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authorJarek Poplawski <jarkao2@gmail.com>2009-04-17 06:08:49 -0400
committerDavid S. Miller <davem@davemloft.net>2009-04-20 05:14:59 -0400
commit8caf153974f2274301e583fda732cc8e5b80331f (patch)
treed7f52b67e74b4bb4c81f2a4c34dae912a608f6fc /net/core/dev.c
parentc7c1a0f60b90955855ba8cd9cfc480167bf6c3da (diff)
net: sch_netem: Fix an inconsistency in ingress netem timestamps.
Alex Sidorenko reported: "while experimenting with 'netem' we have found some strange behaviour. It seemed that ingress delay as measured by 'ping' command shows up on some hosts but not on others. After some investigation I have found that the problem is that skbuff->tstamp field value depends on whether there are any packet sniffers enabled. That is: - if any ptype_all handler is registered, the tstamp field is as expected - if there are no ptype_all handlers, the tstamp field does not show the delay" This patch prevents unnecessary update of tstamp in dev_queue_xmit_nit() on ingress path (with act_mirred) adding a check, so minimal overhead on the fast path, but only when sniffers etc. are active. Since netem at ingress seems to logically emulate a network before a host, tstamp is zeroed to trigger the update and pretend delays are from the outside. Reported-by: Alex Sidorenko <alexandre.sidorenko@hp.com> Tested-by: Alex Sidorenko <alexandre.sidorenko@hp.com> Signed-off-by: Jarek Poplawski <jarkao2@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/core/dev.c')
-rw-r--r--net/core/dev.c5
1 files changed, 5 insertions, 0 deletions
diff --git a/net/core/dev.c b/net/core/dev.c
index 343883f65ea7..dcc357e4f91e 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -1336,7 +1336,12 @@ static void dev_queue_xmit_nit(struct sk_buff *skb, struct net_device *dev)
1336{ 1336{
1337 struct packet_type *ptype; 1337 struct packet_type *ptype;
1338 1338
1339#ifdef CONFIG_NET_CLS_ACT
1340 if (!(skb->tstamp.tv64 && (G_TC_FROM(skb->tc_verd) & AT_INGRESS)))
1341 net_timestamp(skb);
1342#else
1339 net_timestamp(skb); 1343 net_timestamp(skb);
1344#endif
1340 1345
1341 rcu_read_lock(); 1346 rcu_read_lock();
1342 list_for_each_entry_rcu(ptype, &ptype_all, list) { 1347 list_for_each_entry_rcu(ptype, &ptype_all, list) {