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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
2019-11-10 11:25:35 +01:00
committed by Greg Kroah-Hartman
parent 8e7bea4359
commit 0d50fc2bb4
4 changed files with 4 additions and 4 deletions
Download Patch File Download Diff File Expand all files Collapse all files
net/core/datagram.c
+1 -1
View File
@@ -281,7 +281,7 @@ 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;
net/core/sock.c
+1 -1
View File
@@ -3381,7 +3381,7 @@ 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);
net/ipv4/tcp.c
+1 -1
View File
@@ -1787,7 +1787,7 @@ 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);
net/sctp/socket.c
+1 -1
View File
@@ -7716,7 +7716,7 @@ 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;
}