From: Thomas Gleixner <tglx@linutronix.de>
To: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Steven Rostedt <rostedt@goodmis.org>,
Stanislav Meduna <stano@meduna.org>,
"linux-rt-users@vger.kernel.org" <linux-rt-users@vger.kernel.org>,
Linux ARM Kernel <linux-arm-kernel@lists.infradead.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Peter Zijlstra <peterz@infradead.org>
Subject: Re: BUG: spinlock trylock failure on UP, i.MX28 3.12.15-rt25
Date: Fri, 2 May 2014 21:36:15 +0200 (CEST) [thread overview]
Message-ID: <alpine.DEB.2.02.1405022134380.6261@ionos.tec.linutronix.de> (raw)
In-Reply-To: <alpine.DEB.2.02.1405022100351.6261@ionos.tec.linutronix.de>
On Fri, 2 May 2014, Thomas Gleixner wrote:
> On Fri, 2 May 2014, Sebastian Andrzej Siewior wrote:
> > * Steven Rostedt | 2014-04-22 14:16:50 [-0400]:
> > > /*
> > > * Called by the local, per-CPU timer interrupt on SMP.
> > > */
> > >@@ -1467,7 +1473,7 @@ void run_local_timers(void)
> > > return;
> > > }
> > >
> > >- if (!spin_do_trylock(&base->lock)) {
> > >+ if (timer_should_raise_softirq(&base->lock)) {
> > > raise_softirq(TIMER_SOFTIRQ);
> > > return;
> > > }
> >
> > Okay. So Peter said that it is okay to apply this since FULL_NO_HZ users
> > wouldn't complain on UP. I still wouldn't say it is broken but that is a
> > different story.
> > We have two users of this trylock. run_local_timers() which pops up
> > quite often (and you patched here) and the other is
> > get_next_timer_interrupt(). What do you suggest we do here? It is
> > basically the same thing.
>
> It's different as it CANNOT fail on UP. That's called from the idle
> code and there is no way that anything holds that lock on UP when idle
> runs.
So yeah, you are right, that it's called from irq_exit() so it needs
an annotation at least. Maybe it's really cleaner to make it #if SMP
as well just for clarity raisins.
Thanks,
tglx
next prev parent reply other threads:[~2014-05-02 19:36 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <534C3606.7010206@meduna.org>
2014-04-14 23:45 ` BUG: spinlock trylock failure on UP, i.MX28 3.12.15-rt25 Stanislav Meduna
2014-04-15 22:08 ` Stanislav Meduna
2014-04-17 16:29 ` BUG: spinlock trylock failure on UP - reverting timer patches helps Stanislav Meduna
2014-04-17 22:55 ` Stanislav Meduna
2014-04-17 23:10 ` jordan
2014-04-18 1:15 ` jordan
2014-04-18 14:45 ` Stanislav Meduna
2014-04-18 15:09 ` jordan
2014-04-22 11:54 ` BUG: spinlock trylock failure on UP, i.MX28 3.12.15-rt25 Sebastian Andrzej Siewior
2014-04-22 13:46 ` Steven Rostedt
2014-04-22 14:09 ` Peter Zijlstra
2014-04-23 8:10 ` Sebastian Andrzej Siewior
2014-04-23 8:50 ` Peter Zijlstra
2014-04-22 16:51 ` Sebastian Andrzej Siewior
2014-04-22 17:48 ` Steven Rostedt
2014-04-22 18:16 ` Steven Rostedt
2014-04-23 7:14 ` Sebastian Andrzej Siewior
2014-04-23 8:49 ` Peter Zijlstra
2014-04-23 12:15 ` Steven Rostedt
2014-05-02 18:38 ` Sebastian Andrzej Siewior
2014-05-02 19:01 ` Thomas Gleixner
2014-05-02 19:36 ` Thomas Gleixner [this message]
2014-05-02 19:37 ` Sebastian Andrzej Siewior
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