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net: introduce a new function dst_dev_put()

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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>
This commit is contained in:
Wei Wang 2017-06-17 10:42:28 -07:00 committed by David S. Miller
parent 5f56f409b5
commit 4a6ce2b6f2
2 changed files with 25 additions and 0 deletions
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1
include/net/dst.h
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@ -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)
{

24
net/core/dst.c
View File

@ -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) {