6.12-stable review patch. If anyone has any objections, please let me know.
------------------
From: Fernando Fernandez Mancera ffmancera@riseup.net
[ Upstream commit 3d501f562f63b290351169e3e9931ffe3d57b2ae ]
This reverts commit 612b1c0dec5bc7367f90fc508448b8d0d7c05414. On a scenario with multiple threads blocking on a recvfrom(), we need to call sock_def_readable() on every __udp_enqueue_schedule_skb() otherwise the threads won't be woken up as __skb_wait_for_more_packets() is using prepare_to_wait_exclusive().
Link: https://bugzilla.redhat.com/2308477 Fixes: 612b1c0dec5b ("udp: avoid calling sock_def_readable() if possible") Signed-off-by: Fernando Fernandez Mancera ffmancera@riseup.net Reviewed-by: Eric Dumazet edumazet@google.com Link: https://patch.msgid.link/20241202155620.1719-1-ffmancera@riseup.net Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- net/ipv4/udp.c | 14 +++----------- 1 file changed, 3 insertions(+), 11 deletions(-)
diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c index 2849b273b1310..ff85242720a0a 100644 --- a/net/ipv4/udp.c +++ b/net/ipv4/udp.c @@ -1516,7 +1516,6 @@ int __udp_enqueue_schedule_skb(struct sock *sk, struct sk_buff *skb) struct sk_buff_head *list = &sk->sk_receive_queue; int rmem, err = -ENOMEM; spinlock_t *busy = NULL; - bool becomes_readable; int size, rcvbuf;
/* Immediately drop when the receive queue is full. @@ -1557,19 +1556,12 @@ int __udp_enqueue_schedule_skb(struct sock *sk, struct sk_buff *skb) */ sock_skb_set_dropcount(sk, skb);
- becomes_readable = skb_queue_empty(list); __skb_queue_tail(list, skb); spin_unlock(&list->lock);
- if (!sock_flag(sk, SOCK_DEAD)) { - if (becomes_readable || - sk->sk_data_ready != sock_def_readable || - READ_ONCE(sk->sk_peek_off) >= 0) - INDIRECT_CALL_1(sk->sk_data_ready, - sock_def_readable, sk); - else - sk_wake_async_rcu(sk, SOCK_WAKE_WAITD, POLL_IN); - } + if (!sock_flag(sk, SOCK_DEAD)) + INDIRECT_CALL_1(sk->sk_data_ready, sock_def_readable, sk); + busylock_release(busy); return 0;