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Commit b1062596 authored by Eric Dumazet's avatar Eric Dumazet Committed by Greg Kroah-Hartman
Browse files

tcp: annotate data-races around fastopenq.max_qlen 



[ Upstream commit 70f360dd7042cb843635ece9d28335a4addff9eb ]

This field can be read locklessly.

Fixes: 1536e285 ("tcp: Add a TCP_FASTOPEN socket option to get a max backlog on its listner")
Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Link: https://lore.kernel.org/r/20230719212857.3943972-12-edumazet@google.com


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
parent 21c325d0

include/linux/tcp.h

+1 −1
Original line number Diff line number Diff line
@@ -458,7 +458,7 @@ static inline void fastopen_queue_tune(struct sock *sk, int backlog) 
	struct request_sock_queue *queue = &inet_csk(sk)->icsk_accept_queue;

	int somaxconn = READ_ONCE(sock_net(sk)->core.sysctl_somaxconn);



	queue->fastopenq.max_qlen = min_t(unsigned int, backlog, somaxconn);

	WRITE_ONCE(queue->fastopenq.max_qlen, min_t(unsigned int, backlog, somaxconn));

}



static inline void tcp_move_syn(struct tcp_sock *tp,

net/ipv4/tcp.c

+1 −1
Original line number Diff line number Diff line
@@ -3623,7 +3623,7 @@ static int do_tcp_getsockopt(struct sock *sk, int level, 
		break;



	case TCP_FASTOPEN:

		val = icsk->icsk_accept_queue.fastopenq.max_qlen;

		val = READ_ONCE(icsk->icsk_accept_queue.fastopenq.max_qlen);

		break;



	case TCP_FASTOPEN_CONNECT:

net/ipv4/tcp_fastopen.c

+4 −2
Original line number Diff line number Diff line
@@ -312,6 +312,7 @@ static struct sock *tcp_fastopen_create_child(struct sock *sk, 
static bool tcp_fastopen_queue_check(struct sock *sk)

{

	struct fastopen_queue *fastopenq;

	int max_qlen;



	/* Make sure the listener has enabled fastopen, and we don't

	 * exceed the max # of pending TFO requests allowed before trying
@@ -324,10 +325,11 @@ static bool tcp_fastopen_queue_check(struct sock *sk) 
	 * temporarily vs a server not supporting Fast Open at all.

	 */

	fastopenq = &inet_csk(sk)->icsk_accept_queue.fastopenq;

	if (fastopenq->max_qlen == 0)

	max_qlen = READ_ONCE(fastopenq->max_qlen);

	if (max_qlen == 0)

		return false;



	if (fastopenq->qlen >= fastopenq->max_qlen) {

	if (fastopenq->qlen >= max_qlen) {

		struct request_sock *req1;

		spin_lock(&fastopenq->lock);

		req1 = fastopenq->rskq_rst_head;