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From: Andreas Mohr <andi@lisas.de>
To: Guennadi Liakhovetski <g.liakhovetski@gmx.de>,
	Mauro Carvalho Chehab <mchehab@infradead.org>
Cc: Luca Risolia <luca.risolia@studio.unibo.it>,
	linux-media@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: V4L2 drivers: potentially dangerous and inefficient msecs_to_jiffies() calculation
Date: Mon, 14 Sep 2009 23:07:41 +0200	[thread overview]
Message-ID: <20090914210741.GA16799@rhlx01.hs-esslingen.de> (raw)

Hi all,

./drivers/media/video/sn9c102/sn9c102_core.c
,
./drivers/media/video/et61x251/et61x251_core.c
and
./drivers/media/video/zc0301/zc0301_core.c
do
                            cam->module_param.frame_timeout *
                            1000 * msecs_to_jiffies(1) );
multiple times each.
What they should do instead is
frame_timeout * msecs_to_jiffies(1000), I'd think.
msecs_to_jiffies(1) is quite a bit too boldly assuming
that all of the msecs_to_jiffies(x) implementation branches
always round up.

Not to mention that the current implementation needs one additional
multiplication operation as opposed to constant-aggregating it into the
msecs_to_jiffies() argument and thus nicely evaporating it into nirvana.

HTH,

Andreas Mohr

             reply	other threads:[~2009-09-14 21:07 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-09-14 21:07 Andreas Mohr [this message]
2009-09-14 21:34 ` Jiri Slaby
2009-09-14 21:39   ` Andreas Mohr
2009-09-14 21:50     ` Jiri Slaby
2009-09-14 22:13       ` Andreas Mohr
2009-09-14 21:47 ` Trent Piepho
2009-09-15 19:14 ` Marcin Slusarz
2009-09-15 19:21   ` Andreas Mohr
2009-09-19 10:08     ` Andreas Mohr

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