migration/rdma: cleanup rdma context before g_free to avoid memleaks

When error happen in initializing 'rdma_return_path', we should cleanup rdma context
before g_free(rdma) to avoid some memleaks. This patch fix that.

Reported-by: Euler Robot <euler.robot@huawei.com>
Signed-off-by: Pan Nengyuan <pannengyuan@huawei.com>
Message-Id: <20200508100755.7875-3-pannengyuan@huawei.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

migration/rdma.c

@@ -4094,20 +4094,20 @@ void rdma_start_outgoing_migration(void *opaque,
         rdma_return_path = qemu_rdma_data_init(host_port, errp);
 
         if (rdma_return_path == NULL) {
-            goto err;
+            goto return_path_err;
         }
 
         ret = qemu_rdma_source_init(rdma_return_path,
             s->enabled_capabilities[MIGRATION_CAPABILITY_RDMA_PIN_ALL], errp);
 
         if (ret) {
-            goto err;
+            goto return_path_err;
         }
 
         ret = qemu_rdma_connect(rdma_return_path, errp);
 
         if (ret) {
-            goto err;
+            goto return_path_err;
         }
 
         rdma->return_path = rdma_return_path;
@@ -4120,6 +4120,8 @@ void rdma_start_outgoing_migration(void *opaque,
     s->to_dst_file = qemu_fopen_rdma(rdma, "wb");
     migrate_fd_connect(s, NULL);
     return;
+return_path_err:
+    qemu_rdma_cleanup(rdma);
 err:
     g_free(rdma);
     g_free(rdma_return_path);