From 6a8943d9ec2567572fca25cf69ad45844d0141a3 Mon Sep 17 00:00:00 2001 From: =?utf8?q?Arve=20Hj=C3=B8nnev=C3=A5g?= Date: Tue, 22 Nov 2011 18:24:51 -0800 Subject: [PATCH] rtc: Fix some bugs that allowed accumulating time drift in suspend/resume MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit 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 Signed-off-by: John Stultz --- drivers/rtc/class.c | 10 +++++----- 1 file 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; } -- 2.20.1