From 63c3c44ff4c535157e7574452c9f37d93dafdd20 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Tue, 19 Dec 2023 17:00:17 +0000 Subject: [PATCH] sctp: fix busy polling [ Upstream commit a562c0a2d651e040681b0bfce9b4d229ac3b0b8c ] Busy polling while holding the socket lock makes litle sense, because incoming packets wont reach our receive queue. Fixes: 8465a5fcd1ce ("sctp: add support for busy polling to sctp protocol") Reported-by: Jacob Moroni Signed-off-by: Eric Dumazet Cc: Marcelo Ricardo Leitner Cc: Xin Long Signed-off-by: David S. Miller Signed-off-by: Sasha Levin --- net/sctp/socket.c | 10 ++++------ 1 file changed, 4 insertions(+), 6 deletions(-) diff --git a/net/sctp/socket.c b/net/sctp/socket.c index 5fb02bbb4b34..6b9fcdb0952a 100644 --- a/net/sctp/socket.c +++ b/net/sctp/socket.c @@ -2102,6 +2102,10 @@ static int sctp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, if (unlikely(flags & MSG_ERRQUEUE)) return inet_recv_error(sk, msg, len, addr_len); + if (sk_can_busy_loop(sk) && + skb_queue_empty_lockless(&sk->sk_receive_queue)) + sk_busy_loop(sk, flags & MSG_DONTWAIT); + lock_sock(sk); if (sctp_style(sk, TCP) && !sctp_sstate(sk, ESTABLISHED) && @@ -9046,12 +9050,6 @@ struct sk_buff *sctp_skb_recv_datagram(struct sock *sk, int flags, int *err) if (sk->sk_shutdown & RCV_SHUTDOWN) break; - if (sk_can_busy_loop(sk)) { - sk_busy_loop(sk, flags & MSG_DONTWAIT); - - if (!skb_queue_empty_lockless(&sk->sk_receive_queue)) - continue; - } /* User doesn't want to wait. */ error = -EAGAIN;