netdev - Re: [PATCH net] Revert "net: macsec: use skb_ensure_writable_head

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Message-ID: <9b1d136c156b33759a0323e988b73839d5920acc.camel@redhat.com>
Date: Tue, 16 Jan 2024 11:39:35 +0100
From: Paolo Abeni <pabeni@...hat.com>
To: Rahul Rameshbabu <rrameshbabu@...dia.com>, netdev@...r.kernel.org
Cc: Gal Pressman <gal@...dia.com>, Eric Dumazet <edumazet@...gle.com>, Jakub
 Kicinski <kuba@...nel.org>, Radu Pirea <radu-nicolae.pirea@....nxp.com>,
 "David S . Miller" <davem@...emloft.net>, Sabrina Dubroca
 <sd@...asysnail.net>
Subject: Re: [PATCH net] Revert "net: macsec: use
 skb_ensure_writable_head_tail to expand the skb"

On Sun, 2024-01-14 at 09:42 -0800, Rahul Rameshbabu wrote:
> This reverts commit b34ab3527b9622ca4910df24ff5beed5aa66c6b5.
> 
> Using skb_ensure_writable_head_tail without a call to skb_unshare causes
> the MACsec stack to operate on the original skb rather than a copy in the
> macsec_encrypt path. This causes the buffer to be exceeded in space, and
> leads to warnings generated by skb_put operations. 

This part of the changelog is confusing to me. It looks like the skb
should be uncloned under the same conditions before and after this
patch (and/or the reverted)??!

Possibly dev->needed_headroom/needed_tailroom values are incorrect?!?

Thanks!

Paolo