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Merge branch 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 

* 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  time: Fix stupid KERN_WARN compile issue
  rtc: Avoid accumulating time drift in suspend/resume
  time: Avoid accumulating time drift in suspend/resume
  time: Catch invalid timespec sleep values in __timekeeping_inject_sleeptime
This commit is contained in:
Linus Torvalds 2011-07-22 16:52:18 -07:00
parent a99a7d1436 cbaa51524b
commit 112ec46966
2 changed files with 76 additions and 17 deletions
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65
drivers/rtc/class.c
View File

@ -41,20 +41,41 @@ static void rtc_device_release(struct device *dev)
* system's wall clock; restore it on resume().
*/
static time_t oldtime;
static struct timespec oldts;
static struct timespec old_rtc, old_system, old_delta;
static int rtc_suspend(struct device *dev, pm_message_t mesg)
{
struct rtc_device *rtc = to_rtc_device(dev);
struct rtc_time tm;
struct timespec delta, delta_delta;
if (strcmp(dev_name(&rtc->dev), CONFIG_RTC_HCTOSYS_DEVICE) != 0)
return 0;
/* snapshot the current RTC and system time at suspend*/
rtc_read_time(rtc, &tm);
ktime_get_ts(&oldts);
rtc_tm_to_time(&tm, &oldtime);
getnstimeofday(&old_system);
rtc_tm_to_time(&tm, &old_rtc.tv_sec);
/*
* To avoid drift caused by repeated suspend/resumes,
* which each can add ~1 second drift error,
* try to compensate so the difference in system time
* and rtc time stays close to constant.
*/
delta = timespec_sub(old_system, old_rtc);
delta_delta = timespec_sub(delta, old_delta);
if (abs(delta_delta.tv_sec) >= 2) {
/*
* if delta_delta is too large, assume time correction
* has occured and set old_delta to the current delta.
*/
old_delta = delta;
} else {
/* Otherwise try to adjust old_system to compensate */
old_system = timespec_sub(old_system, delta_delta);
}
return 0;
}
@ -63,32 +84,42 @@ static int rtc_resume(struct device *dev)
{
struct rtc_device *rtc = to_rtc_device(dev);
struct rtc_time tm;
time_t newtime;
struct timespec time;
struct timespec newts;
struct timespec new_system, new_rtc;
struct timespec sleep_time;
if (strcmp(dev_name(&rtc->dev), CONFIG_RTC_HCTOSYS_DEVICE) != 0)
return 0;
ktime_get_ts(&newts);
/* snapshot the current rtc and system time at resume */
getnstimeofday(&new_system);
rtc_read_time(rtc, &tm);
if (rtc_valid_tm(&tm) != 0) {
pr_debug("%s: bogus resume time\n", dev_name(&rtc->dev));
return 0;
}
rtc_tm_to_time(&tm, &newtime);
if (newtime <= oldtime) {
if (newtime < oldtime)
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));
return 0;
}
/* calculate the RTC time delta */
set_normalized_timespec(&time, newtime - oldtime, 0);
/* subtract kernel time between rtc_suspend to rtc_resume */
time = timespec_sub(time, timespec_sub(newts, oldts));
/* calculate the RTC time delta (sleep time)*/
sleep_time = timespec_sub(new_rtc, old_rtc);
timekeeping_inject_sleeptime(&time);
/*
* Since these RTC suspend/resume handlers are not called
* at the very end of suspend or the start of resume,
* some run-time may pass on either sides of the sleep time
* so subtract kernel run-time between rtc_suspend to rtc_resume
* to keep things accurate.
*/
sleep_time = timespec_sub(sleep_time,
timespec_sub(new_system, old_system));
timekeeping_inject_sleeptime(&sleep_time);
return 0;
}

28
kernel/time/timekeeping.c
View File

@ -604,6 +604,12 @@ static struct timespec timekeeping_suspend_time;
*/
static void __timekeeping_inject_sleeptime(struct timespec *delta)
{
if (!timespec_valid(delta)) {
printk(KERN_WARNING "__timekeeping_inject_sleeptime: Invalid "
"sleep delta value!\n");
return;
}
xtime = timespec_add(xtime, *delta);
wall_to_monotonic = timespec_sub(wall_to_monotonic, *delta);
total_sleep_time = timespec_add(total_sleep_time, *delta);
@ -686,12 +692,34 @@ static void timekeeping_resume(void)
static int timekeeping_suspend(void)
{
unsigned long flags;
struct timespec delta, delta_delta;
static struct timespec old_delta;
read_persistent_clock(&timekeeping_suspend_time);
write_seqlock_irqsave(&xtime_lock, flags);
timekeeping_forward_now();
timekeeping_suspended = 1;
/*
* To avoid drift caused by repeated suspend/resumes,
* which each can add ~1 second drift error,
* try to compensate so the difference in system time
* and persistent_clock time stays close to constant.
*/
delta = timespec_sub(xtime, timekeeping_suspend_time);
delta_delta = timespec_sub(delta, old_delta);
if (abs(delta_delta.tv_sec) >= 2) {
/*
* if delta_delta is too large, assume time correction
* has occured and set old_delta to the current delta.
*/
old_delta = delta;
} else {
/* Otherwise try to adjust old_system to compensate */
timekeeping_suspend_time =
timespec_add(timekeeping_suspend_time, delta_delta);
}
write_sequnlock_irqrestore(&xtime_lock, flags);
clockevents_notify(CLOCK_EVT_NOTIFY_SUSPEND, NULL);