From mboxrd@z Thu Jan 1 00:00:00 1970 From: Kamezawa Hiroyuki Subject: Re: [PATCH v4 08/14] res_counter: return amount of charges after res_counter_uncharge Date: Tue, 16 Oct 2012 17:20:34 +0900 Message-ID: <507D18D2.5020707@jp.fujitsu.com> References: <1349690780-15988-1-git-send-email-glommer@parallels.com> <1349690780-15988-9-git-send-email-glommer@parallels.com> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1349690780-15988-9-git-send-email-glommer-bzQdu9zFT3WakBO8gow8eQ@public.gmane.org> Sender: cgroups-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-ID: Content-Type: text/plain; charset="us-ascii" To: Glauber Costa Cc: linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org, Andrew Morton , Mel Gorman , Suleiman Souhlal , Tejun Heo , cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Michal Hocko , Johannes Weiner , Greg Thelen , devel-GEFAQzZX7r8dnm+yROfE0A@public.gmane.org, Frederic Weisbecker (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