From 58d607d3e52f2b15902f58a1161da9fb3b0f6d47 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Tue, 15 Sep 2015 15:24:20 -0700 Subject: 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 Cc: Tom Herbert Cc: Mahesh Bandewar Acked-by: Tom Herbert Signed-off-by: David S. Miller --- include/net/sock.h | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) (limited to 'include/net/sock.h') 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) -- cgit v1.2.3-55-g7522