diff options
| author | Eric Dumazet <edumazet@google.com> | 2014-10-05 18:38:35 -0700 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2014-10-07 13:22:11 -0400 |
| commit | 0287587884b15041203b3a362d485e1ab1f24445 (patch) | |
| tree | 675ae57663c1ba3ee8768e65e7fb0e6d0259e04c /include | |
| parent | fe971b95c22578456ff7198537827841c726d3f7 (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 'include')
| -rw-r--r-- | include/linux/netdevice.h | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h index 2df86f50261c..3a4315b39d20 100644 --- a/include/linux/netdevice.h +++ b/include/linux/netdevice.h @@ -1206,6 +1206,7 @@ enum netdev_priv_flags { IFF_SUPP_NOFCS = 1<<19, IFF_LIVE_ADDR_CHANGE = 1<<20, IFF_MACVLAN = 1<<21, + IFF_XMIT_DST_RELEASE_PERM = 1<<22, }; #define IFF_802_1Q_VLAN IFF_802_1Q_VLAN @@ -1230,6 +1231,7 @@ enum netdev_priv_flags { #define IFF_SUPP_NOFCS IFF_SUPP_NOFCS #define IFF_LIVE_ADDR_CHANGE IFF_LIVE_ADDR_CHANGE #define IFF_MACVLAN IFF_MACVLAN +#define IFF_XMIT_DST_RELEASE_PERM IFF_XMIT_DST_RELEASE_PERM /** * struct net_device - The DEVICE structure. @@ -3588,6 +3590,12 @@ static inline bool netif_supports_nofcs(struct net_device *dev) return dev->priv_flags & IFF_SUPP_NOFCS; } +/* This device needs to keep skb dst for qdisc enqueue or ndo_start_xmit() */ +static inline void netif_keep_dst(struct net_device *dev) +{ + dev->priv_flags &= ~(IFF_XMIT_DST_RELEASE | IFF_XMIT_DST_RELEASE_PERM); +} + extern struct pernet_operations __net_initdata loopback_net_ops; /* Logging, debugging and troubleshooting/diagnostic helpers. */ |