* [PATCH] rtc: lockdep fix/workaround
@ 2006-09-19 19:54 Peter Zijlstra
2006-09-20 8:21 ` [PATCH] rtc: lockdep fix Ingo Molnar
0 siblings, 1 reply; 4+ messages in thread
From: Peter Zijlstra @ 2006-09-19 19:54 UTC (permalink / raw)
To: linux-kernel; +Cc: Andrew Morton, Ingo Molnar, Arjan van de Ven
BUG: warning at kernel/lockdep.c:1816/trace_hardirqs_on() (Not tainted)
[<c04051ee>] show_trace_log_lvl+0x58/0x171
[<c0405802>] show_trace+0xd/0x10
[<c040591b>] dump_stack+0x19/0x1b
[<c043abee>] trace_hardirqs_on+0xa2/0x11e
[<c06143c3>] _spin_unlock_irq+0x22/0x26
[<c0541540>] rtc_get_rtc_time+0x32/0x176
[<c0419ba4>] hpet_rtc_interrupt+0x92/0x14d
[<c0450f94>] handle_IRQ_event+0x20/0x4d
[<c0451055>] __do_IRQ+0x94/0xef
[<c040678d>] do_IRQ+0x9e/0xbd
[<c0404a49>] common_interrupt+0x25/0x2c
DWARF2 unwinder stuck at common_interrupt+0x25/0x2c
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
---
drivers/char/rtc.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
Index: linux-2.6.17.noarch/drivers/char/rtc.c
===================================================================
--- linux-2.6.17.noarch.orig/drivers/char/rtc.c 2006-09-18 21:34:11.000000000 +0200
+++ linux-2.6.17.noarch/drivers/char/rtc.c 2006-09-18 21:35:03.000000000 +0200
@@ -209,11 +209,12 @@ static const unsigned char days_in_mo[]
*/
static inline unsigned char rtc_is_updating(void)
{
+ unsigned long flags;
unsigned char uip;
- spin_lock_irq(&rtc_lock);
+ spin_lock_irqsave(&rtc_lock, flags);
uip = (CMOS_READ(RTC_FREQ_SELECT) & RTC_UIP);
- spin_unlock_irq(&rtc_lock);
+ spin_unlock_irqrestore(&rtc_lock, flags);
return uip;
}
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] rtc: lockdep fix
2006-09-19 19:54 [PATCH] rtc: lockdep fix/workaround Peter Zijlstra
@ 2006-09-20 8:21 ` Ingo Molnar
2006-09-20 8:49 ` Arjan van de Ven
0 siblings, 1 reply; 4+ messages in thread
From: Ingo Molnar @ 2006-09-20 8:21 UTC (permalink / raw)
To: Peter Zijlstra; +Cc: linux-kernel, Andrew Morton, Arjan van de Ven
* Peter Zijlstra <a.p.zijlstra@chello.nl> wrote:
> BUG: warning at kernel/lockdep.c:1816/trace_hardirqs_on() (Not tainted)
> [<c04051ee>] show_trace_log_lvl+0x58/0x171
> [<c0405802>] show_trace+0xd/0x10
> [<c040591b>] dump_stack+0x19/0x1b
> [<c043abee>] trace_hardirqs_on+0xa2/0x11e
> [<c06143c3>] _spin_unlock_irq+0x22/0x26
> [<c0541540>] rtc_get_rtc_time+0x32/0x176
> [<c0419ba4>] hpet_rtc_interrupt+0x92/0x14d
> [<c0450f94>] handle_IRQ_event+0x20/0x4d
> [<c0451055>] __do_IRQ+0x94/0xef
> [<c040678d>] do_IRQ+0x9e/0xbd
> [<c0404a49>] common_interrupt+0x25/0x2c
ouch! That is a scenario that could lead to real lockups. Fix looks good
and necessary for v2.6.18 to me.
> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Ingo Molnar <mingo@elte.hu>
Ingo
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] rtc: lockdep fix
2006-09-20 8:49 ` Arjan van de Ven
@ 2006-09-20 8:47 ` Ingo Molnar
0 siblings, 0 replies; 4+ messages in thread
From: Ingo Molnar @ 2006-09-20 8:47 UTC (permalink / raw)
To: Arjan van de Ven; +Cc: Peter Zijlstra, linux-kernel, Andrew Morton
* Arjan van de Ven <arjan@linux.intel.com> wrote:
> >ouch! That is a scenario that could lead to real lockups. Fix looks
> >good and necessary for v2.6.18 to me.
>
> btw this entire code path is evil; the rtc_get_rtc_time() function can
> do really long delays which is unsuitable for being called in
> interrupt context!
yeah - but i dont think it triggers that often, and a fix for that
probably isnt for v2.6.18.
Ingo
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] rtc: lockdep fix
2006-09-20 8:21 ` [PATCH] rtc: lockdep fix Ingo Molnar
@ 2006-09-20 8:49 ` Arjan van de Ven
2006-09-20 8:47 ` Ingo Molnar
0 siblings, 1 reply; 4+ messages in thread
From: Arjan van de Ven @ 2006-09-20 8:49 UTC (permalink / raw)
To: Ingo Molnar; +Cc: Peter Zijlstra, linux-kernel, Andrew Morton
Ingo Molnar wrote:
> * Peter Zijlstra <a.p.zijlstra@chello.nl> wrote:
>
>> BUG: warning at kernel/lockdep.c:1816/trace_hardirqs_on() (Not tainted)
>> [<c04051ee>] show_trace_log_lvl+0x58/0x171
>> [<c0405802>] show_trace+0xd/0x10
>> [<c040591b>] dump_stack+0x19/0x1b
>> [<c043abee>] trace_hardirqs_on+0xa2/0x11e
>> [<c06143c3>] _spin_unlock_irq+0x22/0x26
>> [<c0541540>] rtc_get_rtc_time+0x32/0x176
>> [<c0419ba4>] hpet_rtc_interrupt+0x92/0x14d
>> [<c0450f94>] handle_IRQ_event+0x20/0x4d
>> [<c0451055>] __do_IRQ+0x94/0xef
>> [<c040678d>] do_IRQ+0x9e/0xbd
>> [<c0404a49>] common_interrupt+0x25/0x2c
>
> ouch! That is a scenario that could lead to real lockups. Fix looks good
> and necessary for v2.6.18 to me.
>
btw this entire code path is evil; the rtc_get_rtc_time() function can do really long delays
which is unsuitable for being called in interrupt context!
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2006-09-20 8:55 UTC | newest]
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2006-09-19 19:54 [PATCH] rtc: lockdep fix/workaround Peter Zijlstra
2006-09-20 8:21 ` [PATCH] rtc: lockdep fix Ingo Molnar
2006-09-20 8:49 ` Arjan van de Ven
2006-09-20 8:47 ` Ingo Molnar
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