netdev - Re: [PATCH wpan/next v3 5/9] net: mac802154: Drop IEEE802154_HW_RX_DROP_BAD

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Message-ID: <20220921174932.37f2938f@xps-13>
Date:   Wed, 21 Sep 2022 17:49:32 +0200
From:   Miquel Raynal <miquel.raynal@...tlin.com>
To:     Alexander Aring <aahringo@...hat.com>
Cc:     Alexander Aring <alex.aring@...il.com>,
        Stefan Schmidt <stefan@...enfreihafen.org>,
        linux-wpan@...r.kernel.org,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Eric Dumazet <edumazet@...gle.com>, netdev@...r.kernel.org,
        David Girault <david.girault@...vo.com>,
        Romuald Despres <romuald.despres@...vo.com>,
        Frederic Blain <frederic.blain@...vo.com>,
        Nicolas Schodet <nico@...fr.eu.org>,
        Thomas Petazzoni <thomas.petazzoni@...tlin.com>
Subject: Re: [PATCH wpan/next v3 5/9] net: mac802154: Drop
 IEEE802154_HW_RX_DROP_BAD_CKSUM

Hi Alexander,

aahringo@...hat.com wrote on Thu, 8 Sep 2022 20:49:36 -0400:

> Hi,
> 
> On Mon, Sep 5, 2022 at 4:34 PM Miquel Raynal <miquel.raynal@...tlin.com> wrote:
> >
> > This IEEE802154_HW_RX_DROP_BAD_CKSUM flag was only used by hwsim to
> > reflect the fact that it would not validate the checksum (FCS). In other
> > words, the filtering level of hwsim is always "NONE" while the core
> > expects it to be higher.
> >
> > Now that we have access to real filtering levels, we can actually use
> > them and always enforce the "NONE" level in hwsim. This case is already
> > correctly handled in the receive so we can drop the flag.
> >  
> 
> I would say the whole hwsim driver currently only works because we
> don't transmit wrong frames on a virtual hardware... However this can
> be improved, yes. In my opinion the hwsim driver should pretend to
> work like other transceivers sending frames to mac802154. That means
> the filtering level should be implemented in hwsim not in mac802154 as
> on real hardware the hardware would do filtering.
> 
> I think you should assume for now the previous behaviour that hwsim
> does not send bad frames out. Of course there is a bug but it was
> already there before, but the fix would be to change hwsim driver.

Well, somehow I already implemented all the filtering by software in
one of the other patches. I now agree that it was not relevant (because
of the AACK issue you raised), but instead of fully dropping this code
I might just move it to hwsim because there it would perfectly make
sense?

Thanks,
Miquèl