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authorEric Dumazet <edumazet@google.com>2014-10-05 18:38:35 -0700
committerDavid S. Miller <davem@davemloft.net>2014-10-07 13:22:11 -0400
commit0287587884b15041203b3a362d485e1ab1f24445 (patch)
tree675ae57663c1ba3ee8768e65e7fb0e6d0259e04c /drivers/net/bonding
parentfe971b95c22578456ff7198537827841c726d3f7 (diff)
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/bonding')
-rw-r--r--drivers/net/bonding/bond_main.c9
1 files changed, 6 insertions, 3 deletions
diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
index 3ad5413d4f57..c9ac06cfe6b7 100644
--- a/drivers/net/bonding/bond_main.c
+++ b/drivers/net/bonding/bond_main.c
@@ -1002,7 +1002,8 @@ static netdev_features_t bond_fix_features(struct net_device *dev,
static void bond_compute_features(struct bonding *bond)
{
- unsigned int flags, dst_release_flag = IFF_XMIT_DST_RELEASE;
+ unsigned int dst_release_flag = IFF_XMIT_DST_RELEASE |
+ IFF_XMIT_DST_RELEASE_PERM;
netdev_features_t vlan_features = BOND_VLAN_FEATURES;
netdev_features_t enc_features = BOND_ENC_FEATURES;
struct net_device *bond_dev = bond->dev;
@@ -1038,8 +1039,10 @@ done:
bond_dev->gso_max_segs = gso_max_segs;
netif_set_gso_max_size(bond_dev, gso_max_size);
- flags = bond_dev->priv_flags & ~IFF_XMIT_DST_RELEASE;
- bond_dev->priv_flags = flags | dst_release_flag;
+ bond_dev->priv_flags &= ~IFF_XMIT_DST_RELEASE;
+ if ((bond_dev->priv_flags & IFF_XMIT_DST_RELEASE_PERM) &&
+ dst_release_flag == (IFF_XMIT_DST_RELEASE | IFF_XMIT_DST_RELEASE_PERM))
+ bond_dev->priv_flags |= IFF_XMIT_DST_RELEASE;
netdev_change_features(bond_dev);
}