From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261715AbVFPDrR (ORCPT ); Wed, 15 Jun 2005 23:47:17 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261719AbVFPDrR (ORCPT ); Wed, 15 Jun 2005 23:47:17 -0400 Received: from wproxy.gmail.com ([64.233.184.207]:924 "EHLO wproxy.gmail.com") by vger.kernel.org with ESMTP id S261715AbVFPDrN (ORCPT ); Wed, 15 Jun 2005 23:47:13 -0400 DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=beta; d=gmail.com; h=received:date:from:to:subject:message-id:mime-version:content-type:content-disposition:user-agent; b=jxT1b7dVhQZvsuFeTUnDzdj+/ZCvqM4Ni8zo8WFWroNrZrI2I0X/iJ4JEnET7kt8Qs/L/lrKxv1YJb2FSKyVK+BFvtAiOy9PThnzkVQSvCA752sM0mgPG+IwTCBJRdggzXzoee78c+pvCdlVGPbPlbS2K4A8tQ8gJtskNuBSf3g= Date: Thu, 16 Jun 2005 12:47:06 +0900 From: Tejun Heo To: axboe@suse.de, akpm@osdl.org, linux-kernel@vger.kernel.org Subject: [PATCH linux-2.6.12-rc6-mm1] blk: elevator unplug thresh hanlding fix Message-ID: <20050616034705.GA29048@htj.dyndns.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.5.9i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Hello, Jens. Hello, Andrew. This patch fixes q->unplug_thresh condition check in __elv_add_request(). rq.count[READ] + rq.count[WRITE] can increase more than one if another thread has allocated a request after the current request is allocated or in_flight could have changed resulting in larger-than-one change of nrq, thus breaking the threshold mechanism. Signed-off-by: Tejun Heo Index: blk-fixes/drivers/block/elevator.c =================================================================== --- blk-fixes.orig/drivers/block/elevator.c 2005-06-16 12:16:59.000000000 +0900 +++ blk-fixes/drivers/block/elevator.c 2005-06-16 12:17:03.000000000 +0900 @@ -352,7 +352,7 @@ void __elv_add_request(request_queue_t * int nrq = q->rq.count[READ] + q->rq.count[WRITE] - q->in_flight; - if (nrq == q->unplug_thresh) + if (nrq >= q->unplug_thresh) __generic_unplug_device(q); } } else