[v3,14/45] timer: Use get/put_online_cpus_atomic() to prevent CPU offline

Message ID 20130627195446.29830.13065.stgit@srivatsabhat.in.ibm.com
State Not Applicable, archived
Delegated to: David Miller
Headers show

Commit Message

Srivatsa S. Bhat June 27, 2013, 7:54 p.m.
Once stop_machine() is gone from the CPU offline path, we won't be able
to depend on disabling preemption to prevent CPUs from going offline
from under us.

Use the get/put_online_cpus_atomic() APIs to prevent CPUs from going
offline, while invoking from atomic context.

Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>

 kernel/timer.c |    4 ++++
 1 file changed, 4 insertions(+)

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diff --git a/kernel/timer.c b/kernel/timer.c
index 15ffdb3..5db594c 100644
--- a/kernel/timer.c
+++ b/kernel/timer.c
@@ -729,6 +729,7 @@  __mod_timer(struct timer_list *timer, unsigned long expires,
+	get_online_cpus_atomic();
 	base = lock_timer_base(timer, &flags);
 	ret = detach_if_pending(timer, base, false);
@@ -768,6 +769,7 @@  __mod_timer(struct timer_list *timer, unsigned long expires,
 	spin_unlock_irqrestore(&base->lock, flags);
+	put_online_cpus_atomic();
 	return ret;
@@ -926,6 +928,7 @@  void add_timer_on(struct timer_list *timer, int cpu)
 	BUG_ON(timer_pending(timer) || !timer->function);
+	get_online_cpus_atomic();
 	spin_lock_irqsave(&base->lock, flags);
 	timer_set_base(timer, base);
 	debug_activate(timer, timer->expires);
@@ -940,6 +943,7 @@  void add_timer_on(struct timer_list *timer, int cpu)
 	spin_unlock_irqrestore(&base->lock, flags);
+	put_online_cpus_atomic();