netdev - Re: [PATCH net v2 1/2] Revert "net: macsec: use skb_ensure_writable_head

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Message-ID: <87r0i8m2td.fsf@nvidia.com>
Date: Tue, 23 Jan 2024 08:27:04 -0800
From: Rahul Rameshbabu <rrameshbabu@...dia.com>
To: Paolo Abeni <pabeni@...hat.com>
Cc: Sabrina Dubroca <sd@...asysnail.net>, netdev@...r.kernel.org, Gal
 Pressman <gal@...dia.com>, Jakub Kicinski <kuba@...nel.org>, Eric Dumazet
 <edumazet@...gle.com>, Radu Pirea <radu-nicolae.pirea@....nxp.com>, "David
 S . Miller" <davem@...emloft.net>
Subject: Re: [PATCH net v2 1/2] Revert "net: macsec: use
 skb_ensure_writable_head_tail to expand the skb"

On Tue, 23 Jan, 2024 10:19:21 +0100 Paolo Abeni <pabeni@...hat.com> wrote:
> On Sun, 2024-01-21 at 10:32 +0100, Sabrina Dubroca wrote:
>> 2024-01-18, 11:18:06 -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. Opting to revert this
>> > change since skb_copy_expand is more efficient than
>> > skb_ensure_writable_head_tail followed by a call to skb_unshare.
>> 
>> Paolo, are you ok with this commit message? I agree it's a bit
>> confusing but I can't think of anything clearer :(
>
> Yes, I re-read the relevant code and now the fix is clearer to me,
> thanks!

I tried thinking of how to rephrase that description a couple of times
and could not come up with anything better.

>
> I understand the intention is to drop patch 2/2.
>
> Could you please confirm that? If so, I can apply 1/2 without a repost.

Yes, the intention is to drop patch 2/2. It's a "defensive" patch that
does not actually fix any issues from what I can tell.

--
Thanks,

Rahul Rameshbabu