netdev - Re: [PATCH net-next RFC v1 0/3] net: sched: refactor qdisc drop reasons into dedicated tracepoint

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <41da26a6-4024-461f-8254-ac5dcf231397@kernel.org>
Date: Fri, 6 Feb 2026 15:41:23 +0100
From: Jesper Dangaard Brouer <hawk@...nel.org>
To: Antoine Tenart <atenart@...hat.com>,
 Toke Høiland-Jørgensen <toke@...hat.com>
Cc: Jakub Kicinski <kuba@...nel.org>, Eric Dumazet <eric.dumazet@...il.com>,
 netdev@...r.kernel.org, "David S. Miller" <davem@...emloft.net>,
 Paolo Abeni <pabeni@...hat.com>, bpf@...r.kernel.org, horms@...nel.org,
 jiri@...nulli.us, edumazet@...gle.com, xiyou.wangcong@...il.com,
 jhs@...atatu.com, carges@...udflare.com, kernel-team@...udflare.com
Subject: Re: [PATCH net-next RFC v1 0/3] net: sched: refactor qdisc drop
 reasons into dedicated tracepoint

On 05/02/2026 17.24, Antoine Tenart wrote:
> On Thu, Feb 05, 2026 at 03:46:29PM +0100, Toke Høiland-Jørgensen wrote:
>> Antoine Tenart <atenart@...hat.com> writes:
>>
>>> I'm wondering why not using the drop reason subsys logic to combine the
>>> qdisc specific enum while not conflicting with drop reasons and allowing
>>> to inject the qdisc reasons into drop reason enabled helpers as well?
>>
>> See this prior discussion for how the proposal came to be:
>>
>> https://lore.kernel.org/all/6be17a08-f8aa-4f91-9bd0-d9e1f0a92d90@kernel.org/
>>
>> Basically, figuring out which qdisc a drop came from is not possible
>> with the current drop_reason code.
>>
>> So it's not just new drop reasons, it's a separate tracepoint with more
>> information available (qdisc handle, name, etc). So you'll get two
>> events for qdisc drops with this series (from patch 1):
>>
>> +		trace_qdisc_drop(q, txq, dev, skb, reason);
>> +		kfree_skb_reason(skb, SKB_DROP_REASON_QDISC_DROP);
> 
> Right and that's fine. Using the drop reason subsys logic you could turn
> the above into:
> 
>   +		trace_qdisc_drop(q, txq, dev, skb, reason);
>   +		kfree_skb_reason(skb, (u32)reason);
> 
> You can look at enum skb_drop_reason_subsys and how that is used within
> OvS (net/openvswitch/drop.h) for example.
> 

Thanks for the input Antoine, I've adapted V2 to use skb_drop_reason_subsys.

Can you point me at the OVS userspace code that consume these subsys 
drop_reason's?

--Jesper
[V2] 
https://lore.kernel.org/all/177032644012.1975497.16411100029657607833.stgit@firesoul/