From: Andreas Mohr <andi@lisas.de>
To: Jiri Slaby <jirislaby@gmail.com>
Cc: Andreas Mohr <andi@lisas.de>,
Guennadi Liakhovetski <g.liakhovetski@gmx.de>,
Mauro Carvalho Chehab <mchehab@infradead.org>,
Luca Risolia <luca.risolia@studio.unibo.it>,
linux-media@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: V4L2 drivers: potentially dangerous and inefficient msecs_to_jiffies() calculation
Date: Mon, 14 Sep 2009 23:39:33 +0200 [thread overview]
Message-ID: <20090914213933.GA5468@rhlx01.hs-esslingen.de> (raw)
In-Reply-To: <4AAEB6F0.4080706@gmail.com>
Hi,
On Mon, Sep 14, 2009 at 11:34:40PM +0200, Jiri Slaby wrote:
> On 09/14/2009 11:07 PM, Andreas Mohr wrote:
> > ./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.
>
> In fact, msecs_to_jiffies(frame_timeout * 1000) makes much more sense.
Heh, right, even a bit better ;)
> > msecs_to_jiffies(1) is quite a bit too boldly assuming
> > that all of the msecs_to_jiffies(x) implementation branches
> > always round up.
>
> They do, don't they?
I'd hope so, but a slight risk remains, you never know,
especially with 4+ or so variants...
Andreas Mohr
next prev parent reply other threads:[~2009-09-14 21:39 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-09-14 21:07 V4L2 drivers: potentially dangerous and inefficient msecs_to_jiffies() calculation Andreas Mohr
2009-09-14 21:34 ` Jiri Slaby
2009-09-14 21:39 ` Andreas Mohr [this message]
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
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20090914213933.GA5468@rhlx01.hs-esslingen.de \
--to=andi@lisas.de \
--cc=g.liakhovetski@gmx.de \
--cc=jirislaby@gmail.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-media@vger.kernel.org \
--cc=luca.risolia@studio.unibo.it \
--cc=mchehab@infradead.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.