From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757436AbdLUD5d (ORCPT ); Wed, 20 Dec 2017 22:57:33 -0500 Received: from userp2130.oracle.com ([156.151.31.86]:57714 "EHLO userp2130.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756542AbdLUD5a (ORCPT ); Wed, 20 Dec 2017 22:57:30 -0500 Subject: Re: [PATCH 5/7] blk-mq: remove REQ_ATOM_COMPLETE usages from blk-mq To: Tejun Heo , jbacik@fb.com Cc: jack@suse.cz, axboe@kernel.dk, clm@fb.com, kernel-team@fb.com, linux-kernel@vger.kernel.org, linux-btrfs@vger.kernel.org, peterz@infradead.org, Bart.VanAssche@wdc.com References: <20171216120726.517153-1-tj@kernel.org> <20171216120726.517153-6-tj@kernel.org> From: "jianchao.wang" Message-ID: <64dfa760-d433-1537-9bc6-b12cda3c9dc6@oracle.com> Date: Thu, 21 Dec 2017 11:56:49 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.5.0 MIME-Version: 1.0 In-Reply-To: <20171216120726.517153-6-tj@kernel.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Proofpoint-Virus-Version: vendor=nai engine=5900 definitions=8751 signatures=668651 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=0 malwarescore=0 phishscore=0 bulkscore=0 spamscore=0 mlxscore=0 mlxlogscore=923 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1711220000 definitions=main-1712210052 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi tejun On 12/16/2017 08:07 PM, Tejun Heo wrote: > After the recent updates to use generation number and state based > synchronization, blk-mq no longer depends on REQ_ATOM_COMPLETE except > to avoid firing the same timeout multiple times. > > Remove all REQ_ATOM_COMPLETE usages and use a new rq_flags flag > RQF_MQ_TIMEOUT_EXPIRED to avoid firing the same timeout multiple > times. This removes atomic bitops from hot paths too. > > v2: Removed blk_clear_rq_complete() from blk_mq_rq_timed_out(). > > v3: Added RQF_MQ_TIMEOUT_EXPIRED flag. > > Signed-off-by: Tejun Heo > Cc: "jianchao.wang" > --- > block/blk-mq.c | 18 ++++++++---------- > block/blk-timeout.c | 1 + > include/linux/blkdev.h | 2 ++ > 3 files changed, 11 insertions(+), 10 deletions(-) > > diff --git a/block/blk-mq.c b/block/blk-mq.c > index 88baa82..47e722b 100644 > --- a/block/blk-mq.c > +++ b/block/blk-mq.c > @@ -607,14 +607,12 @@ void blk_mq_complete_request(struct request *rq) > */ > if (!(hctx->flags & BLK_MQ_F_BLOCKING)) { > rcu_read_lock(); > - if (blk_mq_rq_aborted_gstate(rq) != rq->gstate && > - !blk_mark_rq_complete(rq)) > + if (blk_mq_rq_aborted_gstate(rq) != rq->gstate) > __blk_mq_complete_request(rq); > rcu_read_unlock(); > } else { > srcu_idx = srcu_read_lock(hctx->queue_rq_srcu); > - if (blk_mq_rq_aborted_gstate(rq) != rq->gstate && > - !blk_mark_rq_complete(rq)) > + if (blk_mq_rq_aborted_gstate(rq) != rq->gstate) > __blk_mq_complete_request(rq); > srcu_read_unlock(hctx->queue_rq_srcu, srcu_idx); > } It's worrying that even though the blk_mark_rq_complete() here is intended to synchronize with timeout path, but it indeed give the blk_mq_complete_request() the capability to exclude with itself. Maybe this capability should be reserved. Thanks Jianchao