From: Ming Lei <ming.lei@redhat.com> To: Jens Axboe <axboe@kernel.dk>, Christoph Hellwig <hch@lst.de> Cc: linux-block@vger.kernel.org, Ming Lei <ming.lei@redhat.com>, Yi Zhang <yi.zhang@redhat.com>, Bart Van Assche <bvanassche@acm.org> Subject: [PATCH V3 2/2] block: mark queue init done at the end of blk_register_queue Date: Wed, 9 Jun 2021 09:58:22 +0800 [thread overview] Message-ID: <20210609015822.103433-3-ming.lei@redhat.com> (raw) In-Reply-To: <20210609015822.103433-1-ming.lei@redhat.com> Mark queue init done when everything is done well in blk_register_queue(), so that wbt_enable_default() can be run quickly without any RCU period involved since adding rq qos requires to freeze queue. Also no any side effect by delaying to mark queue init done. Reported-by: Yi Zhang <yi.zhang@redhat.com> Cc: Bart Van Assche <bvanassche@acm.org> Signed-off-by: Ming Lei <ming.lei@redhat.com> --- block/blk-sysfs.c | 29 +++++++++++++++-------------- 1 file changed, 15 insertions(+), 14 deletions(-) diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c index f89e2fc3963b..370d83c18057 100644 --- a/block/blk-sysfs.c +++ b/block/blk-sysfs.c @@ -866,20 +866,6 @@ int blk_register_queue(struct gendisk *disk) "%s is registering an already registered queue\n", kobject_name(&dev->kobj)); - /* - * SCSI probing may synchronously create and destroy a lot of - * request_queues for non-existent devices. Shutting down a fully - * functional queue takes measureable wallclock time as RCU grace - * periods are involved. To avoid excessive latency in these - * cases, a request_queue starts out in a degraded mode which is - * faster to shut down and is made fully functional here as - * request_queues for non-existent devices never get registered. - */ - if (!blk_queue_init_done(q)) { - blk_queue_flag_set(QUEUE_FLAG_INIT_DONE, q); - percpu_ref_switch_to_percpu(&q->q_usage_counter); - } - blk_queue_update_readahead(q); ret = blk_trace_init_sysfs(dev); @@ -938,6 +924,21 @@ int blk_register_queue(struct gendisk *disk) ret = 0; unlock: mutex_unlock(&q->sysfs_dir_lock); + + /* + * SCSI probing may synchronously create and destroy a lot of + * request_queues for non-existent devices. Shutting down a fully + * functional queue takes measureable wallclock time as RCU grace + * periods are involved. To avoid excessive latency in these + * cases, a request_queue starts out in a degraded mode which is + * faster to shut down and is made fully functional here as + * request_queues for non-existent devices never get registered. + */ + if (!blk_queue_init_done(q)) { + blk_queue_flag_set(QUEUE_FLAG_INIT_DONE, q); + percpu_ref_switch_to_percpu(&q->q_usage_counter); + } + return ret; } EXPORT_SYMBOL_GPL(blk_register_queue); -- 2.31.1
next prev parent reply other threads:[~2021-06-09 1:58 UTC|newest] Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-06-09 1:58 [PATCH V3 0/2] block: fix race between adding wbt and normal IO Ming Lei 2021-06-09 1:58 ` [PATCH V3 1/2] block: fix race between adding/removing rq qos " Ming Lei 2021-06-09 20:05 ` Bart Van Assche 2021-06-09 1:58 ` Ming Lei [this message] 2021-06-09 20:09 ` [PATCH V3 2/2] block: mark queue init done at the end of blk_register_queue Bart Van Assche 2021-06-10 0:45 ` [PATCH V3 0/2] block: fix race between adding wbt and normal IO Yi Zhang 2021-06-14 21:55 ` Ming Lei 2021-06-16 14:11 ` Ming Lei 2021-06-16 14:42 ` Jens Axboe
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