Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759673Ab0LNQ4i (ORCPT ); Tue, 14 Dec 2010 11:56:38 -0500 Received: from mx1.redhat.com ([209.132.183.28]:22334 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758913Ab0LNQ4h (ORCPT ); Tue, 14 Dec 2010 11:56:37 -0500 From: Jeff Moyer To: Gui Jianfeng Cc: Jens Axboe , Vivek Goyal , linux kernel mailing list Subject: Re: [PATCH] cfq-iosched: don't check cfqg in choose_service_tree() References: <4D070F7C.3060503@cn.fujitsu.com> X-PGP-KeyID: 1F78E1B4 X-PGP-CertKey: F6FE 280D 8293 F72C 65FD 5A58 1FF8 A7CA 1F78 E1B4 X-PCLoadLetter: What the f**k does that mean? Date: Tue, 14 Dec 2010 11:56:29 -0500 In-Reply-To: <4D070F7C.3060503@cn.fujitsu.com> (Gui Jianfeng's message of "Tue, 14 Dec 2010 14:32:28 +0800") Message-ID: User-Agent: Gnus/5.110011 (No Gnus v0.11) Emacs/23.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 735 Lines: 16 Gui Jianfeng writes: > When cfq_choose_cfqg() is called in select_queue(), there must be at least one > backlogged CFQ queue waiting for dispatching, hence there must be at least one > backlogged CFQ group on service tree. So we never call choose_service_tree() > with cfqg == NULL. Further, if cfqg was NULL, cfq_choose_cfqg would have dereferenced a NULL pointer and we wouldn't even get to choose_service_tree. Reviewed-by: Jeff Moyer -- 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/