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net: neighbour: use source address of last enqueued packet for solicitation

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Currently we always use the first member of the arp_queue to determine
the sender ip address of the arp packet (or in case of IPv6 - source
address of the ndisc packet). This skb is fixed as long as the queue is
not drained by a complete purge because of a timeout or by a successful
response.

If the first packet enqueued on the arp_queue is from a local application
with a manually set source address and the to be discovered system
does some kind of uRPF checks on the source address in the arp packet
the resolving process hangs until a timeout and restarts. This hurts
communication with the participating network node.

This could be mitigated a bit if we use the latest enqueued skb's
source address for the resolving process, which is not as static as
the arp_queue's head. This change of the source address could result in
better recovery of a failed solicitation.

Cc: "David S. Miller" <davem@davemloft.net>
Cc: Julian Anastasov <ja@ssi.bg>
Reviewed-by: Julian Anastasov <ja@ssi.bg>
Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Hannes Frederic Sowa 2013-09-21 06:32:34 +02:00 committed by David S. Miller
parent fd97ba5d5b
commit 4ed377e36e
1 changed files with 1 additions and 1 deletions
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2
net/core/neighbour.c
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@ -867,7 +867,7 @@ static void neigh_invalidate(struct neighbour *neigh)
static void neigh_probe(struct neighbour *neigh)
__releases(neigh->lock)
{
struct sk_buff *skb = skb_peek(&neigh->arp_queue);
struct sk_buff *skb = skb_peek_tail(&neigh->arp_queue);
/* keep skb alive even if arp_queue overflows */
if (skb)
skb = skb_copy(skb, GFP_ATOMIC);