Commit 363dc73a authored by Paolo Abeni's avatar Paolo Abeni Committed by David S. Miller

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
...@@ -1205,14 +1205,14 @@ int __udp_enqueue_schedule_skb(struct sock *sk, struct sk_buff *skb) ...@@ -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 * queue is full; always allow at least a packet
*/ */
rmem = atomic_read(&sk->sk_rmem_alloc); rmem = atomic_read(&sk->sk_rmem_alloc);
if (rmem && (rmem + size > sk->sk_rcvbuf)) if (rmem > sk->sk_rcvbuf)
goto drop; goto drop;
/* we drop only if the receive buf is full and the receive /* we drop only if the receive buf is full and the receive
* queue contains some other skb * queue contains some other skb
*/ */
rmem = atomic_add_return(size, &sk->sk_rmem_alloc); 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; goto uncharge_drop;
spin_lock(&list->lock); spin_lock(&list->lock);
......
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