From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261387AbUKIFy6 (ORCPT ); Tue, 9 Nov 2004 00:54:58 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261420AbUKIFxJ (ORCPT ); Tue, 9 Nov 2004 00:53:09 -0500 Received: from mail.kroah.org ([69.55.234.183]:4767 "EHLO perch.kroah.org") by vger.kernel.org with ESMTP id S261386AbUKIFZC convert rfc822-to-8bit (ORCPT ); Tue, 9 Nov 2004 00:25:02 -0500 Subject: Re: [PATCH] I2C update for 2.6.10-rc1 In-Reply-To: <10999778541107@kroah.com> X-Mailer: gregkh_patchbomb Date: Mon, 8 Nov 2004 21:24:14 -0800 Message-Id: <10999778542218@kroah.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII To: linux-kernel@vger.kernel.org, sensors@stimpy.netroedge.com Content-Transfer-Encoding: 7BIT From: Greg KH Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org ChangeSet 1.2014.1.2, 2004/10/22 12:52:13-07:00, ebs@ebshome.net [PATCH] I2C: fix recently introduced race in IBM PPC4xx I2C driver 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. Signed-off-by: Eugene Surovegin Signed-off-by: Greg Kroah-Hartman drivers/i2c/busses/i2c-ibm_iic.c | 16 +++++----------- 1 files changed, 5 insertions(+), 11 deletions(-) diff -Nru a/drivers/i2c/busses/i2c-ibm_iic.c b/drivers/i2c/busses/i2c-ibm_iic.c --- a/drivers/i2c/busses/i2c-ibm_iic.c 2004-11-08 18:56:20 -08:00 +++ b/drivers/i2c/busses/i2c-ibm_iic.c 2004-11-08 18:56:20 -08:00 @@ -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; }