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authorEric Dumazet <edumazet@google.com>2023-07-19 21:28:57 +0000
committerJakub Kicinski <kuba@kernel.org>2023-07-20 12:34:18 -0700
commit70f360dd7042cb843635ece9d28335a4addff9eb (patch)
treebc0434cfbd9a1d6ecf48ff10f073e031e60808e9
parent26023e91e12c68669db416b97234328a03d8e499 (diff)
tcp: annotate data-races around fastopenq.max_qlen
This field can be read locklessly. Fixes: 1536e2857bd3 ("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>
-rw-r--r--include/linux/tcp.h2
-rw-r--r--net/ipv4/tcp.c2
-rw-r--r--net/ipv4/tcp_fastopen.c6
3 files changed, 6 insertions, 4 deletions
diff --git a/include/linux/tcp.h b/include/linux/tcp.h
index b4c08ac86983..91a37c99ba66 100644
--- a/include/linux/tcp.h
+++ b/include/linux/tcp.h
@@ -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,
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 3e137e9a18f5..8ed52e1e3c99 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -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:
diff --git a/net/ipv4/tcp_fastopen.c b/net/ipv4/tcp_fastopen.c
index 45cc7f1ca296..85e4953f1182 100644
--- a/net/ipv4/tcp_fastopen.c
+++ b/net/ipv4/tcp_fastopen.c
@@ -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;