Hi,
On Tue, May 17, 2022 at 12:35 PM Miquel Raynal
<miquel.raynal@xxxxxxxxxxx> wrote:
>
> In order to be able to detect possible conflicts between the net
> interface core and the ieee802154 core, let's add a warning in the slow
> path: we want to be sure that whenever we start an asynchronous MLME
> transmission (which can be fully asynchronous) the net core somehow
> agrees that this transmission is possible, ie. the device was not
> stopped. Warning in this case would allow us to track down more easily
> possible issues with the MLME logic if we ever get reports.
>
> Unlike in the hot path, such a situation cannot be handled.
>
> Signed-off-by: Miquel Raynal <miquel.raynal@xxxxxxxxxxx>
> ---
> net/mac802154/tx.c | 25 +++++++++++++++++++++++++
> 1 file changed, 25 insertions(+)
>
> diff --git a/net/mac802154/tx.c b/net/mac802154/tx.c
> index e36aca788ea2..53a8be822e33 100644
> --- a/net/mac802154/tx.c
> +++ b/net/mac802154/tx.c
> @@ -132,6 +132,25 @@ int ieee802154_sync_and_hold_queue(struct ieee802154_local *local)
> return ret;
> }
>
> +static bool ieee802154_netif_is_down(struct ieee802154_local *local)
> +{
> + struct ieee802154_sub_if_data *sdata;
> + bool is_down = true;
> +
> + rcu_read_lock();
> + list_for_each_entry_rcu(sdata, &local->interfaces, list) {
> + if (!sdata->dev)
> + continue;
> +
> + is_down = !(sdata->dev->flags & IFF_UP);
> + if (is_down)
> + break;
I thought that the helper would be "netif_running()". It seems there
are multiple ways to check if an interface is up.
> + }
> + rcu_read_unlock();
> +
> + return is_down;
> +}
> +
> static int ieee802154_mlme_op_pre(struct ieee802154_local *local)
> {
> return ieee802154_sync_and_hold_queue(local);
> @@ -150,6 +169,12 @@ static int ieee802154_mlme_tx(struct ieee802154_local *local, struct sk_buff *sk
> if (!local->open_count)
> return -EBUSY;
>
> + /* Warn if the ieee802154 core thinks MLME frames can be sent while the
> + * net interface expects this cannot happen.
> + */
> + if (WARN_ON_ONCE(ieee802154_netif_is_down(local)))
> + return -EHOSTDOWN;
maybe also ENETDOWN? Also there is a missing rtnl_unlock().
- Alex
