netdev - [PATCH net-next] tcp: assign skb hash after tcp_event_data

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Message-Id: <20210111230552.2704579-1-ycheng@google.com>
Date:   Mon, 11 Jan 2021 15:05:52 -0800
From:   Yuchung Cheng <ycheng@...gle.com>
To:     davem@...emloft.net
Cc:     netdev@...r.kernel.org, edumazet@...gle.com, ncardwell@...gle.com,
        Yuchung Cheng <ycheng@...gle.com>
Subject: [PATCH net-next] tcp: assign skb hash after tcp_event_data_sent

Move skb_set_hash_from_sk s.t. it's called after instead of before
tcp_event_data_sent is called. This enables congestion control
modules to change the socket hash right before restarting from
idle (via the TX_START congestion event).

Signed-off-by: Yuchung Cheng <ycheng@...gle.com>
Signed-off-by: Eric Dumazet <edumazet@...gle.com>
Signed-off-by: Neal Cardwell <ncardwell@...gle.com>
---
 net/ipv4/tcp_output.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index f322e798a351..899d053cb10e 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -1319,7 +1319,6 @@ static int __tcp_transmit_skb(struct sock *sk, struct sk_buff *skb,
 	skb_orphan(skb);
 	skb->sk = sk;
 	skb->destructor = skb_is_tcp_pure_ack(skb) ? __sock_wfree : tcp_wfree;
-	skb_set_hash_from_sk(skb, sk);
 	refcount_add(skb->truesize, &sk->sk_wmem_alloc);
 
 	skb_set_dst_pending_confirm(skb, sk->sk_dst_pending_confirm);
@@ -1390,6 +1389,7 @@ static int __tcp_transmit_skb(struct sock *sk, struct sk_buff *skb,
 			      tcp_skb_pcount(skb));
 
 	tp->segs_out += tcp_skb_pcount(skb);
+	skb_set_hash_from_sk(skb, sk);
 	/* OK, its time to fill skb_shinfo(skb)->gso_{segs|size} */
 	skb_shinfo(skb)->gso_segs = tcp_skb_pcount(skb);
 	skb_shinfo(skb)->gso_size = tcp_skb_mss(skb);
-- 
2.30.0.284.gd98b1dd5eaa7-goog