x86: Serialize SMP bootup CMOS accesses on rtc_lock
authorJan Beulich <JBeulich@novell.com>
Tue, 19 Jul 2011 10:39:03 +0000 (11:39 +0100)
committerIngo Molnar <mingo@elte.hu>
Thu, 21 Jul 2011 07:20:59 +0000 (09:20 +0200)
commitac619f4eba45da10053fc991f8a5d47b3be79fa3
treec1abddc5657dd6efa9a8e8ed2fb4303bd01643dc
parent7e794cb7e36ccdb8c44b8ca7738720625b7aa2da
x86: Serialize SMP bootup CMOS accesses on rtc_lock

With CPU hotplug, there is a theoretical race between other CMOS
(namely RTC) accesses and those done in the SMP secondary
processor bringup path.

I am unware of the problem having been noticed by anyone in practice,
but it would very likely be rather spurious and very hard to reproduce.
So to be on the safe side, acquire rtc_lock around those accesses.

Signed-off-by: Jan Beulich <jbeulich@novell.com>
Cc: John Stultz <john.stultz@linaro.org>
Link: http://lkml.kernel.org/r/4E257AE7020000780004E2FF@nat28.tlf.novell.com
Signed-off-by: Ingo Molnar <mingo@elte.hu>
arch/x86/include/asm/smpboot_hooks.h