Message-ID: <CAK-6q+i=biD0pgWsY002PpY_bp3bM56=PdMgqdo5x4bH+JsznA@mail.gmail.com>
Date: Mon, 13 Nov 2023 07:52:25 -0500
From: Alexander Aring <aahringo@...hat.com>
To: Miquel Raynal <miquel.raynal@...tlin.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>, Guilhem Imberton <guilhem.imberton@...vo.com>, 
	Thomas Petazzoni <thomas.petazzoni@...tlin.com>
Subject: Re: [PATCH wpan-next v5 00/11] ieee802154: Associations between devices

Hi,

On Wed, Sep 27, 2023 at 2:12 PM Miquel Raynal <miquel.raynal@...tlin.com> wrote:
>
> Hello,
>
> Now that we can discover our peer coordinators or make ourselves
> dynamically discoverable, we may use the information about surrounding
> devices to create PANs dynamically. This involves of course:
> * Requesting an association to a coordinator, waiting for the response
> * Sending a disassociation notification to a coordinator
> * Receiving an association request when we are coordinator, answering
>   the request (for now all devices are accepted up to a limit, to be
>   refined)
> * Sending a disassociation notification to a child
> * Users may request the list of associated devices (the parent and the
>   children).
>
> Here are a few example of userspace calls that can be made:
> iwpan dev <dev> associate pan_id 2 coord $COORD
> iwpan dev <dev> list_associations
> iwpan dev <dev> disassociate ext_addr $COORD
>
> I used a small using hwsim to scan for a coordinator, associate with
> it, look at the associations on both sides, disassociate from it and
> check the associations again:
> ./assoc-demo
> *** Scan ***
> PAN 0x0002 (on wpan1)
>         coordinator 0x060f3b35169a498f
>         page 0
>         channel 13
>         preamble code 0
>         mean prf 0
>         superframe spec. 0xcf11
>         LQI ff
> *** End of scan ***
> Associating wpan1 with coord0 0x060f3b35169a498f...
> Dumping coord0 assoc:
> child : 0x0b6f / 0xba7633ae47ccfb21
> Dumping wpan1 assoc:
> parent: 0xffff / 0x060f3b35169a498f
> Disassociating from wpan1
> Dumping coord0 assoc:
> Dumping wpan1 assoc:
>
> I could also successfully interact with a smaller device running Zephir,
> using its command line interface to associate and then disassociate from
> the Linux coordinator.
>
> Thanks!
> Miquèl
>
> Changes in v5:
> * Fixed (again) the helper supposed to check whether a device requesting
>   association/disassociation is already (or not) in our PAN. We don't
>   nee to check short addresses there.
> * Changed the name of the helper a second time to make it more relevant
>   and understandable:
>   cfg802154_device_in_pan() -> cfg802154_pan_device_is_matching()
> * Fixed a kernel test robot report where we would use an int instead of
>   a __le16. Solved that by using cpu_to_le16 like in the other places
>   where we use definitions as arguments.
>
> Changes in v4:
> * Ensured any disassociation would only be processed if the destination
>   pan ID matches ours.
> * Association requests should be made using extended addressing, it's
>   the specification, so ensure this is true. Doing so helps reducing the
>   checks down the road.
> * Updated a copyright from 2021 to 2023.
> * Improved the comment for cfg802154_device_in_pan() and only accept
>   extended addressing when using this internal function because there is
>   no point in checking short addresses here.
> * Move nl802154_prepare_wpan_dev_dump() and
>   nl802154_finish_wpan_dev_dump() outside of a
>   CONFIG_IEEE802154_NL802154_EXPERIMENTAL #ifdef bloc as now used in
>   regular code (not only experimental).
> * Added a missing return value in the kernel doc of
>   cfg802154_device_is_associated().
>
> Changes in v3:
> * Clarify a helper which compares if two devices seem to be identical by
>   adding two comments. This is a static function that is only used by
>   the PAN management core to operate or not an
>   association/disassociation request. In this helper, a new check is
>   introduced to be sure we compare fields which have been populated.
> * Dropped the "association_generation" counter and all its uses along
>   the code. I tried to mimic some other counter but I agree it is not
>   super useful and could be dropped anyway.
> * Dropped a faulty sequence number hardcoded to 10. This had no impact
>   because a few lines later the same entry was set to a valid value.
>
> Changes in v2:
> * Drop the misleading IEEE802154_ADDR_LONG_BROADCAST definition and its
>   only use which was useless anyway.
> * Clarified how devices are defined when the user requests to associate
>   with a coordinator: for now only the extended address of the
>   coordinator is relevant so this is the only address we care about.
> * Drop a useless NULL check before a kfree() call.
> * Add a check when allocating a child short address: it must be
>   different than ours.
> * Rebased on top of v6.5.

Acked-by: Alexander Aring <aahringo@...hat.com>

Thanks for working on this!

- Alex

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