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From: Manfred Spraul <manfred@colorfullife.com>
To: Linus Torvalds <torvalds@transmeta.com>
Cc: "Martin J. Bligh" <mbligh@aracnet.com>,
	Anton Blanchard <anton@samba.org>, Andrew Morton <akpm@digeo.com>,
	Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Zwane Mwaikambo <zwane@holomorphy.com>
Subject: Re: more signal locking bugs?
Date: Sun, 16 Feb 2003 20:37:17 +0100	[thread overview]
Message-ID: <3E4FE86D.1010708@colorfullife.com> (raw)
In-Reply-To: <Pine.LNX.4.44.0302161119020.2952-100000@home.transmeta.com>

Linus Torvalds wrote:

>In short, everything really seems to be pointing that way: the current
>task lock simply _is_ broken, and has apparently always been broken (but
>the ABBA deadlock is just extremely rare in practice, since you have to
>get an interrupt at just the right point on one CPU, while you have the AB
>case on another).\
>
ABBA is not a deadlock, because linux read_locks permit recursive calls.

    read_lock(tasklist_lock);
    task_lock(tsk);
    read_lock(tasklist_lock);

Does not deadlock, nor any other ordering.

The tasklist_lock is never taken for write from bh or irq context.

--
    Manfred


  reply	other threads:[~2003-02-16 19:27 UTC|newest]

Thread overview: 37+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20030215172407.1fdd41fd.akpm@digeo.com>
2003-02-16  1:35 ` Fw: 2.5.61 oops running SDET Linus Torvalds
2003-02-16  2:09   ` Martin J. Bligh
2003-02-16  2:27     ` Linus Torvalds
2003-02-16  4:00       ` Martin J. Bligh
2003-02-16 13:05         ` Anton Blanchard
2003-02-16 16:39           ` Martin J. Bligh
2003-02-16 18:21             ` Linus Torvalds
2003-02-16 19:06               ` Martin J. Bligh
2003-02-16 19:17                 ` Linus Torvalds
2003-02-16 21:15                   ` Martin J. Bligh
2003-02-16 21:21                     ` Manfred Spraul
2003-02-16 22:34                       ` Linus Torvalds
2003-02-16 23:08                         ` Martin J. Bligh
2003-02-16 23:32                           ` Linus Torvalds
2003-02-16 19:18                 ` Manfred Spraul
2003-02-16 19:19                 ` more signal locking bugs? Martin J. Bligh
2003-02-16 19:24                   ` Linus Torvalds
2003-02-16 19:37                     ` Manfred Spraul [this message]
2003-02-16 19:42                       ` Linus Torvalds
2003-02-16 20:01                         ` Linus Torvalds
2003-02-16 20:07                         ` Manfred Spraul
2003-02-16 20:10                           ` Linus Torvalds
2003-02-16 20:23                             ` Manfred Spraul
2003-02-17  0:23                           ` Linus Torvalds
2003-02-17  2:05                             ` Martin J. Bligh
2003-02-17  2:39                               ` Martin J. Bligh
2003-02-17  3:53                                 ` Linus Torvalds
2003-02-17  5:07                                   ` Martin J. Bligh
2003-02-17  6:17                                   ` Martin J. Bligh
2003-02-17 17:09                                   ` Magnus Naeslund(f)
2003-02-17  3:54                                 ` [PATCH] fix secondary oops in sighand locking Martin J. Bligh
2003-02-17  6:36                             ` more signal locking bugs? Manfred Spraul
2003-02-17 19:06                               ` Linus Torvalds
2003-02-16 18:07         ` Fw: 2.5.61 oops running SDET Linus Torvalds
2003-02-16 18:26           ` Martin J. Bligh
2003-02-16 18:36             ` Martin J. Bligh
2003-02-16  2:48     ` Zwane Mwaikambo

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