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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 /drivers/net/loopback.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 'drivers/net/loopback.c')
-rw-r--r--drivers/net/loopback.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/net/loopback.c b/drivers/net/loopback.c
index 8f2262540561..c76283c2f84a 100644
--- a/drivers/net/loopback.c
+++ b/drivers/net/loopback.c
@@ -169,7 +169,7 @@ static void loopback_setup(struct net_device *dev)
dev->type = ARPHRD_LOOPBACK; /* 0x0001*/
dev->flags = IFF_LOOPBACK;
dev->priv_flags |= IFF_LIVE_ADDR_CHANGE;
- dev->priv_flags &= ~IFF_XMIT_DST_RELEASE;
+ netif_keep_dst(dev);
dev->hw_features = NETIF_F_ALL_TSO | NETIF_F_UFO;
dev->features = NETIF_F_SG | NETIF_F_FRAGLIST
| NETIF_F_ALL_TSO