netdev - Re: [PATCH net-next 02/13] sk_buff: add skb extension infrastructure

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Message-ID: <20181213110347.2lopxrbmseiuum7n@breakpoint.cc>
Date:   Thu, 13 Dec 2018 12:03:47 +0100
From:   Florian Westphal <fw@...len.de>
To:     Eric Dumazet <eric.dumazet@...il.com>
Cc:     Florian Westphal <fw@...len.de>, netdev@...r.kernel.org,
        cpaasch@...le.com, peter.krystad@...el.com,
        mathew.j.martineau@...ux.intel.com
Subject: Re: [PATCH net-next 02/13] sk_buff: add skb extension infrastructure

Eric Dumazet <eric.dumazet@...il.com> wrote:
> 
> 
> On 12/13/2018 02:39 AM, Florian Westphal wrote:
> >
> > Thats whats done in the MPTCP out-of-tree implementation, but I don't
> > think its needed.
> > 
> > It could just delete the extension before ->queue_xmit() AFAIU.
> 
> So, cloning would do an refcount_inc(), and deleting the extension would do an refcount_dec_and_test() ?
> 
> That is what I called an extra pair of atomic operations.

If it replaces 1:1 current mptcp skb->private out-of-tree storage, then
yes.