diff options
| author |   Eric Dumazet <edumazet@google.com> | 2021-11-15 11:02:43 -0800 |
|---|---|---|
| committer |   David S. Miller <davem@davemloft.net> | 2021-11-16 13:10:34 +0000 |
| commit | 7b6a893a5991f5e8a56795155ae86333b03080b7 (patch) | |
| tree | b4b56acb67359121477091e1512aacb6016a570a /net/ipv4/tcp.c | |
| parent | tcp: annotate data-races on tp->segs_in and tp->data_segs_in (diff) | |
| download | linux-dev-7b6a893a5991f5e8a56795155ae86333b03080b7.tar.xz linux-dev-7b6a893a5991f5e8a56795155ae86333b03080b7.zip | |
tcp: annotate races around tp->urg_data
tcp_poll() and tcp_ioctl() are reading tp->urg_data without socket lock
owned.
Also, it is faster to first check tp->urg_data in tcp_poll(),
then tp->urg_seq == tp->copied_seq, because tp->urg_seq is
located in a different/cold cache line.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4/tcp.c')
| -rw-r--r-- | net/ipv4/tcp.c | 17 |
1 files changed, 9 insertions, 8 deletions
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index 267b2b18f048..313cf648c349 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -545,10 +545,11 @@ __poll_t tcp_poll(struct file *file, struct socket *sock, poll_table *wait) if (state != TCP_SYN_SENT && (state != TCP_SYN_RECV || rcu_access_pointer(tp->fastopen_rsk))) { int target = sock_rcvlowat(sk, 0, INT_MAX); + u16 urg_data = READ_ONCE(tp->urg_data); - if (READ_ONCE(tp->urg_seq) == READ_ONCE(tp->copied_seq) && - !sock_flag(sk, SOCK_URGINLINE) && - tp->urg_data) + if (urg_data && + READ_ONCE(tp->urg_seq) == READ_ONCE(tp->copied_seq) && + !sock_flag(sk, SOCK_URGINLINE)) target++; if (tcp_stream_is_readable(sk, target)) @@ -573,7 +574,7 @@ __poll_t tcp_poll(struct file *file, struct socket *sock, poll_table *wait) } else mask |= EPOLLOUT | EPOLLWRNORM; - if (tp->urg_data & TCP_URG_VALID) + if (urg_data & TCP_URG_VALID) mask |= EPOLLPRI; } else if (state == TCP_SYN_SENT && inet_sk(sk)->defer_connect) { /* Active TCP fastopen socket with defer_connect @@ -607,7 +608,7 @@ int tcp_ioctl(struct sock *sk, int cmd, unsigned long arg) unlock_sock_fast(sk, slow); break; case SIOCATMARK: - answ = tp->urg_data && + answ = READ_ONCE(tp->urg_data) && READ_ONCE(tp->urg_seq) == READ_ONCE(tp->copied_seq); break; case SIOCOUTQ: @@ -1465,7 +1466,7 @@ static int tcp_recv_urg(struct sock *sk, struct msghdr *msg, int len, int flags) char c = tp->urg_data; if (!(flags & MSG_PEEK)) - tp->urg_data = TCP_URG_READ; + WRITE_ONCE(tp->urg_data, TCP_URG_READ); /* Read urgent data. */ msg->msg_flags |= MSG_OOB; @@ -2465,7 +2466,7 @@ found_ok_skb: skip_copy: if (tp->urg_data && after(tp->copied_seq, tp->urg_seq)) { - tp->urg_data = 0; + WRITE_ONCE(tp->urg_data, 0); tcp_fast_path_check(sk); } @@ -2959,7 +2960,7 @@ int tcp_disconnect(struct sock *sk, int flags) tcp_clear_xmit_timers(sk); __skb_queue_purge(&sk->sk_receive_queue); WRITE_ONCE(tp->copied_seq, tp->rcv_nxt); - tp->urg_data = 0; + WRITE_ONCE(tp->urg_data, 0); tcp_write_queue_purge(sk); tcp_fastopen_active_disable_ofo_check(sk); skb_rbtree_purge(&tp->out_of_order_queue); |