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Commit 4f3df7f1 authored by Eric Dumazet's avatar Eric Dumazet Committed by Greg Kroah-Hartman
Browse files

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: default avatarEric Dumazet <edumazet@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent eaf548fe

drivers/crypto/chelsio/chtls/chtls_io.c

+1 −1
Original line number Diff line number Diff line
@@ -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);

net/core/datagram.c

+1 −1
Original line number Diff line number Diff line
@@ -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;

net/core/sock.c

+1 −1
Original line number Diff line number Diff line
@@ -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);

net/ipv4/tcp.c

+1 −1
Original line number Diff line number Diff line
@@ -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);

net/sctp/socket.c

+1 −1
Original line number Diff line number Diff line
@@ -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;

		}