Before commit 850cbaddb52d ("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: Jesper Dangaard Brouer <bro...@redhat.com>
Fixes: 850cbaddb52d ("udp: use it's own memory accounting schema")
Signed-off-by: Paolo Abeni <pab...@redhat.com>
---
net/ipv4/udp.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index e1d0bf8..16d88ba 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -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);
--
1.8.3.1
