From: Evgeniy Polyakov <zbr@ioremap.net>
To: NeilBrown <neilb@suse.de>
Cc: linux-kernel@vger.kernel.org,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Subject: Re: [PATCH] w1: Introduce a slave mutex for serializing IO.
Date: Wed, 2 May 2012 01:39:58 +0400 [thread overview]
Message-ID: <20120501213958.GA15560@ioremap.net> (raw)
In-Reply-To: <20120425124914.3187a794@notabene.brown>
On Wed, Apr 25, 2012 at 12:49:14PM +1000, NeilBrown (neilb@suse.de) wrote:
> w1 devices need a mutex to serial IO.
> Most use master->mutex.
>
> However that is used for other purposes and they can conflict.
>
> In particular master->mutex is held while w1_attach_slave_device is
> called.
>
> For bq27000, this registers a 'powersupply' device which tries to
> read the current status. The attempt to read will cause a deadlock on
> master->mutex.
>
> So create a new per-slave mutex and use that for serializing IO for
> bq27000.
How will this protect against master doing search for example?
It performs a number of read/write operations which are not allowed to
be interrupted by outside read.
--
Evgeniy Polyakov
next prev parent reply other threads:[~2012-05-01 21:40 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-04-25 2:49 [PATCH] w1: Introduce a slave mutex for serializing IO NeilBrown
2012-05-01 21:39 ` Evgeniy Polyakov [this message]
2012-05-02 6:26 ` NeilBrown
2012-05-03 17:58 ` Evgeniy Polyakov
2012-05-03 21:08 ` NeilBrown
2012-05-03 21:27 ` Evgeniy Polyakov
2012-05-09 1:43 ` NeilBrown
2012-05-15 1:26 ` Evgeniy Polyakov
2012-05-18 6:05 ` NeilBrown
2012-06-10 20:58 ` Evgeniy Polyakov
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