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tcp: annotate data-races around fastopenq.max_qlen

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This field can be read locklessly.

Fixes: 1536e2857b ("tcp: Add a TCP_FASTOPEN socket option to get a max backlog on its listner")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Link: https://lore.kernel.org/r/20230719212857.3943972-12-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Eric Dumazet 2023-07-19 21:28:57 +00:00 committed by Jakub Kicinski
parent 26023e91e1
commit 70f360dd70
3 changed files with 6 additions and 4 deletions
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2
include/linux/tcp.h
View File

@ -513,7 +513,7 @@ 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,

2
net/ipv4/tcp.c
View File

@ -4145,7 +4145,7 @@ 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:

6
net/ipv4/tcp_fastopen.c
View File

@ -296,6 +296,7 @@ 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
@ -308,10 +309,11 @@ 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;