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| author | Eric Dumazet <edumazet@google.com> | 2015-09-15 15:24:20 -0700 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2015-09-17 21:01:04 -0700 |
| commit | 58d607d3e52f2b15902f58a1161da9fb3b0f6d47 (patch) | |
| tree | 1949d88eb7d541878079ddafa607c31017099349 /include/net/sock.h | |
| parent | bbe8373138a1fe92160a18418e7298b4c0128ff1 (diff) | |
| download | lwn-58d607d3e52f2b15902f58a1161da9fb3b0f6d47.tar.gz lwn-58d607d3e52f2b15902f58a1161da9fb3b0f6d47.zip | |
tcp: provide skb->hash to synack packets
In commit b73c3d0e4f0e ("net: Save TX flow hash in sock and set in skbuf
on xmit"), Tom provided a l4 hash to most outgoing TCP packets.
We'd like to provide one as well for SYNACK packets, so that all packets
of a given flow share same txhash, to later enable bonding driver to
also use skb->hash to perform slave selection.
Note that a SYNACK retransmit shuffles the tx hash, as Tom did
in commit 265f94ff54d62 ("net: Recompute sk_txhash on negative routing
advice") for established sockets.
This has nice effect making TCP flows resilient to some kind of black
holes, even at connection establish phase.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Tom Herbert <tom@herbertland.com>
Cc: Mahesh Bandewar <maheshb@google.com>
Acked-by: Tom Herbert <tom@herbertland.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'include/net/sock.h')
| -rw-r--r-- | include/net/sock.h | 12 |
1 files changed, 8 insertions, 4 deletions
diff --git a/include/net/sock.h b/include/net/sock.h index 7aa78440559a..94dff7f566f5 100644 --- a/include/net/sock.h +++ b/include/net/sock.h @@ -1654,12 +1654,16 @@ static inline void sock_graft(struct sock *sk, struct socket *parent) kuid_t sock_i_uid(struct sock *sk); unsigned long sock_i_ino(struct sock *sk); -static inline void sk_set_txhash(struct sock *sk) +static inline u32 net_tx_rndhash(void) { - sk->sk_txhash = prandom_u32(); + u32 v = prandom_u32(); + + return v ?: 1; +} - if (unlikely(!sk->sk_txhash)) - sk->sk_txhash = 1; +static inline void sk_set_txhash(struct sock *sk) +{ + sk->sk_txhash = net_tx_rndhash(); } static inline void sk_rethink_txhash(struct sock *sk) |