From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933812AbZINVHp (ORCPT ); Mon, 14 Sep 2009 17:07:45 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S933711AbZINVHo (ORCPT ); Mon, 14 Sep 2009 17:07:44 -0400 Received: from rhlx01.hs-esslingen.de ([129.143.116.10]:50042 "EHLO rhlx01.hs-esslingen.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933696AbZINVHj (ORCPT ); Mon, 14 Sep 2009 17:07:39 -0400 Date: Mon, 14 Sep 2009 23:07:41 +0200 From: Andreas Mohr To: Guennadi Liakhovetski , Mauro Carvalho Chehab Cc: Luca Risolia , linux-media@vger.kernel.org, linux-kernel@vger.kernel.org Subject: V4L2 drivers: potentially dangerous and inefficient msecs_to_jiffies() calculation Message-ID: <20090914210741.GA16799@rhlx01.hs-esslingen.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline X-Priority: none User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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