nvmet-rdma: Don't flush system_wq by default during remove_one

The .remove_one function is called for any ib_device removal.
In case the removed device has no reference in our driver, there
is no need to flush the system work queue.
Reviewed-by: Israel Rukshin <israelr@mellanox.com>
Signed-off-by: Max Gurtovoy <maxg@mellanox.com>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

drivers/nvme/target/rdma.c

@@ -1469,8 +1469,25 @@ static struct nvmet_fabrics_ops nvmet_rdma_ops = {
 static void nvmet_rdma_remove_one(struct ib_device *ib_device, void *client_data)
 {
 	struct nvmet_rdma_queue *queue, *tmp;
+	struct nvmet_rdma_device *ndev;
+	bool found = false;
+
+	mutex_lock(&device_list_mutex);
+	list_for_each_entry(ndev, &device_list, entry) {
+		if (ndev->device == ib_device) {
+			found = true;
+			break;
+		}
+	}
+	mutex_unlock(&device_list_mutex);
+
+	if (!found)
+		return;
 
-	/* Device is being removed, delete all queues using this device */
+	/*
+	 * IB Device that is used by nvmet controllers is being removed,
+	 * delete all queues using this device.
+	 */
 	mutex_lock(&nvmet_rdma_queue_mutex);
 	list_for_each_entry_safe(queue, tmp, &nvmet_rdma_queue_list,
 				 queue_list) {