diff options
| author | John Stultz <john.stultz@linaro.org> | 2012-08-22 02:30:49 +0200 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2012-08-22 10:42:13 +0200 |
| commit | bf2ac312195155511a0f79325515cbb61929898a (patch) | |
| tree | 514057045cf52d3da13f551661131fd102f67376 /kernel/time/timekeeping.c | |
| parent | time: Avoid potential shift overflow with large shift values (diff) | |
| download | linux-bf2ac312195155511a0f79325515cbb61929898a.tar.xz linux-bf2ac312195155511a0f79325515cbb61929898a.zip | |
time: Avoid making adjustments if we haven't accumulated anything
If update_wall_time() is called and the current offset isn't large
enough to accumulate, avoid re-calling timekeeping_adjust which may
change the clock freq and can cause 1ns inconsistencies with
CLOCK_REALTIME_COARSE/CLOCK_MONOTONIC_COARSE.
Signed-off-by: John Stultz <john.stultz@linaro.org>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: stable@vger.kernel.org
Link: http://lkml.kernel.org/r/1345595449-34965-5-git-send-email-john.stultz@linaro.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'kernel/time/timekeeping.c')
| -rw-r--r-- | kernel/time/timekeeping.c | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c index a5a9389c4c30..0c1485e42be6 100644 --- a/kernel/time/timekeeping.c +++ b/kernel/time/timekeeping.c @@ -1152,6 +1152,10 @@ static void update_wall_time(void) offset = (clock->read(clock) - clock->cycle_last) & clock->mask; #endif + /* Check if there's really nothing to do */ + if (offset < tk->cycle_interval) + goto out; + /* * With NO_HZ we may have to accumulate many cycle_intervals * (think "ticks") worth of time at once. To do this efficiently, |