IB/iser: Protect completion context active_qps update

As iser connections can share completion contexts, we need
to protect the active_qps update each time we set it.
Signed-off-by: NMax Gurtovoy <maxg@mellanox.com>
Acked-by: NSagi Grimberg <sagi@grimberg.me>
Signed-off-by: NDoug Ledford <dledford@redhat.com>

drivers/infiniband/ulp/iser/iser_verbs.c

@@ -597,7 +597,9 @@ static void iser_free_ib_conn_res(struct iser_conn *iser_conn,
 		  iser_conn, ib_conn->cma_id, ib_conn->qp);
 
 	if (ib_conn->qp != NULL) {
+		mutex_lock(&ig.connlist_mutex);
 		ib_conn->comp->active_qps--;
+		mutex_unlock(&ig.connlist_mutex);
 		rdma_destroy_qp(ib_conn->cma_id);
 		ib_conn->qp = NULL;
 	}