netdev - Re: [RFC PATCH 1/2] af_packet: direct dma for packet ineterface

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Message-ID: <CAAsGZS7HF3cvJ5e45tGHRJhU3xJHnSb4jJV8JEG_eKCcV8hEoQ@mail.gmail.com>
Date:   Mon, 6 Mar 2017 13:28:02 -0800
From:   chetan loke <loke.chetan@...il.com>
To:     John Fastabend <john.fastabend@...il.com>
Cc:     Willem de Bruijn <willemdebruijn.kernel@...il.com>,
        Jesper Dangaard Brouer <brouer@...hat.com>,
        bjorn.topel@...il.com, jasowang@...hat.com, ast@...com,
        alexander.duyck@...il.com, john.r.fastabend@...el.com,
        Network Development <netdev@...r.kernel.org>
Subject: Re: [RFC PATCH 1/2] af_packet: direct dma for packet ineterface

On Tue, Jan 31, 2017 at 9:09 PM, John Fastabend
<john.fastabend@...il.com> wrote:

>> If I understand correctly, the difficulty lies in v3 requiring that the
>> timer "close" the block when the timer expires. That may not be worth
>> implementing, indeed.
>>
>
> Yep that is where I just gave up and decided it wasn't worth it.
>

Without a support for timeout, when a user-space app has to do its own
book-keeping or lets say  - shutdown for maintenance/upgrade, then how
can they(app) unblock from this operation? Because if the link is idle
then the DMA may never happen because there are no frames on the wire.
So is there a way to handle this?

Chetan