tap: make set_offload a nop after netdev cleanup

virtio-net expects set_offload to succeed after
peer cleanup.
Since we don't have an open fd anymore, make it so.
Fixes warning about the failure of offload setting.

Reported-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

diff --git a/net/tap.c b/net/tap.c
index 937d942..eada34a 100644 (file)
--- a/net/tap.c
+++ b/net/tap.c
@@ -269,8 +269,11 @@ void tap_set_offload(VLANClientState *nc, int csum, int tso4,
                      int tso6, int ecn, int ufo)
 {
     TAPState *s = DO_UPCAST(TAPState, nc, nc);
+    if (s->fd < 0) {
+        return;
+    }
 
-    return tap_fd_set_offload(s->fd, csum, tso4, tso6, ecn, ufo);
+    tap_fd_set_offload(s->fd, csum, tso4, tso6, ecn, ufo);
 }
 
 static void tap_cleanup(VLANClientState *nc)
@@ -290,6 +293,7 @@ static void tap_cleanup(VLANClientState *nc)
     tap_read_poll(s, 0);
     tap_write_poll(s, 0);
     close(s->fd);
+    s->fd = -1;
 }
 
 static void tap_poll(VLANClientState *nc, bool enable)