From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 986A8C43381 for ; Mon, 18 Mar 2019 03:30:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6DA1420857 for ; Mon, 18 Mar 2019 03:30:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727711AbfCRDaR (ORCPT ); Sun, 17 Mar 2019 23:30:17 -0400 Received: from mx1.redhat.com ([209.132.183.28]:50082 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726828AbfCRDaQ (ORCPT ); Sun, 17 Mar 2019 23:30:16 -0400 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 958BA3086200; Mon, 18 Mar 2019 03:30:16 +0000 (UTC) Received: from localhost (ovpn-8-24.pek2.redhat.com [10.72.8.24]) by smtp.corp.redhat.com (Postfix) with ESMTP id 7A32F5C28F; Mon, 18 Mar 2019 03:30:05 +0000 (UTC) From: Ming Lei To: Jens Axboe Cc: linux-block@vger.kernel.org, Ming Lei , Christoph Hellwig , linux-nvme@lists.infradead.org Subject: [PATCH 1/2] blk-mq: introduce blk_mq_complete_request_sync() Date: Mon, 18 Mar 2019 11:29:49 +0800 Message-Id: <20190318032950.17770-2-ming.lei@redhat.com> In-Reply-To: <20190318032950.17770-1-ming.lei@redhat.com> References: <20190318032950.17770-1-ming.lei@redhat.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.42]); Mon, 18 Mar 2019 03:30:16 +0000 (UTC) Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org In NVMe's error handler, follows the typical steps for tearing down hardware: 1) stop blk_mq hw queues 2) stop the real hw queues 3) cancel in-flight requests via blk_mq_tagset_busy_iter(tags, cancel_request, ...) cancel_request(): mark the request as abort blk_mq_complete_request(req); 4) destroy real hw queues However, there may be race between #3 and #4, because blk_mq_complete_request() actually completes the request asynchronously. This patch introduces blk_mq_complete_request_sync() for fixing the above race. Cc: Christoph Hellwig Cc: linux-nvme@lists.infradead.org Signed-off-by: Ming Lei --- block/blk-mq.c | 20 ++++++++++++++++---- include/linux/blk-mq.h | 1 + 2 files changed, 17 insertions(+), 4 deletions(-) diff --git a/block/blk-mq.c b/block/blk-mq.c index a9c181603cbd..8f925ac0b26d 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -569,7 +569,7 @@ static void __blk_mq_complete_request_remote(void *data) q->mq_ops->complete(rq); } -static void __blk_mq_complete_request(struct request *rq) +static void __blk_mq_complete_request(struct request *rq, bool sync) { struct blk_mq_ctx *ctx = rq->mq_ctx; struct request_queue *q = rq->q; @@ -586,7 +586,7 @@ static void __blk_mq_complete_request(struct request *rq) * So complete IO reqeust in softirq context in case of single queue * for not degrading IO performance by irqsoff latency. */ - if (q->nr_hw_queues == 1) { + if (q->nr_hw_queues == 1 && !sync) { __blk_complete_request(rq); return; } @@ -594,8 +594,11 @@ static void __blk_mq_complete_request(struct request *rq) /* * For a polled request, always complete locallly, it's pointless * to redirect the completion. + * + * If driver requires to complete the request synchronously, + * complete it locally, and it is usually done in error handler. */ - if ((rq->cmd_flags & REQ_HIPRI) || + if ((rq->cmd_flags & REQ_HIPRI) || sync || !test_bit(QUEUE_FLAG_SAME_COMP, &q->queue_flags)) { q->mq_ops->complete(rq); return; @@ -648,11 +651,20 @@ bool blk_mq_complete_request(struct request *rq) { if (unlikely(blk_should_fake_timeout(rq->q))) return false; - __blk_mq_complete_request(rq); + __blk_mq_complete_request(rq, false); return true; } EXPORT_SYMBOL(blk_mq_complete_request); +bool blk_mq_complete_request_sync(struct request *rq) +{ + if (unlikely(blk_should_fake_timeout(rq->q))) + return false; + __blk_mq_complete_request(rq, true); + return true; +} +EXPORT_SYMBOL(blk_mq_complete_request_sync); + int blk_mq_request_started(struct request *rq) { return blk_mq_rq_state(rq) != MQ_RQ_IDLE; diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h index b0c814bcc7e3..6a514e5136f4 100644 --- a/include/linux/blk-mq.h +++ b/include/linux/blk-mq.h @@ -305,6 +305,7 @@ void blk_mq_add_to_requeue_list(struct request *rq, bool at_head, void blk_mq_kick_requeue_list(struct request_queue *q); void blk_mq_delay_kick_requeue_list(struct request_queue *q, unsigned long msecs); bool blk_mq_complete_request(struct request *rq); +bool blk_mq_complete_request_sync(struct request *rq); bool blk_mq_bio_list_merge(struct request_queue *q, struct list_head *list, struct bio *bio); bool blk_mq_queue_stopped(struct request_queue *q); -- 2.9.5