(cpu_dead_idle, cpu) = false;
hotplug_cpu__broadcast_tick_pull(cpu);
/* This actually kills the CPU. */
@@ -451,6 +453,37 @@ out:
EXPORT_SYMBOL(cpu_down);
#endif /*CONFIG_HOTPLUG_CPU*/
+/*
+ * Unpark per-CPU smpboot kthreads at CPU-online time.
+ */
+static int smpboot_thread_call(struct notifier_block *nfb,
+ unsigned long action, void *hcpu)
+{
+ int cpu = (long)hcpu;
+
+ switch (action & ~CPU_TASKS_FROZEN) {
+
+ case CPU_ONLINE:
+ smpboot_unpark_threads(cpu);
+ break;
+
+ default:
+ break;
+ }
+
+ return NOTIFY_OK;
+}
+
+static struct notifier_block smpboot_thread_notifier = {
+ .notifier_call = smpboot_thread_call,
+ .priority = CPU_PRI_SMPBOOT,
+};
+
+void __cpuinit smpboot_thread_init(void)
+{
+ register_cpu_notifier(&smpboot_thread_notifier);
+}
+
/* Requires cpu_add_remove_lock to be held */
static int _cpu_up(unsigned int cpu, int tasks_frozen)
{
@@ -490,9 +523,6 @@ static int _cpu_up(unsigned int cpu, int tasks_frozen)
goto out_notify;
BUG_ON(!cpu_online(cpu));
- /* Wake the per cpu threads */
- smpboot_unpark_threads(cpu);
-
/* Now call notifier in preparation. */
cpu_notify(CPU_ONLINE | mod, hcpu);