From patchwork Tue Jun 23 15:04:39 2009 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jesper Dangaard Brouer X-Patchwork-Id: 29075 X-Patchwork-Delegate: davem@davemloft.net Return-Path: X-Original-To: patchwork-incoming@bilbo.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from ozlabs.org (ozlabs.org [203.10.76.45]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client CN "mx.ozlabs.org", Issuer "CA Cert Signing Authority" (verified OK)) by bilbo.ozlabs.org (Postfix) with ESMTPS id 7E97DB7095 for ; Wed, 24 Jun 2009 01:30:45 +1000 (EST) Received: by ozlabs.org (Postfix) id 73036DDDF4; Wed, 24 Jun 2009 01:30:45 +1000 (EST) Delivered-To: patchwork-incoming@ozlabs.org Received: from vger.kernel.org (vger.kernel.org [209.132.176.167]) by ozlabs.org (Postfix) with ESMTP id EF478DDDF0 for ; Wed, 24 Jun 2009 01:30:44 +1000 (EST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759590AbZFWPa2 (ORCPT ); Tue, 23 Jun 2009 11:30:28 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754496AbZFWP3z (ORCPT ); Tue, 23 Jun 2009 11:29:55 -0400 Received: from lanfw001a.cxnet.dk ([87.72.215.196]:49574 "EHLO lanfw001a.cxnet.dk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756737AbZFWP3u (ORCPT ); Tue, 23 Jun 2009 11:29:50 -0400 Received: from hotlava.cxnet.dk (unknown [172.31.4.152]) by lanfw001a.cxnet.dk (Postfix) with ESMTP id 94A4C16385E; Tue, 23 Jun 2009 17:04:39 +0200 (CEST) Received: from [127.0.0.1] (localhost [127.0.0.1]) by hotlava.cxnet.dk (Postfix) with ESMTP id 858A045C068; Tue, 23 Jun 2009 17:04:39 +0200 (CEST) From: Jesper Dangaard Brouer Subject: [PATCH 09/10] cfq-iosched: Uses its own open-coded rcu_barrier. To: "David S. Miller" Cc: Jesper Dangaard Brouer , "Paul E. McKenney" , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, dougthompson@xmission.com, bluesmoke-devel@lists.sourceforge.net, axboe@kernel.dk, "Patrick McHardy" , christine.caulfield@googlemail.com, Trond.Myklebust@netapp.com, linux-wireless@vger.kernel.org, johannes@sipsolutions.net, yoshfuji@linux-ipv6.org, shemminger@linux-foundation.org, linux-nfs@vger.kernel.org, bfields@fieldses.org, neilb@suse.de, linux-ext4@vger.kernel.org, tytso@mit.edu, adilger@sun.com, netfilter-devel@vger.kernel.org Date: Tue, 23 Jun 2009 17:04:39 +0200 Message-ID: <20090623150439.22490.14657.stgit@localhost> In-Reply-To: <20090623150330.22490.87327.stgit@localhost> References: <20090623150330.22490.87327.stgit@localhost> User-Agent: StGIT/0.14.2 MIME-Version: 1.0 Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org This module cfq-iosched, has discovered the value of waiting for call_rcu() completion, but its has its own open-coded implementation of rcu_barrier(), which I don't think is 'strong' enough. This patch only leaves a comment for the maintainers to consider. Signed-off-by: Jesper Dangaard Brouer --- block/cfq-iosched.c | 6 ++++++ 1 files changed, 6 insertions(+), 0 deletions(-) -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c index 833ec18..c15555b 100644 --- a/block/cfq-iosched.c +++ b/block/cfq-iosched.c @@ -2657,6 +2657,12 @@ static void __exit cfq_exit(void) /* * this also protects us from entering cfq_slab_kill() with * pending RCU callbacks + * + * hawk@comx.dk 2009-06-18: Maintainer please consider using + * rcu_barrier() instead of this open-coded wait for + * completion implementation. I think it provides a better + * guarantee that all CPUs are finished, although + * elv_ioc_count_read() do consider all CPUs. */ if (elv_ioc_count_read(ioc_count)) wait_for_completion(&all_gone);