tcp: annotate sk->sk_sndbuf lockless reads
For the sake of tcp_poll(), there are few places where we fetch
sk->sk_sndbuf while this field can change from IRQ or other cpu.
We need to add READ_ONCE() annotations, and also make sure write
sides use corresponding WRITE_ONCE() to avoid store-tearing.
Note that other transports probably need similar fixes.
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 bc0481a..1118532 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -450,7 +450,7 @@ void tcp_init_sock(struct sock *sk)
icsk->icsk_sync_mss = tcp_sync_mss;
- sk->sk_sndbuf = sock_net(sk)->ipv4.sysctl_tcp_wmem[1];
+ WRITE_ONCE(sk->sk_sndbuf, sock_net(sk)->ipv4.sysctl_tcp_wmem[1]);
WRITE_ONCE(sk->sk_rcvbuf, sock_net(sk)->ipv4.sysctl_tcp_rmem[1]);
sk_sockets_allocated_inc(sk);
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 6995df2..a2e52ad 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -359,7 +359,8 @@ static void tcp_sndbuf_expand(struct sock *sk)
sndmem *= nr_segs * per_mss;
if (sk->sk_sndbuf < sndmem)
- sk->sk_sndbuf = min(sndmem, sock_net(sk)->ipv4.sysctl_tcp_wmem[2]);
+ WRITE_ONCE(sk->sk_sndbuf,
+ min(sndmem, sock_net(sk)->ipv4.sysctl_tcp_wmem[2]));
}
/* 2. Tuning advertised window (window_clamp, rcv_ssthresh)