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From: Tamaki Yanagawa <ty@000ty.net>
To: fw@strlen.de
Cc: netfilter-devel@vger.kernel.org, pablo@netfilter.org,
	phil@nwl.cc, coreteam@netfilter.org,
	linux-kernel@vger.kernel.org, ty@000ty.net
Subject: Re: [PATCH nf] netfilter: nfnetlink_queue: unclone skb before writing NFQA_L2HDR
Date: Sat, 07 Nov 2026 16:32:27 +0000	[thread overview]
Message-ID: <20261107163218.1660-1-ty@000ty.net> (raw)
In-Reply-To: <au9O_KyLej8ckT5V@strlen.de>

Florian Westphal <fw@strlen.de> wrote:
> Can you explain in changelog why full unclone is needed rather than
> skb_ensure_writable()?

It isn't. At the bridge hooks skb->data points to the network header, so
the mac header is in the headroom, and skb_clone_writable() already
checks headroom against hdr_len. skb_ensure_writable(skb, 0) is enough
and also avoids copying clones that own their header area. I'll send a
v2 using it and saying so in the changelog. I re-ran the bridge flood
test with it: the frame on the other port keeps its original header.

Thanks,
Tamaki


      reply	other threads:[~2026-11-07 16:32 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-11-07 16:05 Tamaki Yanagawa
2026-11-07 16:17 ` Florian Westphal
2026-11-07 16:32   ` Tamaki Yanagawa [this message]

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