[PATCH v3] ata: libata-scsi: simplify __ata_scsi_queuecmd()

[Wenchao Hao <haowenchao@huawei.com>]

This is just a clean code. Since each branch of "if" state would check
scmd->cmd_len, so move the check of scmd->cmd_len out of "if" state to
simplify parameters check.

After the check of scmd->cmd_len is out of "if" state, we can remove
one redundant "if" state.

Remove a redundant variable "rc" by hand.

This patch do not change origin function logic.

Signed-off-by: Wenchao Hao <haowenchao@huawei.com>
---
 drivers/ata/libata-scsi.c | 45 ++++++++++++++++++---------------------
 1 file changed, 21 insertions(+), 24 deletions(-)

diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
index a16ef0030..ed8be585a 100644
--- a/drivers/ata/libata-scsi.c
+++ b/drivers/ata/libata-scsi.c
@@ -3958,42 +3958,39 @@ int __ata_scsi_queuecmd(struct scsi_cmnd *scmd, struct ata_device *dev)
 {
 	u8 scsi_op = scmd->cmnd[0];
 	ata_xlat_func_t xlat_func;
-	int rc = 0;
+
+	if (unlikely(!scmd->cmd_len))
+		goto bad_cdb_len;
 
 	if (dev->class == ATA_DEV_ATA || dev->class == ATA_DEV_ZAC) {
-		if (unlikely(!scmd->cmd_len || scmd->cmd_len > dev->cdb_len))
+		if (unlikely(scmd->cmd_len > dev->cdb_len))
 			goto bad_cdb_len;
 
 		xlat_func = ata_get_xlat_func(dev, scsi_op);
-	} else {
-		if (unlikely(!scmd->cmd_len))
-			goto bad_cdb_len;
+	} else if (likely((scsi_op != ATA_16) || !atapi_passthru16)) {
+		/* relay SCSI command to ATAPI device */
+		int len = COMMAND_SIZE(scsi_op);
 
-		xlat_func = NULL;
-		if (likely((scsi_op != ATA_16) || !atapi_passthru16)) {
-			/* relay SCSI command to ATAPI device */
-			int len = COMMAND_SIZE(scsi_op);
-			if (unlikely(len > scmd->cmd_len ||
-				     len > dev->cdb_len ||
-				     scmd->cmd_len > ATAPI_CDB_LEN))
-				goto bad_cdb_len;
+		if (unlikely(len > scmd->cmd_len ||
+			     len > dev->cdb_len ||
+			     scmd->cmd_len > ATAPI_CDB_LEN))
+			goto bad_cdb_len;
 
-			xlat_func = atapi_xlat;
-		} else {
-			/* ATA_16 passthru, treat as an ATA command */
-			if (unlikely(scmd->cmd_len > 16))
-				goto bad_cdb_len;
+		xlat_func = atapi_xlat;
+	} else {
+		/* ATA_16 passthru, treat as an ATA command */
+		if (unlikely(scmd->cmd_len > 16))
+			goto bad_cdb_len;
 
-			xlat_func = ata_get_xlat_func(dev, scsi_op);
-		}
+		xlat_func = ata_get_xlat_func(dev, scsi_op);
 	}
 
 	if (xlat_func)
-		rc = ata_scsi_translate(dev, scmd, xlat_func);
-	else
-		ata_scsi_simulate(dev, scmd);
+		return ata_scsi_translate(dev, scmd, xlat_func);
 
-	return rc;
+	ata_scsi_simulate(dev, scmd);
+
+	return 0;
 
  bad_cdb_len:
 	scmd->result = DID_ERROR << 16;
-- 
2.32.0