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SubjectRe: [RFC 2/2] clocksource: don't suspend/resume when unused
On Fri, 16 Jan 2015, Alexandre Belloni wrote:

> There is no point in calling suspend/resume for unused
> clocksources.
>
> Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
> ---
> kernel/time/clocksource.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/kernel/time/clocksource.c b/kernel/time/clocksource.c
> index 920a4da58eb0..baea4e42ae90 100644
> --- a/kernel/time/clocksource.c
> +++ b/kernel/time/clocksource.c
> @@ -493,7 +493,7 @@ void clocksource_suspend(void)
> struct clocksource *cs;
>
> list_for_each_entry_reverse(cs, &clocksource_list, list)
> - if (cs->suspend)
> + if (cs->suspend && (cs->flags & CLOCK_SOURCE_USED))
> cs->suspend(cs);

This might be dangerous. If the clocksource has no enable/disable
callbacks, but suspend/resume, then you might leave it enabled across
suspend.

Thanks,

tglx



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