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authorEric Dumazet <edumazet@google.com>2019-10-09 15:32:35 -0700
committerJakub Kicinski <jakub.kicinski@netronome.com>2019-10-09 21:43:00 -0700
commiteac66402d1c342f07ff38f8d631ff95eb7ad3220 (patch)
treed25d4b62d8f9a01ed18b820307bfb0080a26a28f
parent8265792bf8871acc2d00fd03883d830e2249d395 (diff)
net: annotate sk->sk_rcvlowat lockless reads
sock_rcvlowat() or int_sk_rcvlowat() might be called without the socket lock for example from tcp_poll(). Use READ_ONCE() to document the fact that other cpus might change sk->sk_rcvlowat under us and avoid KCSAN splats. Use WRITE_ONCE() on write sides too. Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
-rw-r--r--include/net/sock.h4
-rw-r--r--net/core/filter.c2
-rw-r--r--net/core/sock.c2
-rw-r--r--net/ipv4/tcp.c2
-rw-r--r--net/sched/em_meta.c2
5 files changed, 7 insertions, 5 deletions
diff --git a/include/net/sock.h b/include/net/sock.h
index 2c53f1a1d905..79f54e1f8827 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -2271,7 +2271,9 @@ static inline long sock_sndtimeo(const struct sock *sk, bool noblock)
static inline int sock_rcvlowat(const struct sock *sk, int waitall, int len)
{
- return (waitall ? len : min_t(int, sk->sk_rcvlowat, len)) ? : 1;
+ int v = waitall ? len : min_t(int, READ_ONCE(sk->sk_rcvlowat), len);
+
+ return v ?: 1;
}
/* Alas, with timeout socket operations are not restartable.
diff --git a/net/core/filter.c b/net/core/filter.c
index ed6563622ce3..a50c0b6846f2 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -4274,7 +4274,7 @@ BPF_CALL_5(bpf_setsockopt, struct bpf_sock_ops_kern *, bpf_sock,
case SO_RCVLOWAT:
if (val < 0)
val = INT_MAX;
- sk->sk_rcvlowat = val ? : 1;
+ WRITE_ONCE(sk->sk_rcvlowat, val ? : 1);
break;
case SO_MARK:
if (sk->sk_mark != val) {
diff --git a/net/core/sock.c b/net/core/sock.c
index 1cf06934da50..b7c5c6ea51ba 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -974,7 +974,7 @@ set_rcvbuf:
if (sock->ops->set_rcvlowat)
ret = sock->ops->set_rcvlowat(sk, val);
else
- sk->sk_rcvlowat = val ? : 1;
+ WRITE_ONCE(sk->sk_rcvlowat, val ? : 1);
break;
case SO_RCVTIMEO_OLD:
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 888c92b63f5a..8781a92ea4b6 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -1699,7 +1699,7 @@ int tcp_set_rcvlowat(struct sock *sk, int val)
else
cap = sock_net(sk)->ipv4.sysctl_tcp_rmem[2] >> 1;
val = min(val, cap);
- sk->sk_rcvlowat = val ? : 1;
+ WRITE_ONCE(sk->sk_rcvlowat, val ? : 1);
/* Check if we need to signal EPOLLIN right now */
tcp_data_ready(sk);
diff --git a/net/sched/em_meta.c b/net/sched/em_meta.c
index 82bd14e7ac93..4c9122fc35c9 100644
--- a/net/sched/em_meta.c
+++ b/net/sched/em_meta.c
@@ -554,7 +554,7 @@ META_COLLECTOR(int_sk_rcvlowat)
*err = -1;
return;
}
- dst->value = sk->sk_rcvlowat;
+ dst->value = READ_ONCE(sk->sk_rcvlowat);
}
META_COLLECTOR(int_sk_rcvtimeo)