From: Arnd Bergmann <arnd@arndb.de>
To: Jan Harkes <jaharkes@cs.cmu.edu>
Cc: Christoph Hellwig <hch@infradead.org>,
Mikulas Patocka <mikulas@artax.karlin.mff.cuni.cz>,
Trond Myklebust <Trond.Myklebust@netapp.com>,
Petr Vandrovec <vandrove@vc.cvut.cz>,
Anders Larsen <al@alarsen.net>, Jan Kara <jack@suse.cz>,
Evgeniy Dushistov <dushistov@mail.ru>,
Ingo Molnar <mingo@elte.hu>, Samuel Ortiz <samuel@sortiz.org>,
Arnaldo Carvalho de Melo <acme@ghostprotocols.net>,
linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
Andrew Hendry <andrew.hendry@gmail.com>
Subject: Re: Remaining BKL users, what to do
Date: Thu, 16 Sep 2010 21:26:11 +0200 [thread overview]
Message-ID: <201009162126.11515.arnd@arndb.de> (raw)
In-Reply-To: <20100916190025.GG24296@cs.cmu.edu>
On Thursday 16 September 2010 21:00:25 Jan Harkes wrote:
> > Just removing the BKL without the Coda community seems like a heap
> > of pointless work.
>
> It depends, it might get rid of that mount lockup. There shouldn't be
> too much shared state because the kernel module mostly just forwards
> requests to userspace and the BKL right now seems to be mostly used to
> protects access to the upcall lists and could probably without too much
> trouble be replaced with a single 'global' (but Coda-only) or
> mount-point specific mutex.
Ok, that would be nice.
There are two strategies forward then based on the current code:
1. introduce a global or per-superblock mutex and convert all
instances of lock-kernel to that, then see what breaks (lockdep
helps here) and fix up all places where you get potential
deadlocks. The easiest replacement would be the existing superblock
mutex, doing s/lock_kernel()/lock_super(sb)/.
2. understand what data structures are actually being protected
by the BKL right now, then add proper locking around all accesses
to them and finally remove all uses of the BKL.
Arnd
next prev parent reply other threads:[~2010-09-16 19:26 UTC|newest]
Thread overview: 63+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-09-16 14:32 Remaining BKL users, what to do Arnd Bergmann
2010-09-16 14:49 ` Steven Rostedt
2010-09-16 18:32 ` Jens Axboe
2010-09-17 18:46 ` Arnd Bergmann
2010-09-16 15:04 ` Jan Kara
2010-09-16 21:26 ` Anton Altaparmakov
2010-09-17 10:45 ` Arnd Bergmann
2010-09-17 13:32 ` Christoph Hellwig
2010-09-17 13:50 ` Arnd Bergmann
2010-09-17 14:02 ` Christoph Hellwig
2010-09-17 14:56 ` Arnd Bergmann
2010-09-17 19:00 ` [PATCH] BKL: Remove BKL from isofs Arnd Bergmann
2010-09-20 10:58 ` Jan Kara
2010-09-20 11:13 ` Arnd Bergmann
2010-09-20 15:18 ` Jan Kara
2010-09-20 15:40 ` Alexander E. Patrakov
2010-09-20 15:50 ` Jan Kara
2010-09-16 15:07 ` Remaining BKL users, what to do Alan Cox
2010-09-16 20:08 ` David Miller
2010-09-16 16:09 ` Anders Larsen
2010-09-16 16:57 ` Samuel Ortiz
2010-09-16 20:08 ` David Miller
2010-09-16 19:00 ` Jan Harkes
2010-09-16 19:26 ` Arnd Bergmann [this message]
2010-09-20 1:25 ` [autofs] " Ian Kent
2010-10-18 15:42 ` [v2] " Arnd Bergmann
2010-10-18 16:19 ` Christoph Hellwig
2010-10-18 17:38 ` Arnd Bergmann
2010-10-18 18:43 ` [Ksummit-2010-discuss] " Greg KH
2010-10-18 23:00 ` Dave Airlie
2010-10-19 0:40 ` Greg KH
2010-10-19 0:57 ` Dave Airlie
2010-10-19 2:24 ` Greg KH
2010-10-19 2:45 ` Dave Airlie
2010-10-19 3:33 ` Steven Rostedt
2010-10-19 4:03 ` Dave Airlie
2010-10-19 5:00 ` Theodore Kilgore
2010-10-19 4:52 ` Dave Airlie
2010-10-19 7:26 ` Arnd Bergmann
2010-10-19 12:39 ` Steven Rostedt
2010-10-19 13:54 ` Paul Mundt
2010-10-19 13:26 ` Arnd Bergmann
2010-10-19 20:50 ` Dave Airlie
2010-10-20 16:14 ` Ville Syrjälä
2010-10-19 18:24 ` Valdis.Kletnieks
2010-10-19 19:37 ` Greg KH
2010-10-19 19:40 ` Oliver Neukum
2010-10-19 20:29 ` Greg KH
2010-10-19 20:38 ` Jiri Kosina
2010-10-19 20:41 ` Alan Cox
2010-10-19 20:48 ` Arnd Bergmann
2010-10-19 20:44 ` Arnd Bergmann
2010-10-20 4:43 ` Dave Young
2010-10-20 6:50 ` Arnd Bergmann
2010-11-02 1:21 ` Pavel Machek
2010-11-03 6:58 ` Pekka Enberg
2010-10-21 12:47 ` Christoph Hellwig
2010-10-21 13:38 ` Arnd Bergmann
2010-10-21 13:50 ` [PATCH 1/2] BKL: remove BKL from qnx4 Arnd Bergmann
2010-10-21 15:22 ` Anders Larsen
2010-10-21 13:51 ` [PATCH 2/2] BKL: remove BKL from freevxfs Arnd Bergmann
-- strict thread matches above, loose matches on Subject: below --
2010-09-17 23:21 Remaining BKL users, what to do Petr Vandrovec
2010-09-21 20:01 ` Arnd Bergmann
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