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time: Fix change_clocksource locking 

change_clocksource() fails to grab locks or call timekeeping_update(),
which leaves a race window for time inconsistencies.

This adds proper locking and a call to timekeeping_update() to fix this.

CC: Andy Lutomirski <luto@amacapital.net>
CC: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: John Stultz <john.stultz@linaro.org>
This commit is contained in:
John Stultz 2012-03-14 16:38:15 -07:00
parent a939e817aa
commit f695cf9483
1 changed files with 7 additions and 0 deletions
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7
kernel/time/timekeeping.c
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@ -448,9 +448,12 @@ EXPORT_SYMBOL(timekeeping_inject_offset);
static int change_clocksource(void *data)
{
struct clocksource *new, *old;
unsigned long flags;
new = (struct clocksource *) data;
write_seqlock_irqsave(&timekeeper.lock, flags);
timekeeping_forward_now();
if (!new->enable || new->enable(new) == 0) {
old = timekeeper.clock;
@ -458,6 +461,10 @@ static int change_clocksource(void *data)
if (old->disable)
old->disable(old);
}
timekeeping_update(true);
write_sequnlock_irqrestore(&timekeeper.lock, flags);
return 0;
}