IB/core: Add missing check for addr_resolve callback return value

When calling rdma_resolve_ip inside rdma_addr_find_l2_eth_by_grh,
the return status of the request was ignored in the callback function
causing a successful return and an empty dmac.

Signed-off-by: Mark Bloch <markb@mellanox.com>
Signed-off-by: Alex Vesker <valex@mellanox.com>
Reviewed-by: Or Gerlitz <ogerlitz@mellanox.com>
Signed-off-by: Leon Romanovsky <leon@kernel.org>
Signed-off-by: Doug Ledford <dledford@redhat.com>

drivers/infiniband/core/addr.c

@@ -699,13 +699,16 @@ EXPORT_SYMBOL(rdma_addr_cancel);
 struct resolve_cb_context {
 	struct rdma_dev_addr *addr;
 	struct completion comp;
+	int status;
 };
 
 static void resolve_cb(int status, struct sockaddr *src_addr,
 	     struct rdma_dev_addr *addr, void *context)
 {
-	memcpy(((struct resolve_cb_context *)context)->addr, addr, sizeof(struct
-				rdma_dev_addr));
+	if (!status)
+		memcpy(((struct resolve_cb_context *)context)->addr,
+		       addr, sizeof(struct rdma_dev_addr));
+	((struct resolve_cb_context *)context)->status = status;
 	complete(&((struct resolve_cb_context *)context)->comp);
 }
 
@@ -743,6 +746,10 @@ int rdma_addr_find_l2_eth_by_grh(const union ib_gid *sgid,
 
 	wait_for_completion(&ctx.comp);
 
+	ret = ctx.status;
+	if (ret)
+		return ret;
+
 	memcpy(dmac, dev_addr.dst_dev_addr, ETH_ALEN);
 	dev = dev_get_by_index(&init_net, dev_addr.bound_dev_if);
 	if (!dev)