From: Arnd Bergmann <arnd@arndb.de>
To: Vasiliy Kulikov <segooon@gmail.com>
Cc: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>,
David Woodhouse <David.Woodhouse@intel.com>,
Nicolas Pitre <nico@fluxnic.net>,
Hans-Christian Egtvedt <hans-christian.egtvedt@atmel.com>,
Jiri Slaby <jslaby@suse.cz>,
Stefani Seibold <stefani@seibold.net>, Tejun Heo <tj@kernel.org>,
linux-kernel@vger.kernel.org, kernel-janitors@vger.kernel.org
Subject: Re: [bug] Fixing mutex_lock() under held spinlock
Date: Thu, 29 Jul 2010 13:34:56 +0000 [thread overview]
Message-ID: <201007291534.57188.arnd@arndb.de> (raw)
In-Reply-To: <20100729132223.GA19715@albatros>
On Thursday 29 July 2010, Vasiliy Kulikov wrote:
> I've found that cfi_cmdset and lpddr_cmds call mutex_lock() under held
> spinlock(). Maybe it was designed as a special locking scheme, so I
> don't try to fix it as I might create new complex locking problem.
No, it certainly looks like a bug and it seems to have been introduced by
http://linux.derkeiler.com/Mailing-Lists/Kernel/2010-03/msg02798.html
Back in March, Stefani wrote:
| I have analyzed this drivers and IMHO i don't think there will be used
| from irq or atomic contexts. There is no request interrupt and there are
| a lot msleep and add_wait_queues/schedule calls during holding the
| mutex, which are not very useful in a irq or atomic context. But i don't
| know the whole mtd stack.
It seems you have missed at least two places. It should be possible to
fix this by turning shared->lock into a mutex as well.
Arnd
WARNING: multiple messages have this Message-ID (diff)
From: Arnd Bergmann <arnd@arndb.de>
To: Vasiliy Kulikov <segooon@gmail.com>
Cc: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>,
David Woodhouse <David.Woodhouse@intel.com>,
Nicolas Pitre <nico@fluxnic.net>,
"Hans-Christian Egtvedt" <hans-christian.egtvedt@atmel.com>,
Jiri Slaby <jslaby@suse.cz>,
Stefani Seibold <stefani@seibold.net>, Tejun Heo <tj@kernel.org>,
linux-kernel@vger.kernel.org, kernel-janitors@vger.kernel.org
Subject: Re: [bug] Fixing mutex_lock() under held spinlock
Date: Thu, 29 Jul 2010 15:34:56 +0200 [thread overview]
Message-ID: <201007291534.57188.arnd@arndb.de> (raw)
In-Reply-To: <20100729132223.GA19715@albatros>
On Thursday 29 July 2010, Vasiliy Kulikov wrote:
> I've found that cfi_cmdset and lpddr_cmds call mutex_lock() under held
> spinlock(). Maybe it was designed as a special locking scheme, so I
> don't try to fix it as I might create new complex locking problem.
No, it certainly looks like a bug and it seems to have been introduced by
http://linux.derkeiler.com/Mailing-Lists/Kernel/2010-03/msg02798.html
Back in March, Stefani wrote:
| I have analyzed this drivers and IMHO i don't think there will be used
| from irq or atomic contexts. There is no request interrupt and there are
| a lot msleep and add_wait_queues/schedule calls during holding the
| mutex, which are not very useful in a irq or atomic context. But i don't
| know the whole mtd stack.
It seems you have missed at least two places. It should be possible to
fix this by turning shared->lock into a mutex as well.
Arnd
next prev parent reply other threads:[~2010-07-29 13:34 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-07-29 13:22 [bug] Fixing mutex_lock() under held spinlock Vasiliy Kulikov
2010-07-29 13:22 ` Vasiliy Kulikov
2010-07-29 13:34 ` Arnd Bergmann [this message]
2010-07-29 13:34 ` Arnd Bergmann
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