1 files changed, 44 insertions, 20 deletions

diff --git a/drivers/scsi/scsi.c b/drivers/scsi/scsi.c
index a77e0499b738..518a252eb6aa 100644
--- a/drivers/scsi/scsi.c
+++ b/drivers/scsi/scsi.c
@@ -510,22 +510,34 @@ void scsi_attach_vpd(struct scsi_device *sdev)
 		return;
 
 	for (i = 4; i < vpd_buf->len; i++) {
-		if (vpd_buf->data[i] == 0x0)
+		switch (vpd_buf->data[i]) {
+		case 0x0:
 			scsi_update_vpd_page(sdev, 0x0, &sdev->vpd_pg0);
-		if (vpd_buf->data[i] == 0x80)
+			break;
+		case 0x80:
 			scsi_update_vpd_page(sdev, 0x80, &sdev->vpd_pg80);
-		if (vpd_buf->data[i] == 0x83)
+			break;
+		case 0x83:
 			scsi_update_vpd_page(sdev, 0x83, &sdev->vpd_pg83);
-		if (vpd_buf->data[i] == 0x89)
+			break;
+		case 0x89:
 			scsi_update_vpd_page(sdev, 0x89, &sdev->vpd_pg89);
-		if (vpd_buf->data[i] == 0xb0)
+			break;
+		case 0xb0:
 			scsi_update_vpd_page(sdev, 0xb0, &sdev->vpd_pgb0);
-		if (vpd_buf->data[i] == 0xb1)
+			break;
+		case 0xb1:
 			scsi_update_vpd_page(sdev, 0xb1, &sdev->vpd_pgb1);
-		if (vpd_buf->data[i] == 0xb2)
+			break;
+		case 0xb2:
 			scsi_update_vpd_page(sdev, 0xb2, &sdev->vpd_pgb2);
-		if (vpd_buf->data[i] == 0xb7)
+			break;
+		case 0xb7:
 			scsi_update_vpd_page(sdev, 0xb7, &sdev->vpd_pgb7);
+			break;
+		default:
+			break;
+		}
 	}
 	kfree(vpd_buf);
 }
@@ -695,26 +707,23 @@ void scsi_cdl_check(struct scsi_device *sdev)
  */
 int scsi_cdl_enable(struct scsi_device *sdev, bool enable)
 {
-	struct scsi_mode_data data;
-	struct scsi_sense_hdr sshdr;
-	struct scsi_vpd *vpd;
-	bool is_ata = false;
 	char buf[64];
+	bool is_ata;
 	int ret;
 
 	if (!sdev->cdl_supported)
 		return -EOPNOTSUPP;
 
 	rcu_read_lock();
-	vpd = rcu_dereference(sdev->vpd_pg89);
-	if (vpd)
-		is_ata = true;
+	is_ata = rcu_dereference(sdev->vpd_pg89);
 	rcu_read_unlock();
 
 	/*
 	 * For ATA devices, CDL needs to be enabled with a SET FEATURES command.
 	 */
 	if (is_ata) {
+		struct scsi_mode_data data;
+		struct scsi_sense_hdr sshdr;
 		char *buf_data;
 		int len;
 
@@ -723,16 +732,30 @@ int scsi_cdl_enable(struct scsi_device *sdev, bool enable)
 		if (ret)
 			return -EINVAL;
 
-		/* Enable CDL using the ATA feature page */
+		/* Enable or disable CDL using the ATA feature page */
 		len = min_t(size_t, sizeof(buf),
 			    data.length - data.header_length -
 			    data.block_descriptor_length);
 		buf_data = buf + data.header_length +
 			data.block_descriptor_length;
-		if (enable)
-			buf_data[4] = 0x02;
-		else
-			buf_data[4] = 0;
+
+		/*
+		 * If we want to enable CDL and CDL is already enabled on the
+		 * device, do nothing. This avoids needlessly resetting the CDL
+		 * statistics on the device as that is implied by the CDL enable
+		 * action. Similar to this, there is no need to do anything if
+		 * we want to disable CDL and CDL is already disabled.
+		 */
+		if (enable) {
+			if ((buf_data[4] & 0x03) == 0x02)
+				goto out;
+			buf_data[4] &= ~0x03;
+			buf_data[4] |= 0x02;
+		} else {
+			if ((buf_data[4] & 0x03) == 0x00)
+				goto out;
+			buf_data[4] &= ~0x03;
+		}
 
 		ret = scsi_mode_select(sdev, 1, 0, buf_data, len, 5 * HZ, 3,
 				       &data, &sshdr);
@@ -744,6 +767,7 @@ int scsi_cdl_enable(struct scsi_device *sdev, bool enable)
 		}
 	}
 
+out:
 	sdev->cdl_enable = enable;
 
 	return 0;