scsi: core: Fix incorrect usage of shost_for_each_device

shost_for_each_device(sdev, shost) \
	for ((sdev) = __scsi_iterate_devices((shost), NULL); \
	     (sdev); \
	     (sdev) = __scsi_iterate_devices((shost), (sdev)))

When terminating shost_for_each_device() iteration with break or return,
scsi_device_put() should be used to prevent stale scsi device references
from being left behind.

Link: https://lore.kernel.org/r/20200518074420.39275-1-yebin10@huawei.com
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Ye Bin <yebin10@huawei.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/scsi_error.c

@@ -1412,6 +1412,7 @@ static int scsi_eh_stu(struct Scsi_Host *shost,
 				sdev_printk(KERN_INFO, sdev,
 					    "%s: skip START_UNIT, past eh deadline\n",
 					    current->comm));
+			scsi_device_put(sdev);
 			break;
 		}
 		stu_scmd = NULL;
@@ -1478,6 +1479,7 @@ static int scsi_eh_bus_device_reset(struct Scsi_Host *shost,
 				sdev_printk(KERN_INFO, sdev,
 					    "%s: skip BDR, past eh deadline\n",
 					     current->comm));
+			scsi_device_put(sdev);
 			break;
 		}
 		bdr_scmd = NULL;

drivers/scsi/scsi_lib.c

@@ -2835,8 +2835,10 @@ scsi_host_unblock(struct Scsi_Host *shost, int new_state)
 
 	shost_for_each_device(sdev, shost) {
 		ret = scsi_internal_device_unblock(sdev, new_state);
-		if (ret)
+		if (ret) {
+			scsi_device_put(sdev);
 			break;
+		}
 	}
 	return ret;
 }