netdev - Re: [PATCH net 0/6] net/sched: Fix packet loops in mirred and netem

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Message-ID: <d42f0c80-e289-4e0f-8608-10580d315fd9@redhat.com>
Date: Thu, 15 Jan 2026 11:22:57 +0100
From: Paolo Abeni <pabeni@...hat.com>
To: Jamal Hadi Salim <jhs@...atatu.com>, davem@...emloft.net,
 edumazet@...gle.com, kuba@...nel.org, horms@...nel.org, andrew+netdev@...n.ch
Cc: netdev@...r.kernel.org, xiyou.wangcong@...il.com, jiri@...nulli.us,
 victor@...atatu.com, dcaratti@...hat.com, lariel@...dia.com,
 daniel@...earbox.net, pablo@...filter.org, kadlec@...filter.org,
 fw@...len.de, phil@....cc, netfilter-devel@...r.kernel.org,
 coreteam@...filter.org, zyc199902@...omail.cn, lrGerlinde@...lfence.com,
 jschung2@...ton.me
Subject: Re: [PATCH net 0/6] net/sched: Fix packet loops in mirred and netem

On 1/11/26 5:39 PM, Jamal Hadi Salim wrote:
> We introduce a 2-bit global skb->ttl counter.Patch #1 describes how we puti
> together those bits. Patches #2 and patch #5 use these bits.
> I added Fixes tags to patch #1 in case it is useful for backporting.
> Patch #3 and #4 revert William's earlier netem commits. Patch #6 introduces
> tdc test cases.

Generally speaking I think that a more self-encapsulated solution should
be preferable.

I [mis?]understand that your main concern with Cong's series is the
possible parent qlen corruption in case of duplication and the last
iteration of such series includes a self-test for that, is there
anything missing there?

The new sk_buff field looks a bit controversial. Adding such field
opens/implies using it for other/all loop detection; a 2 bits counter
will not be enough for that, and the struct sk_buff will increase for
typical build otherwise.

FTR I don't think that sk_buff the size increase for minimal config is
very relevant, as most/all of the binary layout optimization and not
thought for such build.

/P