diff options
| author | Bart Van Assche | 2019-01-15 16:50:03 -0800 |
|---|---|---|
| committer | Martin K. Petersen | 2019-01-22 21:18:27 -0500 |
| commit | cd464d838041b3a69464c0dd3938c1f912487bd3 (patch) | |
| tree | b4e0e9b9287603e730727eb9cfd2aa941c19f778 | |
| parent | cf64e5a5f6a5f602f7ef46897da4f70968e11fbc (diff) | |
scsi: core: Remove an atomic instruction from the hot path
From scsi_init_command(), a function called by scsi_mq_prep_fn():
/* zero out the cmd, except for the embedded scsi_request */
memset((char *)cmd + sizeof(cmd->req), 0,
sizeof(*cmd) - sizeof(cmd->req) + dev->host->hostt->cmd_size);
In other words, scsi_mq_prep_fn() clears scsi_cmnd.flags. Hence move the
clear_bit() call into the else branch, the only branch in which this code
is necessary.
See also commit f1342709d18a ("scsi: Do not rely on blk-mq for double
completions").
Cc: Keith Busch <keith.busch@intel.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Hannes Reinecke <hare@suse.com>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
| -rw-r--r-- | drivers/scsi/scsi_lib.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c index b13cc9288ba0..00cd365fb7d2 100644 --- a/drivers/scsi/scsi_lib.c +++ b/drivers/scsi/scsi_lib.c @@ -1712,13 +1712,13 @@ static blk_status_t scsi_queue_rq(struct blk_mq_hw_ctx *hctx, if (!scsi_host_queue_ready(q, shost, sdev)) goto out_dec_target_busy; - clear_bit(SCMD_STATE_COMPLETE, &cmd->state); if (!(req->rq_flags & RQF_DONTPREP)) { ret = scsi_mq_prep_fn(req); if (ret != BLK_STS_OK) goto out_dec_host_busy; req->rq_flags |= RQF_DONTPREP; } else { + clear_bit(SCMD_STATE_COMPLETE, &cmd->state); blk_mq_start_request(req); } |