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authorMatt Fleming <matt.fleming@intel.com>2011-09-21 16:08:03 +0200
committerIngo Molnar <mingo@elte.hu>2011-09-21 16:16:09 +0200
commit47997d756aa2a84ab577e1b0383cc12d582fc69c (patch)
tree9b5874e94a14f771a3e482fa09e1fc68785a9277 /kernel
parent9d037a777695993ec7437e5f451647dea7919d4c (diff)
downloadlinux-linaro-precise-47997d756aa2a84ab577e1b0383cc12d582fc69c.tar.gz
x86/rtc: Don't recursively acquire rtc_lock
A deadlock was introduced on x86 in commit ef68c8f87ed1 ("x86: Serialize EFI time accesses on rtc_lock") because efi_get_time() and friends can be called with rtc_lock already held by read_persistent_time(), e.g.: timekeeping_init() read_persistent_clock() <-- acquire rtc_lock efi_get_time() phys_efi_get_time() <-- acquire rtc_lock <DEADLOCK> To fix this let's push the locking down into the get_wallclock() and set_wallclock() implementations. Only the clock implementations that access the x86 RTC directly need to acquire rtc_lock, so it makes sense to push the locking down into the rtc, vrtc and efi code. The virtualization implementations don't require rtc_lock to be held because they provide their own serialization. Signed-off-by: Matt Fleming <matt.fleming@intel.com> Acked-by: Jan Beulich <jbeulich@novell.com> Acked-by: Avi Kivity <avi@redhat.com> [for the virtualization aspect] Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Zhang Rui <rui.zhang@intel.com> Cc: Josh Boyer <jwboyer@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel')
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