netdev - Re: [PATCH net-next v2 1/2] udp: msg

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Message-ID: <ae1b8e52272b14a49ff4225e647c86c0aab57980.camel@redhat.com>
Date:   Mon, 26 Nov 2018 19:04:09 +0100
From:   Paolo Abeni <pabeni@...hat.com>
To:     Willem de Bruijn <willemdebruijn.kernel@...il.com>
Cc:     Network Development <netdev@...r.kernel.org>,
        David Miller <davem@...emloft.net>,
        Willem de Bruijn <willemb@...gle.com>
Subject: Re: [PATCH net-next v2 1/2] udp: msg_zerocopy

On Mon, 2018-11-26 at 12:59 -0500, Willem de Bruijn wrote:
> The callers of this function do flush the queue of the other skbs on
> error, but only after the call to sock_zerocopy_put_abort.
> 
> sock_zerocopy_put_abort depends on total rollback to revert the
> sk_zckey increment and suppress the completion notification (which
> must not happen on return with error).
> 
> I don't immediately have a fix. Need to think about this some more..

[still out of sheer ignorance] How about tacking a refcnt for the whole
ip_append_data() scope, like in the tcp case? that will add an atomic
op per loop (likely, hitting the cache) but will remove some code hunk
in sock_zerocopy_put_abort() and sock_zerocopy_alloc().

Cheer,

Paolo