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authorEric Dumazet <edumazet@google.com>2014-10-06 05:38:35 +0400
committerDavid S. Miller <davem@davemloft.net>2014-10-07 21:22:11 +0400
commit0287587884b15041203b3a362d485e1ab1f24445 (patch)
tree675ae57663c1ba3ee8768e65e7fb0e6d0259e04c /net/sched/cls_flow.c
parentfe971b95c22578456ff7198537827841c726d3f7 (diff)
downloadlinux-0287587884b15041203b3a362d485e1ab1f24445.tar.xz
net: better IFF_XMIT_DST_RELEASE support
Testing xmit_more support with netperf and connected UDP sockets, I found strange dst refcount false sharing. Current handling of IFF_XMIT_DST_RELEASE is not optimal. Dropping dst in validate_xmit_skb() is certainly too late in case packet was queued by cpu X but dequeued by cpu Y The logical point to take care of drop/force is in __dev_queue_xmit() before even taking qdisc lock. As Julian Anastasov pointed out, need for skb_dst() might come from some packet schedulers or classifiers. This patch adds new helper to cleanly express needs of various drivers or qdiscs/classifiers. Drivers that need skb_dst() in their ndo_start_xmit() should call following helper in their setup instead of the prior : dev->priv_flags &= ~IFF_XMIT_DST_RELEASE; -> netif_keep_dst(dev); Instead of using a single bit, we use two bits, one being eventually rebuilt in bonding/team drivers. The other one, is permanent and blocks IFF_XMIT_DST_RELEASE being rebuilt in bonding/team. Eventually, we could add something smarter later. Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Julian Anastasov <ja@ssi.bg> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/sched/cls_flow.c')
-rw-r--r--net/sched/cls_flow.c2
1 files changed, 2 insertions, 0 deletions
diff --git a/net/sched/cls_flow.c b/net/sched/cls_flow.c
index a5d2b20db560..4ac515f2a6ce 100644
--- a/net/sched/cls_flow.c
+++ b/net/sched/cls_flow.c
@@ -493,6 +493,8 @@ static int flow_change(struct net *net, struct sk_buff *in_skb,
tcf_exts_change(tp, &fnew->exts, &e);
tcf_em_tree_change(tp, &fnew->ematches, &t);
+ netif_keep_dst(qdisc_dev(tp->q));
+
if (tb[TCA_FLOW_KEYS]) {
fnew->keymask = keymask;
fnew->nkeys = nkeys;