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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: Thu, 16 Mar 2006 10:01:53 +0100	[thread overview]
Message-ID: <1142499713.29968.11.camel@localhost.localdomain> (raw)
In-Reply-To: <Pine.LNX.4.64.0603152055380.16802@scrub.home>

Roman,

> I have an idea what might have happened. You don't advance the pending 
> state, if the signal isn't queued, so that the pending state is screwed up 
> afterwards. Although I don't see how it could crash the kernel (it has 
> only the potential to mess up the timer queue via hrtimer_forward() a 
> bit), but I don't know what other patches were applied.

Good catch, but I dont see how it would trigger the bug.

> For example no current user restarts an active timer, which could be used 
> to simplify the locking.

How does this simplify the locking ? It just removes the
hrtimer_cancel() call in hrtimer_start() and makes the
switch_hrtimer_base() code a bit simpler. 

The general locking rules would be still the same and I dont see
increased flexibility at all.

> If we tightened a bit what a user is allowed to 
> do, we could gain flexibility on the other side, e.g. allow drivers to 
> create timer sources or how to integrate cpu timer.

-ENOPARSE. Can you please explain what "allow drivers to create timer
sources" means and why the above locking is in the way ?

	tglx



  reply	other threads:[~2006-03-16  9:01 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
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 [this message]
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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