netdev - Re: [PATCH wpan-next 07/11] mac802154: Handle association requests from peers

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Message-ID: <CAK-6q+hWsLSy8vx_Hiwo0gRDYsW4Y7U=sQbAi5Na7BXQoOHWhw@mail.gmail.com>
Date: Sat, 3 Jun 2023 07:28:25 -0400
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 07/11] mac802154: Handle association requests
 from peers

Hi,

On Thu, Jun 1, 2023 at 11:50 AM Miquel Raynal <miquel.raynal@...tlin.com> wrote:
>
> Coordinators may have to handle association requests from peers which
> want to join the PAN. The logic involves:
> - Acknowledging the request (done by hardware)
> - If requested, a random short address that is free on this PAN should
>   be chosen for the device.
> - Sending an association response with the short address allocated for
>   the peer and expecting it to be ack'ed.
>
> If anything fails during this procedure, the peer is considered not
> associated.
>
> Signed-off-by: Miquel Raynal <miquel.raynal@...tlin.com>
> ---
>  include/net/cfg802154.h         |   7 ++
>  include/net/ieee802154_netdev.h |   6 ++
>  net/ieee802154/core.c           |   7 ++
>  net/ieee802154/pan.c            |  27 ++++++
>  net/mac802154/ieee802154_i.h    |   2 +
>  net/mac802154/rx.c              |   8 ++
>  net/mac802154/scan.c            | 147 ++++++++++++++++++++++++++++++++
>  7 files changed, 204 insertions(+)
>
> diff --git a/include/net/cfg802154.h b/include/net/cfg802154.h
> index 01bc6c2da7b9..4404072365e7 100644
> --- a/include/net/cfg802154.h
> +++ b/include/net/cfg802154.h
> @@ -582,4 +582,11 @@ struct ieee802154_pan_device *
>  cfg802154_device_is_child(struct wpan_dev *wpan_dev,
>                           struct ieee802154_addr *target);
>
> +/**
> + * cfg802154_get_free_short_addr - Get a free address among the known devices
> + * @wpan_dev: the wpan device
> + * @return: a random short address expectedly unused on our PAN
> + */
> +__le16 cfg802154_get_free_short_addr(struct wpan_dev *wpan_dev);
> +
>  #endif /* __NET_CFG802154_H */
> diff --git a/include/net/ieee802154_netdev.h b/include/net/ieee802154_netdev.h
> index 16194356cfe7..4de858f9929e 100644
> --- a/include/net/ieee802154_netdev.h
> +++ b/include/net/ieee802154_netdev.h
> @@ -211,6 +211,12 @@ struct ieee802154_association_req_frame {
>         struct ieee802154_assoc_req_pl assoc_req_pl;
>  };
>
> +struct ieee802154_association_resp_frame {
> +       struct ieee802154_hdr mhr;
> +       struct ieee802154_mac_cmd_pl mac_pl;
> +       struct ieee802154_assoc_resp_pl assoc_resp_pl;
> +};
> +
>  struct ieee802154_disassociation_notif_frame {
>         struct ieee802154_hdr mhr;
>         struct ieee802154_mac_cmd_pl mac_pl;
> diff --git a/net/ieee802154/core.c b/net/ieee802154/core.c
> index 8bf01bb7e858..39674db64336 100644
> --- a/net/ieee802154/core.c
> +++ b/net/ieee802154/core.c
> @@ -200,11 +200,18 @@ EXPORT_SYMBOL(wpan_phy_free);
>
>  static void cfg802154_free_peer_structures(struct wpan_dev *wpan_dev)
>  {
> +       struct ieee802154_pan_device *child, *tmp;
> +
>         mutex_lock(&wpan_dev->association_lock);
>
>         if (wpan_dev->parent)
>                 kfree(wpan_dev->parent);
>
> +       list_for_each_entry_safe(child, tmp, &wpan_dev->children, node) {
> +               list_del(&child->node);
> +               kfree(child);
> +       }
> +
>         wpan_dev->association_generation++;
>
>         mutex_unlock(&wpan_dev->association_lock);
> diff --git a/net/ieee802154/pan.c b/net/ieee802154/pan.c
> index 477e8dad0cf0..7756906c201d 100644
> --- a/net/ieee802154/pan.c
> +++ b/net/ieee802154/pan.c
> @@ -66,3 +66,30 @@ cfg802154_device_is_child(struct wpan_dev *wpan_dev,
>         return NULL;
>  }
>  EXPORT_SYMBOL_GPL(cfg802154_device_is_child);
> +
> +__le16 cfg802154_get_free_short_addr(struct wpan_dev *wpan_dev)
> +{
> +       struct ieee802154_pan_device *child;
> +       __le16 addr;
> +
> +       lockdep_assert_held(&wpan_dev->association_lock);
> +
> +       do {
> +               get_random_bytes(&addr, 2);

This is combined with the max associations setting? I am not sure if
this is the best way to get free values from a u16 value where we have
some data structure of "given" addresses to a node. I recently was
looking into idr/xarray data structure... maybe we can use something
from there.

- Alex