scsi: Handle MLQUEUE busy response in scsi_send_eh_cmnd

scsi_send_eh_cmnd() is calling queuecommand() directly, so it needs to check the return value here.
The only valid return codes for queuecommand() are 'busy' states, so we need to wait for a bit to allow the LLDD to recover.

Based on an earlier patch from Wen Xiong.

Cc Wen Xiong <[email protected]>

Cc Brian King <[email protected]>

Signed-off-by Hannes Reinecke <[email protected]>

drivers/scsi/scsi_error.c +3 -1

index c1b05a8..1fc6da94 100644
@@ -791,22 +791,32 @@ static int scsi_send_eh_cmnd(struct scsi_cmnd *scmd, unsigned char *cmnd,
 	struct scsi_device *sdev = scmd->device;
 	struct Scsi_Host *shost = sdev->host;
 	DECLARE_COMPLETION_ONSTACK(done);
-	unsigned long timeleft;
+	unsigned long timeleft = timeout;
 	struct scsi_eh_save ses;
+	const int stall_for = min(HZ/10, 1);
 	int rtn;
 
+retry:
 	scsi_eh_prep_cmnd(scmd, &ses, cmnd, cmnd_size, sense_bytes);
 	shost->eh_action = &done;
 
 	scsi_log_send(scmd);

drivers/scsi/scsi_error.c +7 -3

+			goto retry;
+		}
+		rtn = NEEDS_RETRY;
+	} else
+		timeleft = wait_for_completion_timeout(&done, timeout);
 
 	shost->eh_action = NULL;
 
-	scsi_log_completion(scmd, SUCCESS);
+	scsi_log_completion(scmd, rtn);
 
 	SCSI_LOG_ERROR_RECOVERY(3,
 		printk("%s: scmd: %p, timeleft: %ld\n",

@@ -837,7 +847,7 @@ static int scsi_send_eh_cmnd(struct scsi_cmnd *scmd, unsigned char *cmnd,
 			rtn = FAILED;
 			break;
 		}
-	} else {
+	} else if (!rtn) {
 		scsi_abort_eh_cmnd(scmd);
 		rtn = FAILED;
 	}
--

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Quoted 7 lines · Hannes Reinecke

scsi_send_eh_cmnd() is calling queuecommand() directly, so it needs to check the return value here.
The only valid return codes for queuecommand() are 'busy' states, so we need to wait for a bit to allow the LLDD to recover.

Based on an earlier patch from Wen Xiong.

This looks good, only one minor nitpick:

Quoted 23 lines

Cc Wen Xiong <[email protected]>

Cc Brian King <[email protected]>

Signed-off-by Hannes Reinecke <[email protected]>

drivers/scsi/scsi_error.c +3 -1

index c1b05a8..1fc6da94 100644
@@ -791,22 +791,32 @@ static int scsi_send_eh_cmnd(struct scsi_cmnd *scmd, unsigned char *cmnd,
 	struct scsi_device *sdev = scmd->device;
 	struct Scsi_Host *shost = sdev->host;
 	DECLARE_COMPLETION_ONSTACK(done);
-	unsigned long timeleft;
+	unsigned long timeleft = timeout;
 	struct scsi_eh_save ses;
+	const int stall_for = min(HZ/10, 1);
 	int rtn;
 
+retry:
 	scsi_eh_prep_cmnd(scmd, &ses, cmnd, cmnd_size, sense_bytes);
 	shost->eh_action = &done;
 
 	scsi_log_send(scmd);

drivers/scsi/scsi_error.c static int scsi_send_eh_cmnd(struct scsi_cmnd *scmd, unsigned char *cmnd, · line 810

Quoted 10 lines

drivers/scsi/scsi_error.c +6 -3

 	scmd->scsi_done = scsi_eh_done;
-	shost->hostt->queuecommand(shost, scmd);
-
-	timeleft = wait_for_completion_timeout(&done, timeout);
+	rtn = shost->hostt->queuecommand(shost, scmd);
+	if (rtn) {
+		if (timeleft) {
+			scsi_eh_restore_cmnd(scmd, &ses);
+			timeleft -= stall_for;
+			msleep(stall_for);

Stall for is in HZ: need to convert to ms, so

			msleep(stall_for * 1000/HZ);

I also don't see a need to restore and reprep the command each time, but I don't see a problem with it either.