Messages in this thread | | | Date | Fri, 16 Jan 2015 11:39:16 +0100 | From | Daniel Lezcano <> | Subject | Re: [RFC 2/2] clocksource: don't suspend/resume when unused |
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On 01/16/2015 11:35 AM, Alexandre Belloni wrote: > On 16/01/2015 at 11:23:32 +0100, Thomas Gleixner wrote : >> 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. >> > > Isn't that already the case? > Right now, if you call clocksource_suspend, it doesn't matter whether > the clocksource has an enable or not, it will be suspended. Maybe I'm > mistaken but my patch doesn't seem to change that behaviour.
Actually, if there is no enable/disable callback, then CLOCK_SOURCE_USED will be never set, hence the condition will always fail and the suspend callback won't be called.
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