Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757409AbZINWN3 (ORCPT ); Mon, 14 Sep 2009 18:13:29 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756794AbZINWN2 (ORCPT ); Mon, 14 Sep 2009 18:13:28 -0400 Received: from rhlx01.hs-esslingen.de ([129.143.116.10]:58937 "EHLO rhlx01.hs-esslingen.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756200AbZINWN1 (ORCPT ); Mon, 14 Sep 2009 18:13:27 -0400 Date: Tue, 15 Sep 2009 00:13:29 +0200 From: Andreas Mohr To: Jiri Slaby Cc: Andreas Mohr , Guennadi Liakhovetski , Mauro Carvalho Chehab , Luca Risolia , linux-media@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: V4L2 drivers: potentially dangerous and inefficient msecs_to_jiffies() calculation Message-ID: <20090914221328.GA18867@rhlx01.hs-esslingen.de> References: <20090914210741.GA16799@rhlx01.hs-esslingen.de> <4AAEB6F0.4080706@gmail.com> <20090914213933.GA5468@rhlx01.hs-esslingen.de> <4AAEBABA.9060108@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4AAEBABA.9060108@gmail.com> 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 Content-Length: 3148 Lines: 72 On Mon, Sep 14, 2009 at 11:50:50PM +0200, Jiri Slaby wrote: > A potential problem here is rather that it may wait longer due to > returning 1 jiffie. It's then timeout * 1000 * 1. On 250HZ system it > makes a difference of multiple of 4. Don't think it's a real issue in > those drivers at all, but it's worth fixing. Care to post a patch? *sigh*. :) OK, last thing to be done this day. Generated via precise copy&paste of the change between drivers (which is a flashing warning that they likely contain too much c&p anyway), plus: for file in sn9c102/sn9c102_core.c et61x251/et61x251_core.c zc0301/zc0301_core.c; do diff -upN linux-2.6.31/drivers/media/video/"$file" linux-2.6.31.patched/drivers/media/video/"$file" >> /tmp/v4l2_drivers.diff; done Disclaimer: FULLY UNTESTED, make sure to guard your hen house, use as dog food. ChangeLog: Correct dangerous and inefficient msecs_to_jiffies() calculation in some V4L2 drivers Signed-off-by: Andreas Mohr --- linux-2.6.31/drivers/media/video/sn9c102/sn9c102_core.c 2009-09-10 00:13:59.000000000 +0200 +++ linux-2.6.31.patched/drivers/media/video/sn9c102/sn9c102_core.c 2009-09-14 23:58:27.000000000 +0200 @@ -1954,8 +1954,10 @@ sn9c102_read(struct file* filp, char __u (!list_empty(&cam->outqueue)) || (cam->state & DEV_DISCONNECTED) || (cam->state & DEV_MISCONFIGURED), - cam->module_param.frame_timeout * - 1000 * msecs_to_jiffies(1) ); + msecs_to_jiffies( + cam->module_param.frame_timeout * 1000 + ) + ); if (timeout < 0) { mutex_unlock(&cam->fileop_mutex); return timeout; --- linux-2.6.31/drivers/media/video/et61x251/et61x251_core.c 2009-09-10 00:13:59.000000000 +0200 +++ linux-2.6.31.patched/drivers/media/video/et61x251/et61x251_core.c 2009-09-14 23:58:54.000000000 +0200 @@ -1379,8 +1379,10 @@ et61x251_read(struct file* filp, char __ (!list_empty(&cam->outqueue)) || (cam->state & DEV_DISCONNECTED) || (cam->state & DEV_MISCONFIGURED), - cam->module_param.frame_timeout * - 1000 * msecs_to_jiffies(1) ); + msecs_to_jiffies( + cam->module_param.frame_timeout * 1000 + ) + ); if (timeout < 0) { mutex_unlock(&cam->fileop_mutex); return timeout; --- linux-2.6.31/drivers/media/video/zc0301/zc0301_core.c 2009-09-10 00:13:59.000000000 +0200 +++ linux-2.6.31.patched/drivers/media/video/zc0301/zc0301_core.c 2009-09-15 00:00:14.000000000 +0200 @@ -819,8 +819,10 @@ zc0301_read(struct file* filp, char __us (!list_empty(&cam->outqueue)) || (cam->state & DEV_DISCONNECTED) || (cam->state & DEV_MISCONFIGURED), - cam->module_param.frame_timeout * - 1000 * msecs_to_jiffies(1) ); + msecs_to_jiffies( + cam->module_param.frame_timeout * 1000 + ) + ); if (timeout < 0) { mutex_unlock(&cam->fileop_mutex); return timeout; -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/