From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261230AbTENIHD (ORCPT ); Wed, 14 May 2003 04:07:03 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261233AbTENIHD (ORCPT ); Wed, 14 May 2003 04:07:03 -0400 Received: from e35.co.us.ibm.com ([32.97.110.133]:1251 "EHLO e35.co.us.ibm.com") by vger.kernel.org with ESMTP id S261230AbTENIGy (ORCPT ); Wed, 14 May 2003 04:06:54 -0400 Date: Wed, 14 May 2003 13:38:43 +0530 From: Bharata B Rao To: Jens Axboe Cc: "Martin J. Bligh" , Adrian Bunk , linux-kernel , Suparna Bhattacharya Subject: Re: 2.5.69-mjb1: undefined reference to `blk_queue_empty' Message-ID: <20030514133843.H31823@in.ibm.com> Reply-To: bharata@in.ibm.com References: <9380000.1052624649@[10.10.2.4]> <20030512205139.GT1107@fs.tum.de> <20570000.1052797864@[10.10.2.4]> <20030513124807.A31823@in.ibm.com> <25840000.1052834304@[10.10.2.4]> <20030513181155.GL17033@suse.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.2.5.1i In-Reply-To: <20030513181155.GL17033@suse.de>; from axboe@suse.de on Tue, May 13, 2003 at 08:11:55PM +0200 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Tue, May 13, 2003 at 08:11:55PM +0200, Jens Axboe wrote: > > > > > > /* For now we assume we have the device to ourselves */ > > > /* Just a quick sanity check */ > > > - if (!blk_queue_empty(bdev_get_queue(dump_bdev->bdev))) { > > > + if (elv_next_request(bdev_get_queue(dump_bdev->bdev))) { > > > /* i/o in flight - safer to quit */ > > > return -EBUSY; > > > } > > this looks horribly racy (of the io scheduler internals corrupting > kind), I don't see you holding the queue lock here. some io schedulers > do non-significant amount of work inside they next_request functions, > moving from back-end lists to dispatch queue. > Jens, All we want to do here is to check if there are requests in the queue. Hence thinking of using elv_queue_empty(). Do you think we still need to acquire queue lock for this ? This code will be run when we have stopped everything else in other cpus by putting them into spin. --- 2569+mjb1/drivers/dump/dump_blockdev.c.orig Wed May 14 13:23:36 2003 +++ 2569+mjb1/drivers/dump/dump_blockdev.c Wed May 14 13:24:58 2003 @@ -258,10 +258,11 @@ dump_block_silence(struct dump_dev *dev) { struct dump_blockdev *dump_bdev = DUMP_BDEV(dev); + struct request_queue *q = bdev_get_queue(dump_bdev->bdev); /* For now we assume we have the device to ourselves */ /* Just a quick sanity check */ - if (!blk_queue_empty(bdev_get_queue(dump_bdev->bdev))) { + if (!elv_queue_empty(q)) { /* i/o in flight - safer to quit */ return -EBUSY; } Regards, Bharata.