Commit 4a6ce2b6 authored by Wei Wang's avatar Wei Wang Committed by David S. Miller
Browse files

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: default avatarWei Wang <weiwan@google.com>
Acked-by: default avatarMartin KaFai Lau <kafai@fb.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 5f56f409

include/net/dst.h

+1 −0
Original line number Diff line number Diff line
@@ -428,6 +428,7 @@ void dst_init(struct dst_entry *dst, struct dst_ops *ops, 
	      unsigned short flags);

void __dst_free(struct dst_entry *dst);

struct dst_entry *dst_destroy(struct dst_entry *dst);

void dst_dev_put(struct dst_entry *dst);



static inline void dst_free(struct dst_entry *dst)

{

net/core/dst.c

+24 −0
Original line number Diff line number Diff line
@@ -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) {

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