Messages in this thread Patch in this message | | | From | John Stultz <> | Subject | [PATCH 2/2] time: Fix change_clocksource locking | Date | Wed, 14 Mar 2012 16:58:56 -0700 |
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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> --- kernel/time/timekeeping.c | 7 +++++++ 1 files changed, 7 insertions(+), 0 deletions(-)
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c index 403c2a0..b53da5e 100644 --- a/kernel/time/timekeeping.c +++ b/kernel/time/timekeeping.c @@ -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; } -- 1.7.3.2.146.gca209
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