Re: [PATCH net-next v2 07/12] net: vxlan: add skb drop reasons to vxlan_rcv()

[Alexander Lobakin <aleksander.lobakin@intel.com>]

From: Menglong Dong <menglong8.dong@gmail.com>
Date: Sun, 1 Sep 2024 21:02:17 +0800

> On Fri, Aug 30, 2024 at 11:04 PM Alexander Lobakin
> <aleksander.lobakin@intel.com> wrote:

[...]

>>> @@ -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.
>>
> 
> It can be 0 here, as we don't set a reason for every "goto drop"
> path. For example, in the line:
> 
>     if (!vs)
>         goto drop;
> 
> we don't set a reason, and the "reason" is 0 when we "goto drop",
> as I don't think that it is worth introducing a reason here.

Aaah okay, I didn't notice that, thanks for the explanation!

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

Thanks,
Olek