From 7d145aa3abf4d96c91f37c012facd5cfbb9010d1 Mon Sep 17 00:00:00 2001 From: Rafael J. Wysocki Date: Mon, 25 Sep 2006 23:32:57 -0700 Subject: [PATCH] i386: Detect clock skew during suspend 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 Signed-off-by: Linus Torvalds --- arch/i386/kernel/time.c | 24 ++++++++++++++++++------ 1 file changed, 18 insertions(+), 6 deletions(-) (limited to 'arch/i386') diff --git a/arch/i386/kernel/time.c b/arch/i386/kernel/time.c index 6f333e7fb23c..1302e4ab3c4f 100644 --- a/arch/i386/kernel/time.c +++ b/arch/i386/kernel/time.c @@ -270,16 +270,19 @@ 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; } @@ -287,16 +290,25 @@ static int timer_resume(struct sys_device *dev) { 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); -- cgit v1.2.3