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net: use skb_queue_empty_lockless() in busy poll contexts

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[ Upstream commit 3f926af3f4 ]

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 <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Eric Dumazet 2019-10-23 22:44:51 -07:00 committed by Greg Kroah-Hartman
parent eaf548feaa
commit 4f3df7f1ea
5 changed files with 5 additions and 5 deletions
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2
drivers/crypto/chelsio/chtls/chtls_io.c
View file

@ -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);

2
net/core/datagram.c
View file

@ -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;

2
net/core/sock.c
View file

@ -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);

2
net/ipv4/tcp.c
View file

@ -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);

2
net/sctp/socket.c
View file

@ -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;
}