clocksource: Defer override invalidation unless clock is unstable
authorKyle Walker <kwalker@redhat.com>
Sat, 6 Aug 2016 16:07:30 +0000 (12:07 -0400)
committerJohn Stultz <john.stultz@linaro.org>
Wed, 31 Aug 2016 21:43:33 +0000 (14:43 -0700)
commit36374583f9084cdab4b5dcf5521a3ce55bebb9fa
tree9db17d8912137a810530add26d78f7d67e8462cf
parentb4d90e9f1ef1f19dcb2b1b1942c786c9c4225460
clocksource: Defer override invalidation unless clock is unstable

Clocksources don't get the VALID_FOR_HRES flag until they have been
checked by a watchdog. However, when using an override, the
clocksource_select logic will clear the override value if the
clocksource is not marked VALID_FOR_HRES during that inititial check.
When using the boot arguments clocksource=<foo>, this selection can
run before the watchdog, and can cause the override to be incorrectly
cleared.

To address this condition, the override_name is only invalidated for
unstable clocksources. Otherwise, the override is left intact until after
the watchdog has validated the clocksource as stable/unstable.

Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Kyle Walker <kwalker@redhat.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
kernel/time/clocksource.c