Commit 6a1f12dd authored by Eric Dumazet's avatar Eric Dumazet Committed by Jakub Kicinski
Browse files

udp: relax atomic operation on sk->sk_rmem_alloc 



atomic_add_return() is more expensive than atomic_add()
and seems overkill in UDP rx fast path.

Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Link: https://lore.kernel.org/r/20240328144032.1864988-3-edumazet@google.com


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent 60557969

net/ipv4/udp.c

+1 −6
Original line number Diff line number Diff line
@@ -1516,12 +1516,7 @@ int __udp_enqueue_schedule_skb(struct sock *sk, struct sk_buff *skb) 
	size = skb->truesize;

	udp_set_dev_scratch(skb);



	/* we drop only if the receive buf is full and the receive

	 * queue contains some other skb

	 */

	rmem = atomic_add_return(size, &sk->sk_rmem_alloc);

	if (rmem > (size + (unsigned int)sk->sk_rcvbuf))

		goto uncharge_drop;

	atomic_add(size, &sk->sk_rmem_alloc);



	spin_lock(&list->lock);

	err = udp_rmem_schedule(sk, size);