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Message-ID: <542C3677.5020505@cogentembedded.com>
Date: Wed, 01 Oct 2014 21:14:31 +0400
From: Sergei Shtylyov <sergei.shtylyov@...entembedded.com>
To: Rick Jones <raj@...dy.usa.hp.com>, netdev@...r.kernel.org
CC: davem@...emloft.net
Subject: Re: [PATCH net-next] udp: increment UDP_NO_PORTS when dropping unmatched
multicasts
Hello.
On 10/01/2014 07:19 PM, Rick Jones wrote:
> From: Rick Jones <rick.jones2@...com>
> When there is absolutely no match for an incoming UDP multicast we
> should increment a suitable UDP statistic in addition to the kfree_skb().
> When there were some matches, we should not and simply call consume_skb().
> Signed-off-by: Rick Jones <rick.jones2@...com>
> ---
> Noticed __udp4_lib_mcast_deliver showing-up in a perf dropped packet
> profile on a system sitting on a network with a bunch of Windows boxes
> sending what they are fond of sending.
> Verified that UDP_MIB_NOPORTS increments when it was not before and hit
> the system with a bit of netperf multicast UDP_RR but that is the extent
> of the testing performed.
> diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
> index cd0db54..376e3d3 100644
> --- a/net/ipv4/udp.c
> +++ b/net/ipv4/udp.c
> @@ -1656,6 +1656,7 @@ static int __udp4_lib_mcast_deliver(struct net *net, struct sk_buff *skb,
> int dif = skb->dev->ifindex;
> unsigned int count = 0, offset = offsetof(typeof(*sk), sk_nulls_node);
> unsigned int hash2 = 0, hash2_any = 0, use_hash2 = (hslot->count > 10);
> + unsigned int inner_flushed = 0;
>
> if (use_hash2) {
> hash2_any = udp4_portaddr_hash(net, htonl(INADDR_ANY), hnum) &
> @@ -1694,8 +1695,12 @@ start_lookup:
> */
> if (count) {
> flush_stack(stack, count, skb, count - 1);
> - } else {
> + } else if (!inner_flushed) {
I don't see where this new variable is changed. It's always 0 here.
> + UDP_INC_STATS_BH(net, UDP_MIB_NOPORTS, 0);
> kfree_skb(skb);
> + } else {
> + /* there were matches flushed in the for_each */
> + consume_skb(skb);
> }
> return 0;
> }
WBR, Sergei
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