From: Thomas Gleixner <tglx@linutronix.de>
To: Roman Zippel <zippel@linux-m68k.org>
Cc: Andrew Morton <akpm@osdl.org>,
LKML <linux-kernel@vger.kernel.org>, Ingo Molnar <mingo@elte.hu>
Subject: Re: [patch 5/8] hrtimer remove state field
Date: Sun, 12 Mar 2006 16:41:48 +0100 [thread overview]
Message-ID: <1142178108.19916.475.camel@localhost.localdomain> (raw)
In-Reply-To: <Pine.LNX.4.64.0603121608440.17704@scrub.home>
On Sun, 2006-03-12 at 16:17 +0100, Roman Zippel wrote:
> >
> > CPU 0
> > spin_unlock_irq(base->lock)
> > CPU1
> > signal is dequeued
> > timer is requeued
> > user space code is executed
> > user space code sets SIG_IGN
> > restart = fn();
> >
> > Now fn() calls send_sigqeue() which returns 1, resulting in ret =
> > HRTIMER_RESTART which leads to requeueing of an enqueued timer.
>
> I'm not quite sure I follow, when the timer is running no signal should be
> queued, so nothing can be dequeued and no new timer can be requeued.
> If that somehow is possible (although I don't see how), you'd found a bug
> in the signal/posix timer code, which should not be worked around in the
> hrtimer run queue.
How do you want to prevent that a signal is dequeued on one CPU while
the softirq expires the timer on another CPU ? This can not be
prevented.
Of course we can check hrtimer_active() in posix_timer_fn(), but I have
to check if there is a problem the other way round. I cook up a patch.
tglx
next prev parent reply other threads:[~2006-03-12 15:41 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-03-12 10:37 [patch 0/8] hrtimer updates Thomas Gleixner
2006-03-12 10:37 ` [patch 1/8] hrtimer optimize softirq runqueues Thomas Gleixner
2006-03-12 10:37 ` [patch 2/8] Pass current time to hrtimer_forward() Thomas Gleixner
2006-03-12 10:37 ` [patch 3/8] posix-timer cleanup common_timer_get() Thomas Gleixner
2006-03-12 10:37 ` [patch 4/8] hrtimer simplify nanosleep Thomas Gleixner
2006-03-12 10:37 ` [patch 5/8] hrtimer remove state field Thomas Gleixner
2006-03-12 12:13 ` Roman Zippel
2006-03-12 13:10 ` Thomas Gleixner
2006-03-12 13:26 ` Roman Zippel
2006-03-12 13:35 ` Thomas Gleixner
2006-03-12 13:55 ` Roman Zippel
2006-03-12 14:15 ` Thomas Gleixner
2006-03-12 14:30 ` Roman Zippel
2006-03-12 14:54 ` Thomas Gleixner
2006-03-12 15:17 ` Roman Zippel
2006-03-12 15:41 ` Thomas Gleixner [this message]
2006-03-12 16:00 ` Roman Zippel
2006-03-12 16:26 ` Thomas Gleixner
2006-03-12 16:57 ` [patch] hrtimer remove replace state check by BUG_ON Thomas Gleixner
2006-03-16 1:05 ` [patch 5/8] hrtimer remove state field Roman Zippel
2006-03-16 9:01 ` Thomas Gleixner
2006-03-17 22:07 ` Roman Zippel
2006-03-18 8:46 ` Thomas Gleixner
2006-03-12 10:37 ` [patch 6/8] Remove it_real_value calculation from proc/*/stat Thomas Gleixner
2006-03-12 10:37 ` [patch 7/8] Remove DEFINE_KTIME and ktime_to_clock_t() Thomas Gleixner
2006-03-12 10:37 ` [patch 8/8] Remove nsec_t typedef Thomas Gleixner
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