From: Oleg Nesterov <oleg@tv-sign.ru>
To: "Chen, Kenneth W" <kenneth.w.chen@intel.com>
Cc: linux-kernel@vger.kernel.org, Ingo Molnar <mingo@elte.hu>,
Christoph Lameter <christoph@lameter.com>,
Andrew Morton <akpm@osdl.org>
Subject: Re: [PATCH 0/5] timers: description
Date: Sun, 27 Mar 2005 14:08:06 +0400 [thread overview]
Message-ID: <42468606.280849C6@tv-sign.ru> (raw)
In-Reply-To: 200503261952.j2QJq1g27569@unix-os.sc.intel.com
"Chen, Kenneth W" wrote:
>
> Oleg Nesterov wrote on March 19, 2005 17:28:48
> > These patches are updated version of 'del_timer_sync: proof of
> > concept' 2 patches.
>
> I changed schedule_timeout() to call the new del_timer_sync instead of
> currently del_singleshot_timer_sync in attempt to stress these set of
> patches a bit more and I just observed a kernel hang.
>
> The symptom starts with lost network connectivity. It looks like the
> entire ethernet connections were gone, followed by blank screen on the
> console. I'm not sure whether it is a hard or soft hang, but system
> is inaccessible (blank screen and no network connection). I'm forced
> to do a reboot when that happens.
Very strange. I am running 2.6.11 + timer patches +
#define del_singleshot_timer_sync(t) del_timer_sync(t)
without any problems.
This timer is private to schedule_timeout(), it can't change
base, so del_timer_sync() should be "obviously correct" in
that case.
What kernel version? Could you try this stupid patch?
Oleg.
--- TST/kernel/timer.c~ 2005-03-27 16:47:20.000000000 +0400
+++ TST/kernel/timer.c 2005-03-27 17:16:32.000000000 +0400
@@ -352,27 +352,46 @@ EXPORT_SYMBOL(del_timer);
*/
int del_timer_sync(struct timer_list *timer)
{
+ unsigned long tout;
+ int running = 0, migrated = 0, done = 0;
int ret;
check_timer(timer);
+ preempt_disable();
+ tout = jiffies + 10;
+
ret = 0;
for (;;) {
unsigned long flags;
tvec_base_t *base;
base = timer_base(timer);
- if (!base)
+ if (!base) {
+ preempt_enable();
return ret;
+ }
+ if (time_after(jiffies, tout)) {
+ preempt_enable();
+ printk(KERN_ERR "del_timer_sync hang: %d %d %d %d\n",
+ running, migrated, done, ret);
+ dump_stack();
+ return 0;
+ }
spin_lock_irqsave(&base->lock, flags);
- if (base->running_timer == timer)
+ if (base->running_timer == timer) {
+ ++running;
goto unlock;
+ }
- if (timer_base(timer) != base)
+ if (timer_base(timer) != base) {
+ ++migrated;
goto unlock;
+ }
+ ++done;
if (timer_pending(timer)) {
list_del(&timer->entry);
ret = 1;
next prev parent reply other threads:[~2005-03-27 10:02 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-03-21 14:19 [PATCH 6/5] timers: enable irqs in __mod_timer() Oleg Nesterov
2005-03-22 5:43 ` Andrew Morton
2005-03-24 21:56 ` [PATCH 0/5] timers: description Chen, Kenneth W
2005-03-26 19:52 ` Chen, Kenneth W
2005-03-27 10:08 ` Oleg Nesterov [this message]
2005-03-28 19:12 ` Christoph Lameter
2005-03-29 11:27 ` Oleg Nesterov
2005-03-29 14:47 ` Christoph Lameter
-- strict thread matches above, loose matches on Subject: below --
2005-03-19 18:30 Oleg Nesterov
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