From 7539a3b3d1f892dd97eaf094134d7de55c13befe Mon Sep 17 00:00:00 2001 From: "Rafael J. Wysocki" Date: Sun, 13 Dec 2009 00:07:30 +0100 Subject: [PATCH] sched: Make wakeup side and atomic variants of completion API irq safe Alan Stern noticed that all the wakeup side (and atomic) variants of the completion APIs should be irq safe, but the newly introduced completion_done() and try_wait_for_completion() aren't. The use of the irq unsafe variants in IRQ contexts can cause crashes/hangs. Fix the problem by making them use spin_lock_irqsave() and spin_lock_irqrestore(). Reported-by: Alan Stern Signed-off-by: Rafael J. Wysocki Cc: Linus Torvalds Cc: Zhang Rui Cc: pm list Cc: Peter Zijlstra Cc: David Chinner Cc: Lachlan McIlroy LKML-Reference: <200912130007.30541.rjw@sisk.pl> Signed-off-by: Ingo Molnar --- kernel/sched.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/kernel/sched.c b/kernel/sched.c index ff39cadf621e..8b3532f262d7 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -5908,14 +5908,15 @@ EXPORT_SYMBOL(wait_for_completion_killable); */ bool try_wait_for_completion(struct completion *x) { + unsigned long flags; int ret = 1; - spin_lock_irq(&x->wait.lock); + spin_lock_irqsave(&x->wait.lock, flags); if (!x->done) ret = 0; else x->done--; - spin_unlock_irq(&x->wait.lock); + spin_unlock_irqrestore(&x->wait.lock, flags); return ret; } EXPORT_SYMBOL(try_wait_for_completion); @@ -5930,12 +5931,13 @@ EXPORT_SYMBOL(try_wait_for_completion); */ bool completion_done(struct completion *x) { + unsigned long flags; int ret = 1; - spin_lock_irq(&x->wait.lock); + spin_lock_irqsave(&x->wait.lock, flags); if (!x->done) ret = 0; - spin_unlock_irq(&x->wait.lock); + spin_unlock_irqrestore(&x->wait.lock, flags); return ret; } EXPORT_SYMBOL(completion_done);