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Date: Fri, 10 Jul 2020 23:10:53 +0900 From: Kuniyuki Iwashima <kuniyu@...zon.co.jp> To: "David S . Miller" <davem@...emloft.net>, Alexey Kuznetsov <kuznet@....inr.ac.ru>, Hideaki YOSHIFUJI <yoshfuji@...ux-ipv6.org>, "Jakub Kicinski" <kuba@...nel.org>, Eric Dumazet <edumazet@...gle.com> CC: <netdev@...r.kernel.org>, Kuniyuki Iwashima <kuniyu@...zon.co.jp>, Kuniyuki Iwashima <kuni1840@...il.com>, Benjamin Herrenschmidt <benh@...zon.com>, <osa-contribution-log@...zon.com>, Julian Anastasov <ja@....bg> Subject: [PATCH v3 net-next] inet: Remove an unnecessary argument of syn_ack_recalc(). Commit 0c3d79bce48034018e840468ac5a642894a521a3 ("tcp: reduce SYN-ACK retrans for TCP_DEFER_ACCEPT") introduces syn_ack_recalc() which decides if a minisock is held and a SYN+ACK is retransmitted or not. If rskq_defer_accept is not zero in syn_ack_recalc(), max_retries always has the same value because max_retries is overwritten by rskq_defer_accept in reqsk_timer_handler(). This commit adds three changes: - remove redundant non-zero check for rskq_defer_accept in reqsk_timer_handler(). - remove max_retries from the arguments of syn_ack_recalc() and use rskq_defer_accept instead. - rename thresh to max_syn_ack_retries for readability. Signed-off-by: Kuniyuki Iwashima <kuniyu@...zon.co.jp> Reviewed-by: Benjamin Herrenschmidt <benh@...zon.com> CC: Julian Anastasov <ja@....bg> --- net/ipv4/inet_connection_sock.c | 33 +++++++++++++++------------------ 1 file changed, 15 insertions(+), 18 deletions(-) diff --git a/net/ipv4/inet_connection_sock.c b/net/ipv4/inet_connection_sock.c index afaf582a5aa9..21bc80a3c7cf 100644 --- a/net/ipv4/inet_connection_sock.c +++ b/net/ipv4/inet_connection_sock.c @@ -648,20 +648,23 @@ struct dst_entry *inet_csk_route_child_sock(const struct sock *sk, EXPORT_SYMBOL_GPL(inet_csk_route_child_sock); /* Decide when to expire the request and when to resend SYN-ACK */ -static inline void syn_ack_recalc(struct request_sock *req, const int thresh, - const int max_retries, +static inline void syn_ack_recalc(struct request_sock *req, + const int max_syn_ack_retries, const u8 rskq_defer_accept, int *expire, int *resend) { if (!rskq_defer_accept) { - *expire = req->num_timeout >= thresh; + *expire = req->num_timeout >= max_syn_ack_retries; *resend = 1; return; } - *expire = req->num_timeout >= thresh && - (!inet_rsk(req)->acked || req->num_timeout >= max_retries); - /* - * Do not resend while waiting for data after ACK, + /* If a bare ACK has already been dropped, the client is alive, so + * do not free the request_sock to drop a bare ACK at most + * rskq_defer_accept times and wait for data. + */ + *expire = req->num_timeout >= max_syn_ack_retries && + (!inet_rsk(req)->acked || req->num_timeout >= rskq_defer_accept); + /* Do not resend while waiting for data after ACK, * start to resend on end of deferring period to give * last chance for data or ACK to create established socket. */ @@ -720,15 +723,12 @@ static void reqsk_timer_handler(struct timer_list *t) struct net *net = sock_net(sk_listener); struct inet_connection_sock *icsk = inet_csk(sk_listener); struct request_sock_queue *queue = &icsk->icsk_accept_queue; - int qlen, expire = 0, resend = 0; - int max_retries, thresh; - u8 defer_accept; + int max_syn_ack_retries, qlen, expire = 0, resend = 0; if (inet_sk_state_load(sk_listener) != TCP_LISTEN) goto drop; - max_retries = icsk->icsk_syn_retries ? : net->ipv4.sysctl_tcp_synack_retries; - thresh = max_retries; + max_syn_ack_retries = icsk->icsk_syn_retries ? : net->ipv4.sysctl_tcp_synack_retries; /* Normally all the openreqs are young and become mature * (i.e. converted to established socket) for first timeout. * If synack was not acknowledged for 1 second, it means @@ -750,17 +750,14 @@ static void reqsk_timer_handler(struct timer_list *t) if ((qlen << 1) > max(8U, READ_ONCE(sk_listener->sk_max_ack_backlog))) { int young = reqsk_queue_len_young(queue) << 1; - while (thresh > 2) { + while (max_syn_ack_retries > 2) { if (qlen < young) break; - thresh--; + max_syn_ack_retries--; young <<= 1; } } - defer_accept = READ_ONCE(queue->rskq_defer_accept); - if (defer_accept) - max_retries = defer_accept; - syn_ack_recalc(req, thresh, max_retries, defer_accept, + syn_ack_recalc(req, max_syn_ack_retries, READ_ONCE(queue->rskq_defer_accept), &expire, &resend); req->rsk_ops->syn_ack_timeout(req); if (!expire && -- 2.17.2 (Apple Git-113)
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