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bh=WXlA6iqVOZ8HZCskOLfpH3kSJ9rX1tyyGRi5s9Wu9iw=; b=PaYEkpR5BCFFYglnIkPPaF4slxor62hplHouTsyq3PEUg2Qb0T5/0rJiaMSIu9RDEeYWHO 6VMbEm9wVsaGrx7W8AzzLEQHbrcycxHlR4NuE7fiOrZY9pssN4TbAPgWhALU0MQQLhk0co 2EUkjvgyipgtrDEg9+/VcAD9/EGctyU= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-463-g_-QqIjAO2yX27Jj5FiJ3Q-1; Wed, 20 May 2020 07:57:15 -0400 X-MC-Unique: g_-QqIjAO2yX27Jj5FiJ3Q-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 5E5AA461; Wed, 20 May 2020 11:57:13 +0000 (UTC) Received: from localhost (ovpn-12-81.pek2.redhat.com [10.72.12.81]) by smtp.corp.redhat.com (Postfix) with ESMTP id 20EB1579A5; Wed, 20 May 2020 11:57:08 +0000 (UTC) From: Ming Lei To: Jens Axboe , linux-block@vger.kernel.org, linux-nvme@lists.infradead.org, Christoph Hellwig Subject: [PATCH 1/3] blk-mq: add API of blk_mq_queue_frozen Date: Wed, 20 May 2020 19:56:53 +0800 Message-Id: <20200520115655.729705-2-ming.lei@redhat.com> In-Reply-To: <20200520115655.729705-1-ming.lei@redhat.com> References: <20200520115655.729705-1-ming.lei@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 X-BeenThere: linux-nvme@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Sagi Grimberg , Keith Busch , Max Gurtovoy , Alan Adamson , Ming Lei Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-nvme" Errors-To: linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.org blk_mq_freeze_queue_wait() isn't very flexible for some case, such as error recovery: when blk_mq_freeze_queue_wait is called in error recovery handler, new problem may be triggered on this controller, so in-flight IO may not complete when blk_mq_freeze_queue_wait() is called. And error recovery is often run in single context, so dead lock is triggered, because error recover handler can't move on. Add one new API of blk_mq_queue_frozen(), error recovery handler may use this helper to query if the queue has been frozen completely. Meantime, the error recovery handler can check if there is hardware failure happened. If yes, error recovery handler can break from current handling, and run a fresh new recovery, so deadlock can be avoided. This API will be used to improve error handling of nvme-pci's timeout handler. Cc: Christoph Hellwig Cc: Sagi Grimberg Cc: Keith Busch Cc: Max Gurtovoy Signed-off-by: Ming Lei --- block/blk-mq.c | 6 ++++++ include/linux/blk-mq.h | 1 + 2 files changed, 7 insertions(+) diff --git a/block/blk-mq.c b/block/blk-mq.c index cac11945f602..e595951bcdae 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -148,6 +148,12 @@ void blk_mq_freeze_queue_wait(struct request_queue *q) } EXPORT_SYMBOL_GPL(blk_mq_freeze_queue_wait); +bool blk_mq_queue_frozen(struct request_queue *q) +{ + return percpu_ref_is_zero(&q->q_usage_counter); +} +EXPORT_SYMBOL_GPL(blk_mq_queue_frozen); + int blk_mq_freeze_queue_wait_timeout(struct request_queue *q, unsigned long timeout) { diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h index d7307795439a..e1d57202d526 100644 --- a/include/linux/blk-mq.h +++ b/include/linux/blk-mq.h @@ -518,6 +518,7 @@ void blk_freeze_queue_start(struct request_queue *q); void blk_mq_freeze_queue_wait(struct request_queue *q); int blk_mq_freeze_queue_wait_timeout(struct request_queue *q, unsigned long timeout); +bool blk_mq_queue_frozen(struct request_queue *q); int blk_mq_map_queues(struct blk_mq_queue_map *qmap); void blk_mq_update_nr_hw_queues(struct blk_mq_tag_set *set, int nr_hw_queues); -- 2.25.2 _______________________________________________ linux-nvme mailing list linux-nvme@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-nvme