Re: [pm] fix time after suspend-to-*

[George Anzinger <george@mvista.com>]

Pavel Machek wrote:
> Hi!
> 
> 
>>>+static int pit_resume(struct sys_device *dev)
>>>+{
>>>+	if (got_clock_diff) {	/* Must know time zone in order to set clock */
>>>+		xtime.tv_sec = get_cmos_time() + clock_cmos_diff;
>>>+		xtime.tv_nsec = 0; 
>>>+	} 
>>>+	return 0;
>>>+}
>>>+
> 
> ...
> 
>>Forgive me, I'm not totally familiar w/ the sysfs/pm stuff, but normally
>>you need to have the xtime_lock to safely manipulate xtime. Also,
>>couldn't you just call settimeofday() instead?  The bit about manually
>>setting the timezone also confuses me, as we don't normally do this at
>>bootup in the kernel.  
>>
> 
> 
> I took it straight from apm.c... But it is well possible that it needs
> some locking. OTOH this runs with interrupts disabled, perhaps
> thats enough?

I lost (never saw) the first of this thread, BUT, if this is 2.6, I strongly 
recommend that settimeofday() NOT be called.  It will try to adjust 
wall_to_motonoic, but, as this appears to be a correction for time lost while 
sleeping, wall_to_monotonic should not change.

As to locking, ints off for UP, but you need the full lock for SMP systems.

-- 
George Anzinger   george@mvista.com
High-res-timers:  http://sourceforge.net/projects/high-res-timers/
Preemption patch: http://www.kernel.org/pub/linux/kernel/people/rml