From: "Rafael J. Wysocki" Detect the situations in which the time after a resume from disk would be earlier than the time before the suspend and prevent them from happening on i386. Signed-off-by: Rafael J. Wysocki Acked-by: John Stultz Acked-by: Pavel Machek Signed-off-by: Andrew Morton --- arch/i386/kernel/time.c | 24 ++++++++++++++++++------ 1 file changed, 18 insertions(+), 6 deletions(-) diff -puN arch/i386/kernel/time.c~i386-detect-clock-skew-during-suspend arch/i386/kernel/time.c --- a/arch/i386/kernel/time.c~i386-detect-clock-skew-during-suspend +++ a/arch/i386/kernel/time.c @@ -285,16 +285,19 @@ void notify_arch_cmos_timer(void) mod_timer(&sync_cmos_timer, jiffies + 1); } -static long clock_cmos_diff, sleep_start; +static long clock_cmos_diff; +static unsigned long sleep_start; static int timer_suspend(struct sys_device *dev, pm_message_t state) { /* * Estimate time zone so that set_time can update the clock */ - clock_cmos_diff = -get_cmos_time(); + unsigned long ctime = get_cmos_time(); + + clock_cmos_diff = -ctime; clock_cmos_diff += get_seconds(); - sleep_start = get_cmos_time(); + sleep_start = ctime; return 0; } @@ -302,16 +305,25 @@ static int timer_resume(struct sys_devic { unsigned long flags; unsigned long sec; - unsigned long sleep_length; + unsigned long ctime = get_cmos_time(); + long sleep_length = (ctime - sleep_start) * HZ; struct timespec ts; + + if (sleep_length < 0) { + printk(KERN_WARNING "CMOS clock skew detected in timer resume!\n"); + /* The time after the resume must not be earlier than the time + * before the suspend or some nasty things will happen + */ + sleep_length = 0; + ctime = sleep_start; + } #ifdef CONFIG_HPET_TIMER if (is_hpet_enabled()) hpet_reenable(); #endif setup_pit_timer(); - sec = get_cmos_time() + clock_cmos_diff; - sleep_length = (get_cmos_time() - sleep_start) * HZ; + sec = ctime + clock_cmos_diff; ts.tv_sec = sec; ts.tv_nsec = 0; do_settimeofday(&ts); _