scsi: scsi_dh_alua: Ensure that alua_activate() calls the completion function

Callers of scsi_dh_activate(), e.g. dm-mpath, assume that this function
either returns an error code or calls the completion function. Make
alua_activate() call the completion function even if scsi_device_get()
fails.
Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Tang Junhui <tang.junhui@zte.com.cn>
Cc: <stable@vger.kernel.org>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/device_handler/scsi_dh_alua.c

@@ -113,7 +113,7 @@ struct alua_queue_data {
 #define ALUA_POLICY_SWITCH_ALL		1
 
 static void alua_rtpg_work(struct work_struct *work);
-static void alua_rtpg_queue(struct alua_port_group *pg,
+static bool alua_rtpg_queue(struct alua_port_group *pg,
 			    struct scsi_device *sdev,
 			    struct alua_queue_data *qdata, bool force);
 static void alua_check(struct scsi_device *sdev, bool force);
@@ -862,7 +862,13 @@ static void alua_rtpg_work(struct work_struct *work)
 	kref_put(&pg->kref, release_port_group);
 }
 
-static void alua_rtpg_queue(struct alua_port_group *pg,
+/**
+ * alua_rtpg_queue() - cause RTPG to be submitted asynchronously
+ *
+ * Returns true if and only if alua_rtpg_work() will be called asynchronously.
+ * That function is responsible for calling @qdata->fn().
+ */
+static bool alua_rtpg_queue(struct alua_port_group *pg,
 			    struct scsi_device *sdev,
 			    struct alua_queue_data *qdata, bool force)
 {
@@ -871,7 +877,7 @@ static void alua_rtpg_queue(struct alua_port_group *pg,
 	struct workqueue_struct *alua_wq = kaluad_wq;
 
 	if (!pg || scsi_device_get(sdev))
-		return;
+		return false;
 
 	spin_lock_irqsave(&pg->lock, flags);
 	if (qdata) {
@@ -907,6 +913,8 @@ static void alua_rtpg_queue(struct alua_port_group *pg,
 	}
 	if (sdev)
 		scsi_device_put(sdev);
+
+	return true;
 }
 
 /*
@@ -1007,11 +1015,13 @@ static int alua_activate(struct scsi_device *sdev,
 		mutex_unlock(&h->init_mutex);
 		goto out;
 	}
-	fn = NULL;
 	rcu_read_unlock();
 	mutex_unlock(&h->init_mutex);
 
-	alua_rtpg_queue(pg, sdev, qdata, true);
+	if (alua_rtpg_queue(pg, sdev, qdata, true))
+		fn = NULL;
+	else
+		err = SCSI_DH_DEV_OFFLINED;
 	kref_put(&pg->kref, release_port_group);
 out:
 	if (fn)