From 048a0e8f5e1d94c01a5fc70f5b2f2fd2f4527326 Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Thu, 26 Apr 2012 10:52:27 -0700 Subject: [PATCH] timer: Fix mod_timer_pinned() header comment The mod_timer_pinned() header comment states that it prevents timers from being migrated to a different CPU. This is not the case, instead, it ensures that the timer is posted to the current CPU, but does nothing to prevent CPU-hotplug operations from migrating the timer. This commit therefore brings the comment header into alignment with reality. Signed-off-by: Paul E. McKenney Signed-off-by: Paul E. McKenney Acked-by: Steven Rostedt --- kernel/timer.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/kernel/timer.c b/kernel/timer.c index a297ffcf888e..837c552fe838 100644 --- a/kernel/timer.c +++ b/kernel/timer.c @@ -861,7 +861,13 @@ EXPORT_SYMBOL(mod_timer); * * mod_timer_pinned() is a way to update the expire field of an * active timer (if the timer is inactive it will be activated) - * and not allow the timer to be migrated to a different CPU. + * and to ensure that the timer is scheduled on the current CPU. + * + * Note that this does not prevent the timer from being migrated + * when the current CPU goes offline. If this is a problem for + * you, use CPU-hotplug notifiers to handle it correctly, for + * example, cancelling the timer when the corresponding CPU goes + * offline. * * mod_timer_pinned(timer, expires) is equivalent to: * -- 2.39.5