[SRU][Bionic][PATCH 1/2] nvmet-rdma: Don't flush system_wq by default during remove_one

[Joseph Salisbury]

From: Max Gurtovoy <maxg at mellanox.com>

BugLink: http://bugs.launchpad.net/bugs/1764982

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 at mellanox.com>
Signed-off-by: Max Gurtovoy <maxg at mellanox.com>
Reviewed-by: Sagi Grimberg <sagi at grimberg.me>
Signed-off-by: Keith Busch <keith.busch at intel.com>
Signed-off-by: Jens Axboe <axboe at kernel.dk>
(cherry picked from commit a3dd7d0022c347207ae931c753a6dc3e6e8fcbc1)
Signed-off-by: Joseph Salisbury <joseph.salisbury at canonical.com>
---
 drivers/nvme/target/rdma.c | 19 ++++++++++++++++++-
 1 file changed, 18 insertions(+), 1 deletion(-)

diff --git a/drivers/nvme/target/rdma.c b/drivers/nvme/target/rdma.c
index 4991290..f529e2a 100644
--- a/drivers/nvme/target/rdma.c
+++ b/drivers/nvme/target/rdma.c
@@ -1515,8 +1515,25 @@ 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) {
-- 
2.7.4