netdev - Re: [PATCH net-next v4 1/2] net: mhi-net: Add de-aggeration support

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Date:   Thu, 4 Feb 2021 09:01:23 +0100
From:   Loic Poulain <loic.poulain@...aro.org>
To:     Jesse Brandeburg <jesse.brandeburg@...el.com>
Cc:     Jakub Kicinski <kuba@...nel.org>,
        David Miller <davem@...emloft.net>,
        Willem de Bruijn <willemdebruijn.kernel@...il.com>,
        Network Development <netdev@...r.kernel.org>,
        Sean Tranchetti <stranche@...eaurora.org>,
        Subash Abhinov Kasiviswanathan <subashab@...eaurora.org>
Subject: Re: [PATCH net-next v4 1/2] net: mhi-net: Add de-aggeration support

Hi Jesse,

On Thu, 4 Feb 2021 at 00:16, Jesse Brandeburg
<jesse.brandeburg@...el.com> wrote:
>
> Loic Poulain wrote:
>
> > When device side MTU is larger than host side MTU, the packets
> > (typically rmnet packets) are split over multiple MHI transfers.
> > In that case, fragments must be re-aggregated to recover the packet
> > before forwarding to upper layer.
> >
> > A fragmented packet result in -EOVERFLOW MHI transaction status for
> > each of its fragments, except the final one. Such transfer was
> > previously considered as error and fragments were simply dropped.
> >
> > This change adds re-aggregation mechanism using skb chaining, via
> > skb frag_list.
> >
> > A warning (once) is printed since this behavior usually comes from
> > a misconfiguration of the device (e.g. modem MTU).
> >
> > Signed-off-by: Loic Poulain <loic.poulain@...aro.org>
> > ---
> >  v2: use zero-copy skb chaining instead of skb_copy_expand.
> >  v3: Fix nit in commit msg + remove misleading inline comment for frag_list
> >  v4: no change
>
> apologies for the nit, can you please fix the spelling of aggregation in
> the subject?

I will, anyway I need to change that since it is not de-aggregation
but re-aggregation of fragmented packets.

Thanks
Loic