Messages in this thread Patch in this message | | | Date | Sat, 18 Sep 2010 11:58:36 -0700 | From | Greg KH <> | Subject | [072/123] sched: Make wakeup side and atomic variants of completion API irq safe |
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From: Rafael J.Wysocki <rjw@sisk.pl>
commit 7539a3b3d1f892dd97eaf094134d7de55c13befe upstream
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 <stern@rowland.harvard.edu> Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Zhang Rui <rui.zhang@intel.com> Cc: pm list <linux-pm@lists.linux-foundation.org> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: David Chinner <david@fromorbit.com> Cc: Lachlan McIlroy <lachlan@sgi.com> LKML-Reference: <200912130007.30541.rjw@sisk.pl> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Mike Galbraith <efault@gmx.de> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de> --- kernel/sched.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-)
--- a/kernel/sched.c +++ b/kernel/sched.c @@ -5947,14 +5947,15 @@ EXPORT_SYMBOL(wait_for_completion_killab */ 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); @@ -5969,12 +5970,13 @@ 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);
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