From 4f3df7f1eaa70903c2c0c73c0999e120fe452a2a Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Wed, 23 Oct 2019 22:44:51 -0700 Subject: [PATCH] net: use skb_queue_empty_lockless() in busy poll contexts [ Upstream commit 3f926af3f4d688e2e11e7f8ed04e277a14d4d4a4 ] Busy polling usually runs without locks. Let's use skb_queue_empty_lockless() instead of skb_queue_empty() Also uses READ_ONCE() in __skb_try_recv_datagram() to address a similar potential problem. Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- drivers/crypto/chelsio/chtls/chtls_io.c | 2 +- net/core/datagram.c | 2 +- net/core/sock.c | 2 +- net/ipv4/tcp.c | 2 +- net/sctp/socket.c | 2 +- 5 files changed, 5 insertions(+), 5 deletions(-) diff --git a/drivers/crypto/chelsio/chtls/chtls_io.c b/drivers/crypto/chelsio/chtls/chtls_io.c index afebbd8..1587f4a 100644 --- a/drivers/crypto/chelsio/chtls/chtls_io.c +++ b/drivers/crypto/chelsio/chtls/chtls_io.c @@ -1716,7 +1716,7 @@ int chtls_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, return peekmsg(sk, msg, len, nonblock, flags); if (sk_can_busy_loop(sk) && - skb_queue_empty(&sk->sk_receive_queue) && + skb_queue_empty_lockless(&sk->sk_receive_queue) && sk->sk_state == TCP_ESTABLISHED) sk_busy_loop(sk, nonblock); diff --git a/net/core/datagram.c b/net/core/datagram.c index b69e0e2..d3b9961 100644 --- a/net/core/datagram.c +++ b/net/core/datagram.c @@ -279,7 +279,7 @@ struct sk_buff *__skb_try_recv_datagram(struct sock *sk, unsigned int flags, break; sk_busy_loop(sk, flags & MSG_DONTWAIT); - } while (sk->sk_receive_queue.prev != *last); + } while (READ_ONCE(sk->sk_receive_queue.prev) != *last); error = -EAGAIN; diff --git a/net/core/sock.c b/net/core/sock.c index 5f652db..6c11078 100644 --- a/net/core/sock.c +++ b/net/core/sock.c @@ -3483,7 +3483,7 @@ bool sk_busy_loop_end(void *p, unsigned long start_time) { struct sock *sk = p; - return !skb_queue_empty(&sk->sk_receive_queue) || + return !skb_queue_empty_lockless(&sk->sk_receive_queue) || sk_busy_loop_timeout(sk, start_time); } EXPORT_SYMBOL(sk_busy_loop_end); diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index 0e7bcc0..647ba44 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -1948,7 +1948,7 @@ int tcp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, int nonblock, if (unlikely(flags & MSG_ERRQUEUE)) return inet_recv_error(sk, msg, len, addr_len); - if (sk_can_busy_loop(sk) && skb_queue_empty(&sk->sk_receive_queue) && + if (sk_can_busy_loop(sk) && skb_queue_empty_lockless(&sk->sk_receive_queue) && (sk->sk_state == TCP_ESTABLISHED)) sk_busy_loop(sk, nonblock); diff --git a/net/sctp/socket.c b/net/sctp/socket.c index d922c78..c766315 100644 --- a/net/sctp/socket.c +++ b/net/sctp/socket.c @@ -8334,7 +8334,7 @@ struct sk_buff *sctp_skb_recv_datagram(struct sock *sk, int flags, if (sk_can_busy_loop(sk)) { sk_busy_loop(sk, noblock); - if (!skb_queue_empty(&sk->sk_receive_queue)) + if (!skb_queue_empty_lockless(&sk->sk_receive_queue)) continue; } -- 2.7.4