Re: [PATCH] clean up FIXME in do_timer_interrupt

[George Anzinger]

Andrew Morton wrote:
> Lee Revell <rlrevell@xxxxxxxxxxx> wrote:
>
> > On Thu, 2005-03-10 at 00:42 -0800, George Anzinger wrote:
> >
> > > This patch changes the update of the cmos clock to be timer driven
> > > rather than poll driven by the timer interrupt function.  If the clock
> > > is not being synced to an outside source the timer is removed and thus
> > > system overhead is nill in that case.  The update frequency is still ~11
> > > minutes and missing the update window still causes a retry in 60
> > > seconds.
> >
> > No replies yet.  Are there any objections to this patch?
>
>
> Nope.  I think it's neat.  I queued it up.

I had a nightmare about ntp coming in at the "wrong" time resulting in a 
deadlock.  Attached locking changes will make me sleep better :)

--
George Anzinger   george@xxxxxxxxxx
High-res-timers:  http://sourceforge.net/projects/high-res-timers/
Source: MontaVista Software, Inc.
Type: Defect Fix 
Disposition: Pending
Description:

I was not happy with the locking on this.  Two changes:
1) Turn off irq while setting the clock.
2) Call the timer code only through the timer interface 
   (set a short timer to do it from the ntp call).

Signed-off-by: George Anzinger <george@xxxxxxxxxx>

 time.c |    6 +++---
 1 files changed, 3 insertions(+), 3 deletions(-)

Index: linux-2.6.12-rc/arch/i386/kernel/time.c
===================================================================
--- linux-2.6.12-rc.orig/arch/i386/kernel/time.c
+++ linux-2.6.12-rc/arch/i386/kernel/time.c
@@ -176,12 +176,12 @@ static int set_rtc_mmss(unsigned long no
 	int retval;
 
 	/* gets recalled with irq locally disabled */
-	spin_lock(&rtc_lock);
+	spin_lock_irq(&rtc_lock);
 	if (efi_enabled)
 		retval = efi_set_rtc_mmss(nowtime);
 	else
 		retval = mach_set_rtc_mmss(nowtime);
-	spin_unlock(&rtc_lock);
+	spin_unlock_irq(&rtc_lock);
 
 	return retval;
 }
@@ -338,7 +338,7 @@ static void sync_cmos_clock(unsigned lon
 }
 void notify_arch_cmos_timer(void)
 {
-	sync_cmos_clock(0);
+	mod_timer(&sync_cmos_timer, jiffies + 1);
 }
 static long clock_cmos_diff, sleep_start;