From: Hannes Reinecke <hare@suse.de>
Date: Wed, 20 Sep 2017 09:18:52 +0200
Subject: [PATCH] scsi: scsi_dh: suppress errors from unsupported devices
References: bsc#1077989
Git-commit: 2930f817132959254db801fe19e61c477293ad6b
Patch-mainline: v4.15-rc1

Device handlers are optional, and for some handlers like ALUA only
implemented for certain device types.  So suppress any errors for
unsupported devices.

Signed-off-by: Hannes Reinecke <hare@suse.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Hannes Reinecke <hare@suse.de>
---
 drivers/scsi/scsi_dh.c    | 19 +++++++++++++------
 drivers/scsi/scsi_priv.h  |  4 ++--
 drivers/scsi/scsi_sysfs.c |  8 +-------
 3 files changed, 16 insertions(+), 15 deletions(-)

diff --git a/drivers/scsi/scsi_dh.c b/drivers/scsi/scsi_dh.c
index ac798d284a7e..2b785d09d5bd 100644
--- a/drivers/scsi/scsi_dh.c
+++ b/drivers/scsi/scsi_dh.c
@@ -140,12 +140,17 @@ static int scsi_dh_handler_attach(struct scsi_device *sdev,
 		case SCSI_DH_RES_TEMP_UNAVAIL:
 			ret = -EAGAIN;
 			break;
+		case SCSI_DH_DEV_UNSUPP:
+		case SCSI_DH_NOSYS:
+			ret = -ENODEV;
+			break;
 		default:
 			ret = -EINVAL;
 			break;
 		}
-		sdev_printk(KERN_ERR, sdev, "%s: Attach failed (%d)\n",
-			    scsi_dh->name, error);
+		if (ret != -ENODEV)
+			sdev_printk(KERN_ERR, sdev, "%s: Attach failed (%d)\n",
+				    scsi_dh->name, error);
 		module_put(scsi_dh->module);
 	} else
 		sdev->handler = scsi_dh;
@@ -164,18 +169,20 @@ static void scsi_dh_handler_detach(struct scsi_device *sdev)
 	module_put(sdev->handler->module);
 }
 
-int scsi_dh_add_device(struct scsi_device *sdev)
+void scsi_dh_add_device(struct scsi_device *sdev)
 {
 	struct scsi_device_handler *devinfo = NULL;
 	const char *drv;
-	int err = 0;
 
 	drv = scsi_dh_find_driver(sdev);
 	if (drv)
 		devinfo = __scsi_dh_lookup(drv);
+	/*
+	 * device_handler is optional, so ignore errors
+	 * from scsi_dh_handler_attach()
+	 */
 	if (devinfo)
-		err = scsi_dh_handler_attach(sdev, devinfo);
-	return err;
+		(void)scsi_dh_handler_attach(sdev, devinfo);
 }
 
 void scsi_dh_release_device(struct scsi_device *sdev)
diff --git a/drivers/scsi/scsi_priv.h b/drivers/scsi/scsi_priv.h
index c11c1f9c912c..889f0258e7a5 100644
--- a/drivers/scsi/scsi_priv.h
+++ b/drivers/scsi/scsi_priv.h
@@ -176,10 +176,10 @@ extern struct async_domain scsi_sd_probe_domain;
 
 /* scsi_dh.c */
 #ifdef CONFIG_SCSI_DH
-int scsi_dh_add_device(struct scsi_device *sdev);
+void scsi_dh_add_device(struct scsi_device *sdev);
 void scsi_dh_release_device(struct scsi_device *sdev);
 #else
-static inline int scsi_dh_add_device(struct scsi_device *sdev) { return 0; }
+static inline void scsi_dh_add_device(struct scsi_device *sdev) { }
 static inline void scsi_dh_release_device(struct scsi_device *sdev) { }
 #endif
 static inline void scsi_dh_remove_device(struct scsi_device *sdev) { }
diff --git a/drivers/scsi/scsi_sysfs.c b/drivers/scsi/scsi_sysfs.c
index 4f22f39557fa..8af1f1caf1c5 100644
--- a/drivers/scsi/scsi_sysfs.c
+++ b/drivers/scsi/scsi_sysfs.c
@@ -1234,13 +1234,7 @@ int scsi_sysfs_add_sdev(struct scsi_device *sdev)
 
 	scsi_autopm_get_device(sdev);
 
-	error = scsi_dh_add_device(sdev);
-	if (error)
-		/*
-		 * device_handler is optional, so any error can be ignored
-		 */
-		sdev_printk(KERN_INFO, sdev,
-				"failed to add device handler: %d\n", error);
+	scsi_dh_add_device(sdev);
 
 	error = device_add(&sdev->sdev_gendev);
 	if (error) {
-- 
2.12.3