From: Roman Zippel <zippel@linux-m68k.org>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: Linus Torvalds <torvalds@osdl.org>,
LKML <linux-kernel@vger.kernel.org>, Ingo Molnar <mingo@elte.hu>,
George Anzinger <george@wildturkeyranch.net>,
Steven Rostedt <rostedt@goodmis.org>,
Andrew Morton <akpm@osdl.org>
Subject: Re: [PATCH 4/7] [hrtimers] Fix posix-timer requeue race
Date: Fri, 20 Jan 2006 12:36:26 +0100 (CET) [thread overview]
Message-ID: <Pine.LNX.4.61.0601201218530.11765@scrub.home> (raw)
In-Reply-To: <20060120021342.813743000@tglx.tec.linutronix.de>
Hi,
On Fri, 20 Jan 2006, Thomas Gleixner wrote:
> CPU0 expires a posix-timer and runs the callback function.
> The signal is queued.
> After releasing the posix-timer lock and before returning to
> hrtimer_run_queue CPU0 gets interrupted.
> CPU1 delivers the queued signal and rearms the timer.
> CPU0 comes back to hrtimer_run_queue and sets the timer state to expired.
> The next modification of the timer can result in an oops, because the state
> information is wrong.
Thomas, this is exactly what I meant with overloaded state machines,
enumerated states are very hard to get right with concurrent processes.
Please get rid of the state field and at least use a flag field instead.
bye, Roman
next prev parent reply other threads:[~2006-01-20 11:36 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-01-20 2:55 [PATCH 0/7] hrtimers updates Thomas Gleixner
2006-01-20 2:55 ` [PATCH 1/7] [hrtimers] Fixup itimer conversion Thomas Gleixner
2006-01-20 2:55 ` [PATCH 2/7] [hrtimers] Fix possible use of NULL pointer in posix-timers Thomas Gleixner
2006-01-20 2:55 ` [PATCH 3/7] [hrtimers] Fix oldvalue return in setitimer Thomas Gleixner
2006-01-24 21:56 ` Orion Poplawski
2006-01-25 6:56 ` Thomas Gleixner
2006-01-20 2:55 ` [PATCH 4/7] [hrtimers] Fix posix-timer requeue race Thomas Gleixner
2006-01-20 11:36 ` Roman Zippel [this message]
2006-01-20 2:55 ` [PATCH 5/7] [hrtimers] Cleanups and simplifications Thomas Gleixner
2006-01-20 2:55 ` [PATCH 6/7] [hrtimers] Add back lost credit lines Thomas Gleixner
2006-01-20 2:55 ` [PATCH 7/7] [hrtimers] Set correct initial expiry time for relative SIGEV_NONE timers Thomas Gleixner
2006-01-20 5:11 ` Andrew Morton
2006-01-20 9:49 ` Thomas Gleixner
2006-01-20 16:33 ` George Anzinger
2006-01-20 16:58 ` Thomas Gleixner
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