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Date:   Tue, 8 Mar 2022 15:51:32 -0700
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Subject: Re: [PATCH v3 net-next] net-core: add rx_otherhost_dropped counter
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To:     Jeffrey Ji <jeffreyjilinux@gmail.com>,
        "David S . Miller" <davem@davemloft.net>
Cc:     Brian Vazquez <brianvv@google.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>,
        Eric Dumazet <edumazet@google.com>,
        Antoine Tenart <atenart@kernel.org>,
        Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
        Alexander Lobakin <alexandr.lobakin@intel.com>,
        Kumar Kartikeya Dwivedi <memxor@gmail.com>,
        Arnd Bergmann <arnd@arndb.de>, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org, jeffreyji <jeffreyji@google.com>
References: <20220308212531.752215-1-jeffreyjilinux@gmail.com>
From:   David Ahern <dsahern@kernel.org>
In-Reply-To: <20220308212531.752215-1-jeffreyjilinux@gmail.com>
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On 3/8/22 2:25 PM, Jeffrey Ji wrote:
> diff --git a/net/ipv4/ip_input.c b/net/ipv4/ip_input.c
> index 95f7bb052784..8b87ea99904b 100644
> --- a/net/ipv4/ip_input.c
> +++ b/net/ipv4/ip_input.c
> @@ -451,6 +451,7 @@ static struct sk_buff *ip_rcv_core(struct sk_buff *skb, struct net *net)
>  	 * that it receives, do not try to analyse it.
>  	 */
>  	if (skb->pkt_type == PACKET_OTHERHOST) {
> +		atomic_long_inc(&skb->dev->rx_otherhost_dropped);
>  		drop_reason = SKB_DROP_REASON_OTHERHOST;
>  		goto drop;
>  	}
> diff --git a/net/ipv6/ip6_input.c b/net/ipv6/ip6_input.c
> index 5b5ea35635f9..5624c937f87f 100644
> --- a/net/ipv6/ip6_input.c
> +++ b/net/ipv6/ip6_input.c
> @@ -150,6 +150,7 @@ static struct sk_buff *ip6_rcv_core(struct sk_buff *skb, struct net_device *dev,
>  	struct inet6_dev *idev;
>  
>  	if (skb->pkt_type == PACKET_OTHERHOST) {
> +		atomic_long_inc(&skb->dev->rx_otherhost_dropped);
>  		kfree_skb(skb);
>  		return NULL;
>  	}

that's an expensive packet counter for a common path (e.g., hosting
environments).