linux-kernel - Re: [PATCH net-next v2 07/12] net: vxlan: add skb drop reasons to vxlan

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Message-ID: <c5896f81-5c32-43f0-8641-81fdb4710a4b@intel.com>
Date: Fri, 30 Aug 2024 17:04:10 +0200
From: Alexander Lobakin <aleksander.lobakin@...el.com>
To: Menglong Dong <menglong8.dong@...il.com>
CC: <idosch@...dia.com>, <kuba@...nel.org>, <davem@...emloft.net>,
	<edumazet@...gle.com>, <pabeni@...hat.com>, <dsahern@...nel.org>,
	<dongml2@...natelecom.cn>, <amcohen@...dia.com>, <gnault@...hat.com>,
	<bpoirier@...dia.com>, <b.galvani@...il.com>, <razor@...ckwall.org>,
	<petrm@...dia.com>, <linux-kernel@...r.kernel.org>, <netdev@...r.kernel.org>
Subject: Re: [PATCH net-next v2 07/12] net: vxlan: add skb drop reasons to
 vxlan_rcv()

From: Menglong Dong <menglong8.dong@...il.com>
Date: Fri, 30 Aug 2024 09:59:56 +0800

> Introduce skb drop reasons to the function vxlan_rcv(). Following new
> vxlan drop reasons are added:
> 
>   VXLAN_DROP_INVALID_HDR
>   VXLAN_DROP_VNI_NOT_FOUND
> 
> And Following core skb drop reason is added:

"the following", lowercase + "the".

> 
>   SKB_DROP_REASON_IP_TUNNEL_ECN
> 
> Signed-off-by: Menglong Dong <dongml2@...natelecom.cn>

[...]

> @@ -23,6 +25,14 @@ enum vxlan_drop_reason {
>  	 * one pointing to a nexthop
>  	 */
>  	VXLAN_DROP_ENTRY_EXISTS,
> +	/**
> +	 * @VXLAN_DROP_INVALID_HDR: the vxlan header is invalid, such as:

Same as before, "VXLAN" in uppercase I'd say.

> +	 * 1) the reserved fields are not zero
> +	 * 2) the "I" flag is not set
> +	 */
> +	VXLAN_DROP_INVALID_HDR,
> +	/** @VXLAN_DROP_VNI_NOT_FOUND: no vxlan device found for the vni */

^

> +	VXLAN_DROP_VNI_NOT_FOUND,
>  };

[...]

>  	if (!raw_proto) {
> -		if (!vxlan_set_mac(vxlan, vs, skb, vni))
> +		reason = vxlan_set_mac(vxlan, vs, skb, vni);
> +		if (reason)
>  			goto drop;

This piece must go in the previous patch, see my comment there.

[...]

> @@ -1814,8 +1830,9 @@ static int vxlan_rcv(struct sock *sk, struct sk_buff *skb)
>  	return 0;
>  
>  drop:
> +	reason = reason ?: SKB_DROP_REASON_NOT_SPECIFIED;

Is this possible that @reason will be 0 (NOT_DROPPED_YET) here? At the
beginning of the function, it's not initialized, then each error path
sets it to a specific value. In most paths, you check for it being != 0
as a sign of error, so I doubt it can be 0 here.

>  	/* Consume bad packet */
> -	kfree_skb(skb);
> +	kfree_skb_reason(skb, reason);
>  	return 0;
>  }

Thanks,
Olek