From: Alan Cox <alan@lxorguk.ukuu.org.uk>
To: Andi Kleen <andi@firstfloor.org>
Cc: Ingo Molnar <mingo@elte.hu>,
linux-kernel@vger.kernel.org,
Linus Torvalds <torvalds@linux-foundation.org>,
Andrew Morton <akpm@linux-foundation.org>,
Peter Zijlstra <a.p.zijlstra@chello.nl>,
Thomas Gleixner <tglx@linutronix.de>,
Alexander Viro <viro@ftp.linux.org.uk>
Subject: Re: [announce] "kill the Big Kernel Lock (BKL)" tree
Date: Wed, 14 May 2008 22:19:57 +0100 [thread overview]
Message-ID: <20080514221957.6edb2d60@core> (raw)
In-Reply-To: <482B5614.3060203@firstfloor.org>
> Most?
Yes
>
> >of the legacy users inflict that locking on other code - eg the ISN
> > use of the BKL directly impacts on the tty layer work.
>
> So you just stick unlock_kernel()/lock_kernel() around the call
> to TTY (or similar to the entry points)
It isn't that simple - I've spent a good deal of time working on it.
There are lots of paths that rely on interactions between modules. Eg we
found stuff racing between the pid structs tty internals and procfs that
happened to be saved by the BKL.
That in itself is a problem Ingo's stuff won't help with: We have lots of
"magic" accidental, undocumented and pot luck BKL locking semantics
between subsystems that are not even visible.
next prev parent reply other threads:[~2008-05-14 21:31 UTC|newest]
Thread overview: 78+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-05-14 17:49 [announce] "kill the Big Kernel Lock (BKL)" tree Ingo Molnar
2008-05-14 18:30 ` Andi Kleen
2008-05-14 21:00 ` Alan Cox
2008-05-14 21:13 ` Andi Kleen
2008-05-14 21:16 ` H. Peter Anvin
2008-05-14 21:17 ` Alan Cox
2008-05-14 21:19 ` Alan Cox [this message]
2008-05-14 21:45 ` Linus Torvalds
2008-05-14 22:03 ` Andi Kleen
2008-05-15 13:34 ` Alan Cox
2008-05-15 14:27 ` Andi Kleen
2008-05-15 15:36 ` Alan Cox
2008-05-16 10:21 ` Andi Kleen
2008-05-15 8:02 ` Ingo Molnar
2008-05-14 18:41 ` Linus Torvalds
2008-05-14 19:41 ` Ingo Molnar
2008-05-14 20:05 ` Frederik Deweerdt
2008-05-14 21:45 ` Jonathan Corbet
2008-05-14 21:39 ` Alan Cox
2008-05-14 21:56 ` Linus Torvalds
2008-05-14 22:07 ` Jonathan Corbet
2008-05-14 22:14 ` Linus Torvalds
2008-05-22 20:20 ` Alan Cox
2008-05-16 15:44 ` [PATCH, RFC] char dev BKL pushdown Jonathan Corbet
2008-05-16 15:49 ` Christoph Hellwig
2008-05-16 16:03 ` [PATCH] kill empty chardev open/release methods Christoph Hellwig
2008-05-16 16:24 ` Alan Cox
2008-05-16 20:55 ` Alan Cox
2008-05-18 19:46 ` Jonathan Corbet
2008-05-18 19:58 ` Alan Cox
2008-05-16 16:22 ` [PATCH, RFC] char dev BKL pushdown Alan Cox
2008-05-16 16:30 ` Linus Torvalds
2008-05-16 16:43 ` Jonathan Corbet
2008-05-17 21:15 ` Arnd Bergmann
2008-05-18 20:26 ` Jonathan Corbet
2008-05-19 23:07 ` Arnd Bergmann
[not found] ` <200805200111.47275.arnd@arndb.de>
2008-05-19 23:14 ` [PATCH 2/3, RFC] watchdog " Arnd Bergmann
2008-05-20 6:20 ` Christoph Hellwig
2008-05-20 8:30 ` Arnd Bergmann
2008-05-20 15:47 ` Wim Van Sebroeck
2008-05-20 18:31 ` Alan Cox
2008-05-20 21:00 ` Arnd Bergmann
2008-05-22 9:34 ` Alan Cox
2008-05-20 9:08 ` Alan Cox
2008-05-20 8:42 ` Alan Cox
2008-05-19 23:26 ` [PATCH 1/3, RFC] misc char " Arnd Bergmann
2008-05-20 0:07 ` Mike Frysinger
2008-05-20 0:21 ` Jonathan Corbet
2008-05-20 0:46 ` Mike Frysinger
2008-05-20 8:46 ` Alan Cox
2008-05-20 23:01 ` Mike Frysinger
2008-05-20 23:25 ` Jonathan Corbet
2008-05-21 16:22 ` Mike Frysinger
2008-05-19 23:34 ` [PATCH 3/3, RFC] remove BKL from misc_open() Arnd Bergmann
2008-05-20 15:13 ` [PATCH, RFC] char dev BKL pushdown Jonathan Corbet
2008-05-20 17:21 ` Arnd Bergmann
2008-05-20 18:51 ` Alan Cox
2008-05-17 21:58 ` Linus Torvalds
2008-05-18 20:07 ` Jonathan Corbet
2008-05-14 22:11 ` [announce] "kill the Big Kernel Lock (BKL)" tree Andi Kleen
2008-05-14 22:16 ` Linus Torvalds
2008-05-14 22:21 ` Andi Kleen
2008-05-15 13:30 ` Alan Cox
2008-05-15 15:05 ` John Stoffel
2008-05-15 15:10 ` Andi Kleen
2008-05-15 15:18 ` John Stoffel
2008-05-15 15:45 ` Andi Kleen
2008-05-15 8:44 ` Jan Engelhardt
2008-05-15 14:54 ` Diego Calleja
2008-05-14 21:46 ` Alan Cox
2008-05-14 22:11 ` Linus Torvalds
2008-05-14 22:15 ` Andi Kleen
2008-05-15 17:41 ` Linus Torvalds
2008-05-15 20:27 ` Arjan van de Ven
2008-05-15 20:45 ` Peter Zijlstra
2008-05-15 21:22 ` Arjan van de Ven
2008-05-17 0:14 ` Kevin Winchester
2008-05-17 0:37 ` Kevin Winchester
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