Commit 3d501f56 authored by Fernando Fernandez Mancera's avatar Fernando Fernandez Mancera Committed by Jakub Kicinski
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Revert "udp: avoid calling sock_def_readable() if possible" 

This reverts commit 612b1c0d. 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: 612b1c0d ("udp: avoid calling sock_def_readable() if possible")
Signed-off-by: default avatarFernando Fernandez Mancera <ffmancera@riseup.net>
Reviewed-by: default avatarEric Dumazet <edumazet@google.com>
Link: https://patch.msgid.link/20241202155620.1719-1-ffmancera@riseup.net


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent cecc1555

net/ipv4/udp.c

+3 −11
Original line number Diff line number Diff line
@@ -1674,7 +1674,6 @@ 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.
@@ -1715,19 +1714,12 @@ 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;