From 0d437906f6dca6167b37c8e1f6f6ec395bde6230 Mon Sep 17 00:00:00 2001 From: Douglas Gilbert Date: Sat, 23 Jun 2018 12:22:19 +0200 Subject: [PATCH] scsi: core: scsi_io_completion hints on fastpath Add likely() and unlikely() hints to conditionals on or near the fastpath. Signed-off-by: Douglas Gilbert Reviewed-by: Johannes Thumshirn Reviewed-by: Bart Van Assche Reviewed-by: Hannes Reinecke Signed-off-by: Martin K. Petersen --- drivers/scsi/scsi_lib.c | 18 +++++++++--------- 1 file changed, 9 insertions(+), 9 deletions(-) diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c index 63dcb2a..19ed11abe 100644 --- a/drivers/scsi/scsi_lib.c +++ b/drivers/scsi/scsi_lib.c @@ -1042,17 +1042,17 @@ void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes) struct request *req = cmd->request; blk_status_t blk_stat = BLK_STS_OK; - if (result) /* does not necessarily mean there is an error */ + if (unlikely(result)) /* a nz result may or may not be an error */ result = scsi_io_completion_nz_result(cmd, result, &blk_stat); - if (blk_rq_is_passthrough(req)) { + if (unlikely(blk_rq_is_passthrough(req))) { /* * scsi_result_to_blk_status may have reset the host_byte */ scsi_req(req)->result = cmd->result; scsi_req(req)->resid_len = scsi_get_resid(cmd); - if (scsi_bidi_cmnd(cmd)) { + if (unlikely(scsi_bidi_cmnd(cmd))) { /* * Bidi commands Must be complete as a whole, * both sides at once. @@ -1065,7 +1065,7 @@ void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes) } } - /* no bidi support for !blk_rq_is_passthrough yet */ + /* no bidi support yet, other than in pass-through */ BUG_ON(blk_bidi_rq(req)); /* @@ -1081,13 +1081,13 @@ void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes) * handle. Failed, zero length commands always need to drop down * to retry code. Fast path should return in this block. */ - if (blk_rq_bytes(req) > 0 || blk_stat == BLK_STS_OK) { - if (!scsi_end_request(req, blk_stat, good_bytes, 0)) + if (likely(blk_rq_bytes(req) > 0 || blk_stat == BLK_STS_OK)) { + if (likely(!scsi_end_request(req, blk_stat, good_bytes, 0))) return; /* no bytes remaining */ } - /* Kill remainder if no retries. */ - if (blk_stat && scsi_noretry_cmd(cmd)) { + /* Kill remainder if no retries. */ + if (unlikely(blk_stat && scsi_noretry_cmd(cmd))) { if (scsi_end_request(req, blk_stat, blk_rq_bytes(req), 0)) BUG(); return; @@ -1097,7 +1097,7 @@ void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes) * If there had been no error, but we have leftover bytes in the * requeues just queue the command up again. */ - if (result == 0) + if (likely(result == 0)) scsi_io_completion_reprep(cmd, q); else scsi_io_completion_action(cmd, result); -- 2.7.4