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authorEric Dumazet <edumazet@google.com>2019-10-11 06:17:43 +0300
committerDavid S. Miller <davem@davemloft.net>2019-10-13 20:13:08 +0300
commitd9b55bf7b6788ec0bd1db1acefbc4feb1399144a (patch)
tree428615c37202b0d44173735a2efe04651aff469b /net
parente0d694d638dba768b47be31c22e1a9b4f862f561 (diff)
downloadlinux-d9b55bf7b6788ec0bd1db1acefbc4feb1399144a.tar.xz
tcp: annotate tp->urg_seq lockless reads
There two places where we fetch tp->urg_seq while this field can change from IRQ or other cpu. We need to add READ_ONCE() annotations, and also make sure write side use corresponding WRITE_ONCE() to avoid store-tearing. Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net')
-rw-r--r--net/ipv4/tcp.c5
-rw-r--r--net/ipv4/tcp_input.c2
2 files changed, 4 insertions, 3 deletions
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 652568750cb1..577a8c6eef9f 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -546,7 +546,7 @@ __poll_t tcp_poll(struct file *file, struct socket *sock, poll_table *wait)
(state != TCP_SYN_RECV || rcu_access_pointer(tp->fastopen_rsk))) {
int target = sock_rcvlowat(sk, 0, INT_MAX);
- if (tp->urg_seq == READ_ONCE(tp->copied_seq) &&
+ if (READ_ONCE(tp->urg_seq) == READ_ONCE(tp->copied_seq) &&
!sock_flag(sk, SOCK_URGINLINE) &&
tp->urg_data)
target++;
@@ -607,7 +607,8 @@ int tcp_ioctl(struct sock *sk, int cmd, unsigned long arg)
unlock_sock_fast(sk, slow);
break;
case SIOCATMARK:
- answ = tp->urg_data && tp->urg_seq == READ_ONCE(tp->copied_seq);
+ answ = tp->urg_data &&
+ READ_ONCE(tp->urg_seq) == READ_ONCE(tp->copied_seq);
break;
case SIOCOUTQ:
if (sk->sk_state == TCP_LISTEN)
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index a30aae3a6a18..16342e043ab3 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -5356,7 +5356,7 @@ static void tcp_check_urg(struct sock *sk, const struct tcphdr *th)
}
tp->urg_data = TCP_URG_NOTYET;
- tp->urg_seq = ptr;
+ WRITE_ONCE(tp->urg_seq, ptr);
/* Disable header prediction. */
tp->pred_flags = 0;