Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754257Ab2JPIVY (ORCPT ); Tue, 16 Oct 2012 04:21:24 -0400 Received: from fgwmail5.fujitsu.co.jp ([192.51.44.35]:37196 "EHLO fgwmail5.fujitsu.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752356Ab2JPIVV (ORCPT ); Tue, 16 Oct 2012 04:21:21 -0400 X-SecurityPolicyCheck: OK by SHieldMailChecker v1.8.4 Message-ID: <507D18D2.5020707@jp.fujitsu.com> Date: Tue, 16 Oct 2012 17:20:34 +0900 From: Kamezawa Hiroyuki User-Agent: Mozilla/5.0 (Windows NT 6.1; rv:16.0) Gecko/20121010 Thunderbird/16.0.1 MIME-Version: 1.0 To: Glauber Costa CC: linux-kernel@vger.kernel.org, linux-mm@kvack.org, Andrew Morton , Mel Gorman , Suleiman Souhlal , Tejun Heo , cgroups@vger.kernel.org, Michal Hocko , Johannes Weiner , Greg Thelen , devel@openvz.org, Frederic Weisbecker Subject: Re: [PATCH v4 08/14] res_counter: return amount of charges after res_counter_uncharge References: <1349690780-15988-1-git-send-email-glommer@parallels.com> <1349690780-15988-9-git-send-email-glommer@parallels.com> In-Reply-To: <1349690780-15988-9-git-send-email-glommer@parallels.com> Content-Type: text/plain; charset=ISO-2022-JP Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1428 Lines: 33 (2012/10/08 19:06), Glauber Costa wrote: > It is useful to know how many charges are still left after a call to > res_counter_uncharge. While it is possible to issue a res_counter_read > after uncharge, this can be racy. > > If we need, for instance, to take some action when the counters drop > down to 0, only one of the callers should see it. This is the same > semantics as the atomic variables in the kernel. > > Since the current return value is void, we don't need to worry about > anything breaking due to this change: nobody relied on that, and only > users appearing from now on will be checking this value. > > Signed-off-by: Glauber Costa > CC: Michal Hocko > CC: Johannes Weiner > CC: Suleiman Souhlal > CC: Kamezawa Hiroyuki > --- > Documentation/cgroups/resource_counter.txt | 7 ++++--- > include/linux/res_counter.h | 12 +++++++----- > kernel/res_counter.c | 20 +++++++++++++------- > 3 files changed, 24 insertions(+), 15 deletions(-) Acked-by: KAMEZAWA Hiroyuki -- 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/