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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 f1342709d1
("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>
This commit is contained in:
parent
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commit
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1 changed files with 1 additions and 1 deletions
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@ -1712,13 +1712,13 @@ static blk_status_t scsi_queue_rq(struct blk_mq_hw_ctx *hctx,
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if (!scsi_host_queue_ready(q, shost, sdev))
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goto out_dec_target_busy;
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clear_bit(SCMD_STATE_COMPLETE, &cmd->state);
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if (!(req->rq_flags & RQF_DONTPREP)) {
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ret = scsi_mq_prep_fn(req);
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if (ret != BLK_STS_OK)
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goto out_dec_host_busy;
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req->rq_flags |= RQF_DONTPREP;
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} else {
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clear_bit(SCMD_STATE_COMPLETE, &cmd->state);
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blk_mq_start_request(req);
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}
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