diff options
author | Ming Lei <ming.lei@redhat.com> | 2019-04-12 11:30:32 +0800 |
---|---|---|
committer | Martin K. Petersen <martin.petersen@oracle.com> | 2019-04-15 22:11:22 -0400 |
commit | 18c4f0a42b08ced680aa287a9cf3c94b6f9a752f (patch) | |
tree | b87e6bea0551c833556a529c8b2eb0a8c72970ed /drivers/scsi/scsi_lib.c | |
parent | 1710ac17547ac8b5c44fbd74de41dee3fe26ee81 (diff) | |
download | linux-18c4f0a42b08ced680aa287a9cf3c94b6f9a752f.tar.gz linux-18c4f0a42b08ced680aa287a9cf3c94b6f9a752f.tar.bz2 linux-18c4f0a42b08ced680aa287a9cf3c94b6f9a752f.zip |
scsi: core: don't hold device refcount in IO path
scsi_device's refcount is always grabbed in IO path.
Turns out it isn't necessary, because blk_queue_cleanup() will drain any
in-flight IOs, then cancel timeout/requeue work, and SCSI's requeue_work is
canceled too in __scsi_remove_device().
Also scsi_device won't go away until blk_cleanup_queue() is done.
So don't hold the refcount in IO path, especially the refcount isn't
required in IO path since blk_queue_enter() / blk_queue_exit() is
introduced in the legacy block layer.
Cc: Dongli Zhang <dongli.zhang@oracle.com>
Cc: James Smart <james.smart@broadcom.com>
Cc: Bart Van Assche <bart.vanassche@wdc.com>
Cc: linux-scsi@vger.kernel.org,
Cc: Martin K . Petersen <martin.petersen@oracle.com>,
Cc: Christoph Hellwig <hch@lst.de>,
Cc: James E . J . Bottomley <jejb@linux.vnet.ibm.com>,
Cc: jianchao wang <jianchao.w.wang@oracle.com>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Diffstat (limited to 'drivers/scsi/scsi_lib.c')
-rw-r--r-- | drivers/scsi/scsi_lib.c | 28 |
1 files changed, 2 insertions, 26 deletions
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c index d4bd6cd9d373..6b2570a5642d 100644 --- a/drivers/scsi/scsi_lib.c +++ b/drivers/scsi/scsi_lib.c @@ -141,8 +141,6 @@ scsi_set_blocked(struct scsi_cmnd *cmd, int reason) static void scsi_mq_requeue_cmd(struct scsi_cmnd *cmd) { - struct scsi_device *sdev = cmd->device; - if (cmd->request->rq_flags & RQF_DONTPREP) { cmd->request->rq_flags &= ~RQF_DONTPREP; scsi_mq_uninit_cmd(cmd); @@ -150,7 +148,6 @@ static void scsi_mq_requeue_cmd(struct scsi_cmnd *cmd) WARN_ON_ONCE(true); } blk_mq_requeue_request(cmd->request, true); - put_device(&sdev->sdev_gendev); } /** @@ -189,19 +186,7 @@ static void __scsi_queue_insert(struct scsi_cmnd *cmd, int reason, bool unbusy) */ cmd->result = 0; - /* - * Before a SCSI command is dispatched, - * get_device(&sdev->sdev_gendev) is called and the host, - * target and device busy counters are increased. Since - * requeuing a request causes these actions to be repeated and - * since scsi_device_unbusy() has already been called, - * put_device(&device->sdev_gendev) must still be called. Call - * put_device() after blk_mq_requeue_request() to avoid that - * removal of the SCSI device can start before requeueing has - * happened. - */ blk_mq_requeue_request(cmd->request, true); - put_device(&device->sdev_gendev); } /* @@ -619,7 +604,6 @@ static bool scsi_end_request(struct request *req, blk_status_t error, blk_mq_run_hw_queues(q, true); percpu_ref_put(&q->q_usage_counter); - put_device(&sdev->sdev_gendev); return false; } @@ -1613,7 +1597,6 @@ static void scsi_mq_put_budget(struct blk_mq_hw_ctx *hctx) struct scsi_device *sdev = q->queuedata; atomic_dec(&sdev->device_busy); - put_device(&sdev->sdev_gendev); } static bool scsi_mq_get_budget(struct blk_mq_hw_ctx *hctx) @@ -1621,16 +1604,9 @@ static bool scsi_mq_get_budget(struct blk_mq_hw_ctx *hctx) struct request_queue *q = hctx->queue; struct scsi_device *sdev = q->queuedata; - if (!get_device(&sdev->sdev_gendev)) - goto out; - if (!scsi_dev_queue_ready(q, sdev)) - goto out_put_device; - - return true; + if (scsi_dev_queue_ready(q, sdev)) + return true; -out_put_device: - put_device(&sdev->sdev_gendev); -out: if (atomic_read(&sdev->device_busy) == 0 && !scsi_device_blocked(sdev)) blk_mq_delay_run_hw_queue(hctx, SCSI_QUEUE_DELAY); return false; |