On Tue, 2006-07-11 at 09:45 +0200, Ingo Molnar wrote:
>
> ouch! That's another HPET bug i believe. AFAICS rtc_get_rtc_time() is
> really not meant to be called from any sort of timer interrupt! In
> particular this looping code:
>
> while (rtc_is_updating() != 0 && jiffies - uip_watchdog < 2*HZ/100) {
> barrier();
> cpu_relax();
> }
Seeing this after reading the volatile thread and then Chase's patch:
([PATCH] Make cpu_relax() imply barrier() on all arches)
http://marc.theaimsgroup.com/?l=linux-kernel&m=115237514517594&w=2
(yes I'm a bit behind in my LKML reading... 1663 messages to go)
There's no reason to have a barrier in this loop.
-- Steve
Signed-off-by: Steven Rostedt <[email protected]>
Index: linux-2.6.18-rc1/drivers/char/rtc.c
===================================================================
--- linux-2.6.18-rc1.orig/drivers/char/rtc.c 2006-07-13 23:40:58.000000000 -0400
+++ linux-2.6.18-rc1/drivers/char/rtc.c 2006-07-13 23:41:06.000000000 -0400
@@ -1238,10 +1238,8 @@ void rtc_get_rtc_time(struct rtc_time *r
* Once the read clears, read the RTC time (again via ioctl). Easy.
*/
- while (rtc_is_updating() != 0 && jiffies - uip_watchdog < 2*HZ/100) {
- barrier();
+ while (rtc_is_updating() != 0 && jiffies - uip_watchdog < 2*HZ/100)
cpu_relax();
- }
/*
* Only the values that we read from the RTC are set. We leave
-
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