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Commit f695cf94 authored by John Stultz's avatar John Stultz
Browse files

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: default avatarJohn Stultz <john.stultz@linaro.org>
parent a939e817

kernel/time/timekeeping.c

+7 −0
Original line number Diff line number Diff line
@@ -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;

}