Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754731Ab2JVPbf (ORCPT ); Mon, 22 Oct 2012 11:31:35 -0400 Received: from mx1.redhat.com ([209.132.183.28]:37571 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751211Ab2JVPbe (ORCPT ); Mon, 22 Oct 2012 11:31:34 -0400 Date: Mon, 22 Oct 2012 11:31:27 -0400 From: Vivek Goyal To: "Jun'ichi Nomura" Cc: "linux-kernel@vger.kernel.org" , Tejun Heo , Jens Axboe Subject: Re: [PATCH] blkcg: stop iteration early if root_rl is the only request list Message-ID: <20121022153127.GB3401@redhat.com> References: <50750367.2070508@ce.jp.nec.com> <20121010155929.GA18733@redhat.com> <50762182.5090806@ce.jp.nec.com> <20121016232040.GH16166@google.com> <507DF58E.8060804@ce.jp.nec.com> <20121017134704.GB31663@redhat.com> <507F6FE2.3030303@ce.jp.nec.com> <20121018133149.GA18147@redhat.com> <20121018212053.GK13370@google.com> <50849E39.2040609@ce.jp.nec.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <50849E39.2040609@ce.jp.nec.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1473 Lines: 42 On Mon, Oct 22, 2012 at 10:15:37AM +0900, Jun'ichi Nomura wrote: > __blk_queue_next_rl() finds next request list based on blkg_list > while skipping root_blkg in the list. > OTOH, root_rl is special as it may exist even without root_blkg. > > Though the later part of the function handles such a case correctly, > exiting early is good for readability of the code. > Thanks for the patch Junichi. This one looks good to me. Acked-by: Vivek Goyal Vivek > Signed-off-by: Jun'ichi Nomura > Cc: Vivek Goyal > Cc: Tejun Heo > Cc: Jens Axboe > --- > block/blk-cgroup.c | 3 +++ > 1 files changed, 3 insertions(+), 0 deletions(-) > > diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c > index 54f35d1..a31e678 100644 > --- a/block/blk-cgroup.c > +++ b/block/blk-cgroup.c > @@ -333,6 +333,9 @@ struct request_list *__blk_queue_next_rl(struct request_list *rl, > */ > if (rl == &q->root_rl) { > ent = &q->blkg_list; > + /* There are no more block groups, hence no request lists */ > + if (list_empty(ent)) > + return NULL; > } else { > blkg = container_of(rl, struct blkcg_gq, rl); > ent = &blkg->q_node; -- 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/