From: Yuchung Cheng ycheng@google.com
commit 9c30ae8398b0813e237bde387d67a7f74ab2db2d upstream.
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 Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- include/net/sock.h | 17 ++++++++++++----- net/ipv4/tcp_input.c | 5 ++--- net/ipv4/tcp_timer.c | 22 ++++++++-------------- 3 files changed, 22 insertions(+), 22 deletions(-)
--- a/include/net/sock.h +++ b/include/net/sock.h @@ -1903,10 +1903,13 @@ static inline void sk_set_txhash(struct sk->sk_txhash = net_tx_rndhash(); }
-static inline void sk_rethink_txhash(struct sock *sk) +static inline bool sk_rethink_txhash(struct sock *sk) { - if (sk->sk_txhash) + if (sk->sk_txhash) { sk_set_txhash(sk); + return true; + } + return false; }
static inline struct dst_entry * @@ -1929,12 +1932,10 @@ sk_dst_get(struct sock *sk) return dst; }
-static inline void dst_negative_advice(struct sock *sk) +static inline void __dst_negative_advice(struct sock *sk) { struct dst_entry *ndst, *dst = __sk_dst_get(sk);
- sk_rethink_txhash(sk); - if (dst && dst->ops->negative_advice) { ndst = dst->ops->negative_advice(dst);
@@ -1946,6 +1947,12 @@ static inline void dst_negative_advice(s } }
+static inline void dst_negative_advice(struct sock *sk) +{ + sk_rethink_txhash(sk); + __dst_negative_advice(sk); +} + static inline void __sk_dst_set(struct sock *sk, struct dst_entry *dst) { --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -4379,10 +4379,9 @@ static void tcp_rcv_spurious_retrans(str * 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) --- a/net/ipv4/tcp_timer.c +++ b/net/ipv4/tcp_timer.c @@ -219,14 +219,8 @@ static int tcp_write_timeout(struct sock int retry_until;
if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV)) { - if (icsk->icsk_retransmits) { - dst_negative_advice(sk); - } else { - sk_rethink_txhash(sk); - tp->timeout_rehash++; - __NET_INC_STATS(sock_net(sk), - LINUX_MIB_TCPTIMEOUTREHASH); - } + if (icsk->icsk_retransmits) + __dst_negative_advice(sk); retry_until = icsk->icsk_syn_retries ? : net->ipv4.sysctl_tcp_syn_retries; expired = icsk->icsk_retransmits >= retry_until; } else { @@ -234,12 +228,7 @@ static int tcp_write_timeout(struct sock /* Black hole detection */ tcp_mtu_probing(icsk, sk);
- dst_negative_advice(sk); - } else { - sk_rethink_txhash(sk); - tp->timeout_rehash++; - __NET_INC_STATS(sock_net(sk), - LINUX_MIB_TCPTIMEOUTREHASH); + __dst_negative_advice(sk); }
retry_until = net->ipv4.sysctl_tcp_retries2; @@ -270,6 +259,11 @@ static int tcp_write_timeout(struct sock return 1; }
+ if (sk_rethink_txhash(sk)) { + tp->timeout_rehash++; + __NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPTIMEOUTREHASH); + } + return 0; }