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Message-ID: <2969b15c-b825-3b0e-2ad7-00633ee6815b@kernel.org>
Date:   Mon, 21 Feb 2022 20:17:01 -0700
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Subject: Re: [PATCH net-next 2/3] net: neigh: use kfree_skb_reason() for
 __neigh_event_send()
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To:     menglong8.dong@gmail.com, kuba@kernel.org
Cc:     rostedt@goodmis.org, mingo@redhat.com, davem@davemloft.net,
        yoshfuji@linux-ipv6.org, imagedong@tencent.com,
        edumazet@google.com, alobakin@pm.me, cong.wang@bytedance.com,
        paulb@nvidia.com, talalahmad@google.com, keescook@chromium.org,
        ilias.apalodimas@linaro.org, memxor@gmail.com,
        flyingpeng@tencent.com, mengensun@tencent.com,
        daniel@iogearbox.net, yajun.deng@linux.dev, roopa@nvidia.com,
        linux-kernel@vger.kernel.org, netdev@vger.kernel.org
References: <20220220155705.194266-1-imagedong@tencent.com>
 <20220220155705.194266-3-imagedong@tencent.com>
From:   David Ahern <dsahern@kernel.org>
In-Reply-To: <20220220155705.194266-3-imagedong@tencent.com>
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On 2/20/22 8:57 AM, menglong8.dong@gmail.com wrote:
> diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
> index c310a4a8fc86..206b66f5ce6b 100644
> --- a/include/linux/skbuff.h
> +++ b/include/linux/skbuff.h
> @@ -393,6 +393,15 @@ enum skb_drop_reason {
>  					 * see the doc for disable_ipv6
>  					 * in ip-sysctl.rst for detail
>  					 */
> +	SKB_DROP_REASON_NEIGH_FAILED,	/* dropped as the state of
> +					 * neighbour is NUD_FAILED
> +					 */

/* neigh entry in failed state */

> +	SKB_DROP_REASON_NEIGH_QUEUEFULL,	/* the skbs that waiting
> +						 * for sending on the queue
> +						 * of neigh->arp_queue is
> +						 * full, and the skbs on the
> +						 * tail will be dropped
> +						 */

/* arp_queue for neigh entry is full */


> diff --git a/net/core/neighbour.c b/net/core/neighbour.c
> index ec0bf737b076..c353834e8fa9 100644
> --- a/net/core/neighbour.c
> +++ b/net/core/neighbour.c
> @@ -1171,7 +1171,7 @@ int __neigh_event_send(struct neighbour *neigh, struct sk_buff *skb,
>  			neigh->updated = jiffies;
>  			write_unlock_bh(&neigh->lock);
>  
> -			kfree_skb(skb);
> +			kfree_skb_reason(skb, SKB_DROP_REASON_NEIGH_FAILED);
>  			return 1;
>  		}
>  	} else if (neigh->nud_state & NUD_STALE) {
> @@ -1193,7 +1193,7 @@ int __neigh_event_send(struct neighbour *neigh, struct sk_buff *skb,
>  				if (!buff)
>  					break;
>  				neigh->arp_queue_len_bytes -= buff->truesize;
> -				kfree_skb(buff);
> +				kfree_skb_reason(buff, SKB_DROP_REASON_NEIGH_QUEUEFULL);
>  				NEIGH_CACHE_STAT_INC(neigh->tbl, unres_discards);
>  			}
>  			skb_dst_force(skb);

what about out_dead: path? the tracepoint there shows that path is of
interest.