tcp: fix TCP socket rehash stats mis-accounting
The previous commit 32efcc06d2a1 ("tcp: export count for rehash attempts")
would mis-account rehashing SNMP and socket stats:
a. During handshake of an active open, only counts the first
SYN timeout
b. After handshake of passive and active open, stop updating
after (roughly) TCP_RETRIES1 recurring RTOs
c. After the socket aborts, over count timeout_rehash by 1
This patch fixes this by checking the rehash result from sk_rethink_txhash.
Fixes: 32efcc06d2a1 ("tcp: export count for rehash attempts")
Signed-off-by: Yuchung Cheng <ycheng@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Neal Cardwell <ncardwell@google.com>
Link: https://lore.kernel.org/r/20210119192619.1848270-1-ycheng@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index bafcab7..a7dfca0 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -4397,10 +4397,9 @@ static void tcp_rcv_spurious_retrans(struct sock *sk, const struct sk_buff *skb)
* The receiver remembers and reflects via DSACKs. Leverage the
* DSACK state and change the txhash to re-route speculatively.
*/
- if (TCP_SKB_CB(skb)->seq == tcp_sk(sk)->duplicate_sack[0].start_seq) {
- sk_rethink_txhash(sk);
+ if (TCP_SKB_CB(skb)->seq == tcp_sk(sk)->duplicate_sack[0].start_seq &&
+ sk_rethink_txhash(sk))
NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPDUPLICATEDATAREHASH);
- }
}
static void tcp_send_dupack(struct sock *sk, const struct sk_buff *skb)