net: introduce a new function dst_dev_put()
This function should be called when removing routes from fib tree after
the dst gc is no longer in use.
We first mark DST_OBSOLETE_DEAD on this dst to make sure next
dst_ops->check() fails and returns NULL.
Secondly, as we no longer keep the gc_list, we need to properly
release dst->dev right at the moment when the dst is removed from
the fib/fib6 tree.
It does the following:
1. change dst->input and output pointers to dst_discard/dst_dscard_out to
discard all packets
2. replace dst->dev with loopback interface
Signed-off-by: Wei Wang <weiwan@google.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/core/dst.c b/net/core/dst.c
index 551834c..56998f6 100644
--- a/net/core/dst.c
+++ b/net/core/dst.c
@@ -296,6 +296,30 @@ static void dst_destroy_rcu(struct rcu_head *head)
__dst_free(dst);
}
+/* Operations to mark dst as DEAD and clean up the net device referenced
+ * by dst:
+ * 1. put the dst under loopback interface and discard all tx/rx packets
+ * on this route.
+ * 2. release the net_device
+ * This function should be called when removing routes from the fib tree
+ * in preparation for a NETDEV_DOWN/NETDEV_UNREGISTER event and also to
+ * make the next dst_ops->check() fail.
+ */
+void dst_dev_put(struct dst_entry *dst)
+{
+ struct net_device *dev = dst->dev;
+
+ dst->obsolete = DST_OBSOLETE_DEAD;
+ if (dst->ops->ifdown)
+ dst->ops->ifdown(dst, dev, true);
+ dst->input = dst_discard;
+ dst->output = dst_discard_out;
+ dst->dev = dev_net(dst->dev)->loopback_dev;
+ dev_hold(dst->dev);
+ dev_put(dev);
+}
+EXPORT_SYMBOL(dst_dev_put);
+
void dst_release(struct dst_entry *dst)
{
if (dst) {