ata: libata-eh: Cleanup ata_scsi_cmd_error_handler()

If ap->ops->error_handler is NULL just return. This patch also
fixes some comment style issue.
Signed-off-by: Wenchao Hao <haowenchao@huawei.com>
Reviewed-by: Niklas Cassel <niklas.cassel@wdc.com>
Signed-off-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>

drivers/ata/libata-eh.c

@@ -565,13 +565,19 @@ void ata_scsi_cmd_error_handler(struct Scsi_Host *host, struct ata_port *ap,
 {
 	int i;
 	unsigned long flags;
+	struct scsi_cmnd *scmd, *tmp;
+	int nr_timedout = 0;
 
 	/* make sure sff pio task is not running */
 	ata_sff_flush_pio_task(ap);
 
+	if (!ap->ops->error_handler)
+		return;
+
 	/* synchronize with host lock and sort out timeouts */
 
-	/* For new EH, all qcs are finished in one of three ways -
+	/*
+	 * For new EH, all qcs are finished in one of three ways -
 	 * normal completion, error completion, and SCSI timeout.
 	 * Both completions can race against SCSI timeout.  When normal
 	 * completion wins, the qc never reaches EH.  When error
@@ -584,64 +590,61 @@ void ata_scsi_cmd_error_handler(struct Scsi_Host *host, struct ata_port *ap,
 	 * timed out iff its associated qc is active and not failed.
 	 */
 	spin_lock_irqsave(ap->lock, flags);
-	if (ap->ops->error_handler) {
-		struct scsi_cmnd *scmd, *tmp;
-		int nr_timedout = 0;
-
-		/* This must occur under the ap->lock as we don't want
-		   a polled recovery to race the real interrupt handler
-
-		   The lost_interrupt handler checks for any completed but
-		   non-notified command and completes much like an IRQ handler.
 
-		   We then fall into the error recovery code which will treat
-		   this as if normal completion won the race */
-
-		if (ap->ops->lost_interrupt)
-			ap->ops->lost_interrupt(ap);
+	/*
+	 * This must occur under the ap->lock as we don't want
+	 * a polled recovery to race the real interrupt handler
+	 *
+	 * The lost_interrupt handler checks for any completed but
+	 * non-notified command and completes much like an IRQ handler.
+	 *
+	 * We then fall into the error recovery code which will treat
+	 * this as if normal completion won the race
+	 */
+	if (ap->ops->lost_interrupt)
+		ap->ops->lost_interrupt(ap);
 
-		list_for_each_entry_safe(scmd, tmp, eh_work_q, eh_entry) {
-			struct ata_queued_cmd *qc;
+	list_for_each_entry_safe(scmd, tmp, eh_work_q, eh_entry) {
+		struct ata_queued_cmd *qc;
 
-			ata_qc_for_each_raw(ap, qc, i) {
-				if (qc->flags & ATA_QCFLAG_ACTIVE &&
-				    qc->scsicmd == scmd)
-					break;
-			}
+		ata_qc_for_each_raw(ap, qc, i) {
+			if (qc->flags & ATA_QCFLAG_ACTIVE &&
+			    qc->scsicmd == scmd)
+				break;
+		}
 
-			if (i < ATA_MAX_QUEUE) {
-				/* the scmd has an associated qc */
-				if (!(qc->flags & ATA_QCFLAG_FAILED)) {
-					/* which hasn't failed yet, timeout */
-					qc->err_mask |= AC_ERR_TIMEOUT;
-					qc->flags |= ATA_QCFLAG_FAILED;
-					nr_timedout++;
-				}
-			} else {
-				/* Normal completion occurred after
-				 * SCSI timeout but before this point.
-				 * Successfully complete it.
-				 */
-				scmd->retries = scmd->allowed;
-				scsi_eh_finish_cmd(scmd, &ap->eh_done_q);
+		if (i < ATA_MAX_QUEUE) {
+			/* the scmd has an associated qc */
+			if (!(qc->flags & ATA_QCFLAG_FAILED)) {
+				/* which hasn't failed yet, timeout */
+				qc->err_mask |= AC_ERR_TIMEOUT;
+				qc->flags |= ATA_QCFLAG_FAILED;
+				nr_timedout++;
 			}
+		} else {
+			/* Normal completion occurred after
+			 * SCSI timeout but before this point.
+			 * Successfully complete it.
+			 */
+			scmd->retries = scmd->allowed;
+			scsi_eh_finish_cmd(scmd, &ap->eh_done_q);
 		}
+	}
 
-		/* If we have timed out qcs.  They belong to EH from
-		 * this point but the state of the controller is
-		 * unknown.  Freeze the port to make sure the IRQ
-		 * handler doesn't diddle with those qcs.  This must
-		 * be done atomically w.r.t. setting QCFLAG_FAILED.
-		 */
-		if (nr_timedout)
-			__ata_port_freeze(ap);
+	/*
+	 * If we have timed out qcs.  They belong to EH from
+	 * this point but the state of the controller is
+	 * unknown.  Freeze the port to make sure the IRQ
+	 * handler doesn't diddle with those qcs.  This must
+	 * be done atomically w.r.t. setting QCFLAG_FAILED.
+	 */
+	if (nr_timedout)
+		__ata_port_freeze(ap);
 
+	/* initialize eh_tries */
+	ap->eh_tries = ATA_EH_MAX_TRIES;
 
-		/* initialize eh_tries */
-		ap->eh_tries = ATA_EH_MAX_TRIES;
-	}
 	spin_unlock_irqrestore(ap->lock, flags);
-
 }
 EXPORT_SYMBOL(ata_scsi_cmd_error_handler);