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Date: Tue, 17 Jul 2012 22:15:57 +0200
From: Nikolaus Schulz <schulz@macnetix.de>
To: Mauro Carvalho Chehab <mchehab@infradead.org>
CC: Jonathan Nieder <jrnieder@gmail.com>,
	Oliver Endriss <o.endriss@gmx.de>,
	Andreas Oberritter <obi@linuxtv.org>,
	<linux-media@vger.kernel.org>
Subject: Re: [PATCH] dvb: push down ioctl lock in dvb_usercopy
Message-ID: <20120717201557.GA18369@pcewns01.macnetix.de>
References: <1340300655-17696-1-git-send-email-schulz@macnetix.de>
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Hi!

I don't want to press or annoy anybody, but may I ask what's the status
of this patch[1]?

On Thu, Jun 21, 2012 at 07:44:15PM +0200, schulz@macnetix.de wrote:
> Since most dvb ioctls wrap their real work with dvb_usercopy, the static mutex
> used in dvb_usercopy effectively is a global lock for dvb ioctls.
> Unfortunately, frontend ioctls can be blocked by the frontend thread for
> several seconds; this leads to unacceptable lock contention.  Mitigate that by
> pushing the mutex from dvb_usercopy down to the individual, device specific
> ioctls.

On our systems, this patch has a great effect in terms of scalability
when operating multiple DVB tuners.

Is it going to be considered?

Thanks,
Nikolaus

[1] http://patchwork.linuxtv.org/patch/12989/