On Tue, 2009-03-31 at 21:28 -0400, Luis R. Rodriguez wrote:
> + * @NL80211_CMD_REG_BEACON_HINT: indicates to userspace that an AP beacon
> + * has been found while world roaming thus enabling active scan or
> + * any mode of operation that initiates TX (beacons) on a channel
> + * where we would not have been able to do either before. As an example
> + * if you are world roaming (regulatory domain set to world or if your
> + * driver is using a custom world roaming regulatory domain) and while
> + * doing a passive scan on the 5 GHz band you find an AP there (if not
> + * on a DFS channel) you will now be able to actively scan for that AP
> + * or use AP mode on your card on that same channel. Note that this will
> + * never be used for channels 1-11 on the 2 GHz band as they are always
> + * enabled world wide. This beacon hint is only sent if your device had
> + * either disabled active scanning or beaconing on a channel. We send to
> + * userspace the wiphy on which we removed a restriction from
> + * (%NL80211_ATTR_WIPHY) and the channel on which this occurred
> + * before (%NL80211_ATTR_FREQ_BEFORE) and after (%NL80211_ATTR_FREQ_AFTER)
> + * the beacon hint was processed.
I wonder -- are there other reasons we may ever update the regdomain? I
could imagine the CMD being REG_UPDATE with an ATTR_REASON or so? Or
just using REG_CHANGE with NL80211_REGDOM_TYPE_WORLD _and_ the new
channel change attributes?
> +static int nl80211_put_beacon_hint_channel(void *hdr,
> + struct sk_buff *msg,
> + enum nl80211_attrs attribute,
> + struct ieee80211_channel *chan)
> +{
> + struct nlattr *nl_freq;
> +
> + nl_freq = nla_nest_start(msg, attribute);
> + if (!nl_freq)
> + goto nla_put_failure;
> +
> + NLA_PUT_U32(msg, NL80211_FREQUENCY_ATTR_FREQ,
> + chan->center_freq);
> +
> + if (chan->flags & IEEE80211_CHAN_PASSIVE_SCAN)
> + NLA_PUT_FLAG(msg, NL80211_FREQUENCY_ATTR_PASSIVE_SCAN);
> + if (chan->flags & IEEE80211_CHAN_NO_IBSS)
> + NLA_PUT_FLAG(msg, NL80211_FREQUENCY_ATTR_NO_IBSS);
> +
> + nla_nest_end(msg, nl_freq);
> +
> + return 0;
I think you should send all possible channel attributes here -- please
refactor the code and extract the bit that sends a channel from
nl80211_send_wiphy(), this bit:
NLA_PUT_U32(msg, NL80211_FREQUENCY_ATTR_FREQ,...)
..
NLA_PUT_U32(msg, NL80211_FREQUENCY_ATTR_MAX_TX_POWER,...)
put it into a new function that takes a msg and channel pointer and call
it twice.
Does the relaxing we do on receiving beacons only apply to a single
wiphy though?
> + /*
> + * Since we are applying the beacon hint to a wiphy we know its
> + * wiphy_idx is valid
> + */
> + NLA_PUT_U32(msg, NL80211_ATTR_WIPHY, get_wiphy_idx(wiphy));
You're sending out the wiphy here.
And I just realised there's a bug in the existing code:
> @@ -1070,18 +1062,26 @@ static void handle_reg_beacon(struct wiphy *wiphy,
> if (likely(chan->center_freq != reg_beacon->chan.center_freq))
> return;
>
> + if (chan->beacon_found)
> + return;
> +
> + chan->beacon_found = true;
> +
> + chan_before.center_freq = chan->center_freq;
> + chan_before.flags = chan->flags;
> +
> if (chan->flags & IEEE80211_CHAN_PASSIVE_SCAN) {
> chan->flags &= ~IEEE80211_CHAN_PASSIVE_SCAN;
> - REG_DEBUG_BEACON_FLAG("active scanning");
> + channel_changed = true;
> }
>
> if (chan->flags & IEEE80211_CHAN_NO_IBSS) {
> chan->flags &= ~IEEE80211_CHAN_NO_IBSS;
> - REG_DEBUG_BEACON_FLAG("beaconing");
> + channel_changed = true;
> }
This is incorrect, it has to be like this:
if ((chan->flags & FLAG) && !(chan->orig_flags & FLAG)) {
chan->flags &= ~FLAG;
channel_changed = true;
}
to take into account the flags the _driver_ had already set on the
channel. This is important for Intel hardware -- if you lift the IBSS
restriction on a channel that iwlwifi thinks should not use IBSS then
the firmware will hate you if you try to use it anyway. Now, I think
iwlwifi isn't world-roaming in that sense, but it should still be fixed!
Does this mean though you're sending one event per wiphy? Just
wondering, it's probably acceptable.
johannes
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