ChangeLog:
- add likely() and unlikely() hints to conditionals on or near the
fastpath
- fix a comment in scsi_io_completion_action()
Signed-off-by: Douglas Gilbert <dgilb...@interlog.com>
---
drivers/scsi/scsi_lib.c | 26 ++++++++++++--------------
1 file changed, 12 insertions(+), 14 deletions(-)
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index 8d2d12a69508..23e59281bd02 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -818,7 +818,7 @@ static void scsi_io_completion_action(struct scsi_cmnd
*cmd, int result)
unsigned long wait_for = (cmd->allowed + 1) * req->timeout;
struct scsi_sense_hdr sshdr;
bool sense_valid_and_current = false;
- blk_status_t blk_stat; /* enum, BLK_STS_OK is 0 */
+ blk_status_t blk_stat; /* u8, BLK_STS_OK is only 0 */
/* sense not about current command is termed: deferred */
if (scsi_command_normalize_sense(cmd, &sshdr) &&
@@ -1009,7 +1009,7 @@ 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; /* u8: BLK_STS_OK is only 0 */
- if (result) {
+ if (unlikely(result)) {
blk_stat = scsi_io_completion_nz_result(cmd, result);
if (blk_stat == BLK_STS_OK)
result = 0;
@@ -1017,14 +1017,14 @@ void scsi_io_completion(struct scsi_cmnd *cmd, unsigned
int good_bytes)
blk_stat = BLK_STS_OK;
}
- if (blk_rq_is_passthrough(req)) {
+ if (unlikely(blk_rq_is_passthrough(req))) {
/*
* __scsi_error_from_host_byte 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.
@@ -1037,7 +1037,7 @@ 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));
SCSI_LOG_HLCOMPLETE(1, scmd_printk(KERN_INFO, cmd,
@@ -1049,15 +1049,13 @@ 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))
- return; /* no bytes remaining */
+ 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 retrys.
- */
- if (blk_stat && scsi_noretry_cmd(cmd)) {
+ /* Kill remainder if no retrys */
+ if (unlikely(blk_stat && scsi_noretry_cmd(cmd))) {
if (scsi_end_request(req, blk_stat, blk_rq_bytes(req), 0))
BUG();
return;
@@ -1067,14 +1065,14 @@ 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)) {
/*
* Unprep the request and put it back at the head of the
* queue. A new command will be prepared and issued.
* This block is the same as case ACTION_REPREP in
* scsi_io_completion_action() above.
*/
- if (q->mq_ops)
+ if (likely(q->mq_ops))
scsi_mq_requeue_cmd(cmd);
else {
scsi_release_buffers(cmd);
--
2.14.1
