netdev - Re: [PATCH net] qmi_wwan: Clone the skb when in pass-through mode

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Message-ID: <871r93w8l9.fsf@miraculix.mork.no>
Date:   Tue, 15 Jun 2021 15:39:14 +0200
From:   Bjørn Mork <bjorn@...k.no>
To:     Kristian Evensen <kristian.evensen@...il.com>
Cc:     Jakub Kicinski <kuba@...nel.org>,
        Network Development <netdev@...r.kernel.org>,
        subashab@...eaurora.org
Subject: Re: [PATCH net] qmi_wwan: Clone the skb when in pass-through mode

Kristian Evensen <kristian.evensen@...il.com> writes:
> On Tue, Jun 15, 2021 at 12:51 PM Kristian Evensen
> <kristian.evensen@...il.com> wrote:
>> I think this would be a really nice solution. The same (at least
>> FLAG_MULTI_PACKET + usbnet_skb_return) could be applied to pass
>> through as well, giving us consistent handling of aggregated packets.
>> While we might not save a huge number of lines, I believe the
>> resulting code will be easier to understand.
>
> Apologies for the noise. When I check the code again, I see that as
> long as FLAG_MULTI_PACKET is set, then we end up with usbnet freeing
> the skb (we will always jump to done in rx_process()). So for the
> pass-through case, I believe your initial suggestion of having
> rx_fixup return 1 is the way to go.

Yes, if we are to use FLAG_MULTI_PACKET then we must call
usbnet_skb_return() for all the non-muxed cases.  There is no clean way
to enable FLAG_MULTI_PACKET on-demand.

I am fine with either solution.  Whatever Jakub wants :-)


Bjørn