Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932298Ab0FYSzG (ORCPT ); Fri, 25 Jun 2010 14:55:06 -0400 Received: from 0122700014.0.fullrate.dk ([95.166.99.235]:53913 "EHLO kernel.dk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756734Ab0FYSzE (ORCPT ); Fri, 25 Jun 2010 14:55:04 -0400 Message-ID: <4C24FB84.5050408@kernel.dk> Date: Fri, 25 Jun 2010 20:55:00 +0200 From: Jens Axboe MIME-Version: 1.0 To: Jeff Moyer CC: Vivek Goyal , linux-kernel@vger.kernel.org, linux-ext4@vger.kernel.org Subject: Re: [PATCH 1/3] block: Implement a blk_yield function to voluntarily give up the I/O scheduler. References: <1277242502-9047-1-git-send-email-jmoyer@redhat.com> <1277242502-9047-2-git-send-email-jmoyer@redhat.com> <20100624004622.GA3297@redhat.com> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 660 Lines: 20 On 25/06/10 18.51, Jeff Moyer wrote: >>> + cfq_log_cfqq(cfqd, cfqq, "yielding queue to %d", tsk->pid); >>> + cfqq->yield_to = new_cic; >> >> We are stashing away a pointer to cic without taking reference? > > There is no reference counting on the cic. Not on the cic itself, but on the io context it belongs to. So you need to grab a reference to that, if you are stowing a reference to the cic. -- Jens Axboe -- 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/