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Commit 363dc73a authored by Paolo Abeni's avatar Paolo Abeni Committed by David S. Miller
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udp: be less conservative with sock rmem accounting 



Before commit 850cbadd ("udp: use it's own memory accounting
schema"), the udp protocol allowed sk_rmem_alloc to grow beyond
the rcvbuf by the whole current packet's truesize. After said commit
we allow sk_rmem_alloc to exceed the rcvbuf only if the receive queue
is empty. As reported by Jesper this cause a performance regression
for some (small) values of rcvbuf.

This commit is intended to fix the regression restoring the old
handling of the rcvbuf limit.

Reported-by: default avatarJesper Dangaard Brouer <brouer@redhat.com>
Fixes: 850cbadd ("udp: use it's own memory accounting schema")
Signed-off-by: default avatarPaolo Abeni <pabeni@redhat.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 12efa1fa

net/ipv4/udp.c

+2 −2
Original line number Diff line number Diff line
@@ -1205,14 +1205,14 @@ int __udp_enqueue_schedule_skb(struct sock *sk, struct sk_buff *skb) 
	 * queue is full; always allow at least a packet

	 */

	rmem = atomic_read(&sk->sk_rmem_alloc);

	if (rmem && (rmem + size > sk->sk_rcvbuf))

	if (rmem > sk->sk_rcvbuf)

		goto drop;



	/* 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 > sk->sk_rcvbuf) && (rmem > size))

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

		goto uncharge_drop;



	spin_lock(&list->lock);