tcp: annotate lockless access to sk->sk_err

tcp_poll() reads sk->sk_err without socket lock held/owned.

We should used READ_ONCE() here, and update writers
to use WRITE_ONCE().

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 288693981b0060c028680033aee143466b2285e4..01569de651b65aa5641fb0c06e0fb81dc40cd85a 100644 (file)
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -589,7 +589,8 @@ __poll_t tcp_poll(struct file *file, struct socket *sock, poll_table *wait)
        }
        /* This barrier is coupled with smp_wmb() in tcp_reset() */
        smp_rmb();
-       if (sk->sk_err || !skb_queue_empty_lockless(&sk->sk_error_queue))
+       if (READ_ONCE(sk->sk_err) ||
+           !skb_queue_empty_lockless(&sk->sk_error_queue))
                mask |= EPOLLERR;
 
        return mask;
@@ -3094,7 +3095,7 @@ int tcp_disconnect(struct sock *sk, int flags)
        if (old_state == TCP_LISTEN) {
                inet_csk_listen_stop(sk);
        } else if (unlikely(tp->repair)) {
-               sk->sk_err = ECONNABORTED;
+               WRITE_ONCE(sk->sk_err, ECONNABORTED);
        } else if (tcp_need_reset(old_state) ||
                   (tp->snd_nxt != tp->write_seq &&
                    (1 << old_state) & (TCPF_CLOSING | TCPF_LAST_ACK))) {
@@ -3102,9 +3103,9 @@ int tcp_disconnect(struct sock *sk, int flags)
                 * states
                 */
                tcp_send_active_reset(sk, gfp_any());
-               sk->sk_err = ECONNRESET;
+               WRITE_ONCE(sk->sk_err, ECONNRESET);
        } else if (old_state == TCP_SYN_SENT)
-               sk->sk_err = ECONNRESET;
+               WRITE_ONCE(sk->sk_err, ECONNRESET);
 
        tcp_clear_xmit_timers(sk);
        __skb_queue_purge(&sk->sk_receive_queue);
@@ -4692,7 +4693,7 @@ int tcp_abort(struct sock *sk, int err)
        bh_lock_sock(sk);
 
        if (!sock_flag(sk, SOCK_DEAD)) {
-               sk->sk_err = err;
+               WRITE_ONCE(sk->sk_err, err);
                /* This barrier is coupled with smp_rmb() in tcp_poll() */
                smp_wmb();
                sk_error_report(sk);

diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 8b5b6ca6617d0f6e2b03cf7164a6e8929fc521e1..754ddbe0577f139d209032b4f15787392fe9a1d5 100644 (file)
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -4322,15 +4322,15 @@ void tcp_reset(struct sock *sk, struct sk_buff *skb)
        /* We want the right error as BSD sees it (and indeed as we do). */
        switch (sk->sk_state) {
        case TCP_SYN_SENT:
-               sk->sk_err = ECONNREFUSED;
+               WRITE_ONCE(sk->sk_err, ECONNREFUSED);
                break;
        case TCP_CLOSE_WAIT:
-               sk->sk_err = EPIPE;
+               WRITE_ONCE(sk->sk_err, EPIPE);
                break;
        case TCP_CLOSE:
                return;
        default:
-               sk->sk_err = ECONNRESET;
+               WRITE_ONCE(sk->sk_err, ECONNRESET);
        }
        /* This barrier is coupled with smp_rmb() in tcp_poll() */
        smp_wmb();

diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 4f6894469b620a75963b9329fc9944d835671515..89daa6b953ff4c49284959b2500618a963685d7d 100644 (file)
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -596,7 +596,7 @@ int tcp_v4_err(struct sk_buff *skb, u32 info)
                ip_icmp_error(sk, skb, err, th->dest, info, (u8 *)th);
 
                if (!sock_owned_by_user(sk)) {
-                       sk->sk_err = err;
+                       WRITE_ONCE(sk->sk_err, err);
 
                        sk_error_report(sk);
 
@@ -625,7 +625,7 @@ int tcp_v4_err(struct sk_buff *skb, u32 info)
 
        inet = inet_sk(sk);
        if (!sock_owned_by_user(sk) && inet->recverr) {
-               sk->sk_err = err;
+               WRITE_ONCE(sk->sk_err, err);
                sk_error_report(sk);
        } else  { /* Only an error on timeout */
                WRITE_ONCE(sk->sk_err_soft, err);

diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 71d01cf3c13eb4bd3d314ef140568d2ffd6a499e..f7e00d90a7304cdbaee493d994c6ab1063392d34 100644 (file)
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -3699,7 +3699,7 @@ static void tcp_connect_init(struct sock *sk)
        tp->rx_opt.rcv_wscale = rcv_wscale;
        tp->rcv_ssthresh = tp->rcv_wnd;
 
-       sk->sk_err = 0;
+       WRITE_ONCE(sk->sk_err, 0);
        sock_reset_flag(sk, SOCK_DONE);
        tp->snd_wnd = 0;
        tcp_init_wl(tp, 0);

diff --git a/net/ipv4/tcp_timer.c b/net/ipv4/tcp_timer.c
index 8823e2182713a26fa42ce44a21b9ec7a4d7e1c73..b839c2f91292f7346f33d6dcbf597594473a5aca 100644 (file)
--- a/net/ipv4/tcp_timer.c
+++ b/net/ipv4/tcp_timer.c
@@ -67,7 +67,7 @@ u32 tcp_clamp_probe0_to_user_timeout(const struct sock *sk, u32 when)
 
 static void tcp_write_err(struct sock *sk)
 {
-       sk->sk_err = READ_ONCE(sk->sk_err_soft) ? : ETIMEDOUT;
+       WRITE_ONCE(sk->sk_err, READ_ONCE(sk->sk_err_soft) ? : ETIMEDOUT);
        sk_error_report(sk);
 
        tcp_write_queue_purge(sk);

diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index dc963eebc668f7d24981de21650608a27e431d41..35cf523c9efd4370bf3110f6777592eabb15ca9e 100644 (file)
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -493,7 +493,7 @@ static int tcp_v6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
                ipv6_icmp_error(sk, skb, err, th->dest, ntohl(info), (u8 *)th);
 
                if (!sock_owned_by_user(sk)) {
-                       sk->sk_err = err;
+                       WRITE_ONCE(sk->sk_err, err);
                        sk_error_report(sk);            /* Wake people up to see the error (see connect in sock.c) */
 
                        tcp_done(sk);
@@ -513,7 +513,7 @@ static int tcp_v6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
        }
 
        if (!sock_owned_by_user(sk) && np->recverr) {
-               sk->sk_err = err;
+               WRITE_ONCE(sk->sk_err, err);
                sk_error_report(sk);
        } else {
                WRITE_ONCE(sk->sk_err_soft, err);