From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S270144AbUJTGgb (ORCPT ); Wed, 20 Oct 2004 02:36:31 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S270163AbUJTGcL (ORCPT ); Wed, 20 Oct 2004 02:32:11 -0400 Received: from gate.ebshome.net ([64.81.67.12]:9703 "EHLO gate.ebshome.net") by vger.kernel.org with ESMTP id S268069AbUJTG0j (ORCPT ); Wed, 20 Oct 2004 02:26:39 -0400 Date: Tue, 19 Oct 2004 23:26:33 -0700 From: Eugene Surovegin To: Greg KH Cc: linux-kernel@vger.kernel.org, sensors@stimpy.netroedge.com, Nishanth Aravamudan Subject: [PATCH] fix recently introduced race in IBM PPC4xx I2C driver Message-ID: <20041020062633.GA16580@gate.ebshome.net> Mail-Followup-To: Greg KH , linux-kernel@vger.kernel.org, sensors@stimpy.netroedge.com, Nishanth Aravamudan References: <10982315061975@kroah.com> <1098231506495@kroah.com> <20041020052108.GA14871@gate.ebshome.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20041020052108.GA14871@gate.ebshome.net> X-ICQ-UIN: 1193073 X-Operating-System: Linux i686 X-PGP-Key: http://www.ebshome.net/pubkey.asc User-Agent: Mutt/1.5.5.1i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Oct 19, 2004 at 10:21:08PM -0700, Eugene Surovegin wrote: [snip] > It looks like this change added race I tried to avoid here. > > This code is modeled after __wait_event_interruptible_timeout, where > "prepare_to_wait" is done _before_ checking completion status. This > change breaks this, e.g. if IRQ happens right after we check iic->sts, > but before calling msleep_interruptible(). In this case we'll sleep > much more than required (seconds instead of microseconds) > > Greg, if my analysis is correct, please rollback this change. > > Nishanth, I'd be nice if you CC'ed me with this patch, my e-mail is at > the top of that source file. Oh, well. I should have used wait_event_interruptible_timeout when I ported this driver to 2.6. This patch fixes recently introduced race and also cleans ups some 2.4-ism. Please, apply. Signed-off-by: Eugene Surovegin ===== drivers/i2c/busses/i2c-ibm_iic.c 1.12 vs edited ===== --- 1.12/drivers/i2c/busses/i2c-ibm_iic.c 2004-10-14 11:30:08 -07:00 +++ edited/drivers/i2c/busses/i2c-ibm_iic.c 2004-10-19 23:18:16 -07:00 @@ -412,18 +412,12 @@ if (dev->irq >= 0){ /* Interrupt mode */ - wait_queue_t wait; - init_waitqueue_entry(&wait, current); - - add_wait_queue(&dev->wq, &wait); - if (in_8(&iic->sts) & STS_PT) - msleep_interruptible(dev->adap.timeout * 1000); - remove_wait_queue(&dev->wq, &wait); - - if (unlikely(signal_pending(current))){ + ret = wait_event_interruptible_timeout(dev->wq, + !(in_8(&iic->sts) & STS_PT), dev->adap.timeout * HZ); + + if (unlikely(ret < 0)) DBG("%d: wait interrupted\n", dev->idx); - ret = -ERESTARTSYS; - } else if (unlikely(in_8(&iic->sts) & STS_PT)){ + else if (unlikely(in_8(&iic->sts) & STS_PT)){ DBG("%d: wait timeout\n", dev->idx); ret = -ETIMEDOUT; }