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authorArve Hjønnevåg <arve@android.com>2011-11-23 06:24:51 +0400
committerJohn Stultz <john.stultz@linaro.org>2011-11-23 07:25:56 +0400
commit6a8943d9ec2567572fca25cf69ad45844d0141a3 (patch)
treed14768e0747bd4b44fb00131c9c79713033c51c5 /drivers/rtc/class.c
parentc0afabd3d553c521e003779c127143ffde55a16f (diff)
downloadlinux-6a8943d9ec2567572fca25cf69ad45844d0141a3.tar.xz
rtc: Fix some bugs that allowed accumulating time drift in suspend/resume
The current code checks if abs(delta_delta.tv_sec) is greater or equal to two before it discards the old delta value, but this can trigger at close to -1 seconds since -1.000000001 seconds is stored as tv_sec -2 and tv_nsec 999999999 in a normalized timespec. rtc_resume had an early return check if the rtc value had not changed since rtc_suspend. This effectivly stops time for the duration of the short sleep. Check if sleep_time is positive after all the adjustments have been applied instead since this allows the old_system adjustment in rtc_suspend to have an effect even for short sleep cycles. CC: stable@kernel.org Signed-off-by: Arve Hjønnevåg <arve@android.com> Signed-off-by: John Stultz <john.stultz@linaro.org>
Diffstat (limited to 'drivers/rtc/class.c')
-rw-r--r--drivers/rtc/class.c10
1 files changed, 5 insertions, 5 deletions
diff --git a/drivers/rtc/class.c b/drivers/rtc/class.c
index 01a7df5317c1..b82a1554cdc1 100644
--- a/drivers/rtc/class.c
+++ b/drivers/rtc/class.c
@@ -66,7 +66,7 @@ static int rtc_suspend(struct device *dev, pm_message_t mesg)
*/
delta = timespec_sub(old_system, old_rtc);
delta_delta = timespec_sub(delta, old_delta);
- if (abs(delta_delta.tv_sec) >= 2) {
+ if (delta_delta.tv_sec < -2 || delta_delta.tv_sec >= 2) {
/*
* if delta_delta is too large, assume time correction
* has occured and set old_delta to the current delta.
@@ -100,9 +100,8 @@ static int rtc_resume(struct device *dev)
rtc_tm_to_time(&tm, &new_rtc.tv_sec);
new_rtc.tv_nsec = 0;
- if (new_rtc.tv_sec <= old_rtc.tv_sec) {
- if (new_rtc.tv_sec < old_rtc.tv_sec)
- pr_debug("%s: time travel!\n", dev_name(&rtc->dev));
+ if (new_rtc.tv_sec < old_rtc.tv_sec) {
+ pr_debug("%s: time travel!\n", dev_name(&rtc->dev));
return 0;
}
@@ -119,7 +118,8 @@ static int rtc_resume(struct device *dev)
sleep_time = timespec_sub(sleep_time,
timespec_sub(new_system, old_system));
- timekeeping_inject_sleeptime(&sleep_time);
+ if (sleep_time.tv_sec >= 0)
+ timekeeping_inject_sleeptime(&sleep_time);
return 0;
}