From: Johannes Berg <johannes.berg@xxxxxxxxx>
Currently, mac80211 uses the power constraint IE, and reduces
the regulatory max TX power by it. This can cause issues if
the AP is advertising a large power constraint value matching
a high TX power in its country IE, for example in this case:
...
Country: US Environment: Indoor/Outdoor
...
Channels [157 - 157] @ 30 dBm
...
Power constraint: 13 dB
...
What happened here is that our local regulatory TX power is
15 dBm, and gets reduced by 13 dB so we end up with only
2 dBm effective TX power, which is way too low.
Instead, handle the country IE/power constraint IE combined
and restrict our TX power to the max of the regulatory power
and the maximum power advertised by the AP, in this case
17 dBm (= 30 dBm - 13 dB).
Signed-off-by: Johannes Berg <johannes.berg@xxxxxxxxx>
---
net/mac80211/ieee80211_i.h | 2 +-
net/mac80211/main.c | 8 +++---
net/mac80211/mlme.c | 58 ++++++++++++++++++++++++++++++++------------
3 files changed, 47 insertions(+), 21 deletions(-)
diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h
index 2eee293..8937056 100644
--- a/net/mac80211/ieee80211_i.h
+++ b/net/mac80211/ieee80211_i.h
@@ -1052,7 +1052,7 @@ struct ieee80211_local {
bool disable_dynamic_ps;
int user_power_level; /* in dBm */
- int power_constr_level; /* in dBm */
+ int ap_power_level; /* in dBm */
enum ieee80211_smps_mode smps_mode;
diff --git a/net/mac80211/main.c b/net/mac80211/main.c
index c26e231..412f1aa 100644
--- a/net/mac80211/main.c
+++ b/net/mac80211/main.c
@@ -150,13 +150,11 @@ int ieee80211_hw_config(struct ieee80211_local *local, u32 changed)
if (test_bit(SCAN_SW_SCANNING, &local->scanning) ||
test_bit(SCAN_ONCHANNEL_SCANNING, &local->scanning) ||
- test_bit(SCAN_HW_SCANNING, &local->scanning))
+ test_bit(SCAN_HW_SCANNING, &local->scanning) ||
+ !local->ap_power_level)
power = chan->max_power;
else
- power = local->power_constr_level ?
- min(chan->max_power,
- (chan->max_reg_power - local->power_constr_level)) :
- chan->max_power;
+ power = min(chan->max_power, local->ap_power_level);
if (local->user_power_level >= 0)
power = min(power, local->user_power_level);
diff --git a/net/mac80211/mlme.c b/net/mac80211/mlme.c
index 6f64364..92b035b 100644
--- a/net/mac80211/mlme.c
+++ b/net/mac80211/mlme.c
@@ -796,16 +796,45 @@ void ieee80211_sta_process_chanswitch(struct ieee80211_sub_if_data *sdata,
}
static void ieee80211_handle_pwr_constr(struct ieee80211_sub_if_data *sdata,
- u16 capab_info, u8 *pwr_constr_elem)
+ struct ieee80211_channel *channel,
+ const u8 *country_ie, u8 country_ie_len,
+ const u8 *pwr_constr_elem)
{
- struct ieee80211_conf *conf = &sdata->local->hw.conf;
+ struct ieee80211_country_ie_triplet *triplet;
+ int chan = ieee80211_frequency_to_channel(channel->center_freq);
+ int chan_pwr;
+ bool have_chan_pwr = false;
- if (!(capab_info & WLAN_CAPABILITY_SPECTRUM_MGMT))
+ /* Invalid IE */
+ if (country_ie_len % 2 || country_ie_len < IEEE80211_COUNTRY_IE_MIN_LEN)
return;
- if ((*pwr_constr_elem <= conf->channel->max_reg_power) &&
- (*pwr_constr_elem != sdata->local->power_constr_level)) {
- sdata->local->power_constr_level = *pwr_constr_elem;
+ triplet = (void *)(country_ie + 3);
+ country_ie_len -= 3;
+
+ /* find channel */
+ while (country_ie_len >= 3) {
+ if (triplet->chans.first_channel >=
+ IEEE80211_COUNTRY_EXTENSION_ID)
+ goto next;
+
+ /* XXX: How to use triplet->chans.num_channels? */
+ if (triplet->chans.first_channel == chan) {
+ have_chan_pwr = true;
+ chan_pwr = triplet->chans.max_power;
+ break;
+ }
+
+ next:
+ triplet++;
+ country_ie_len -= 3;
+ }
+
+ if (!have_chan_pwr)
+ return;
+
+ if (*pwr_constr_elem <= chan_pwr) {
+ sdata->local->ap_power_level = chan_pwr - *pwr_constr_elem;
ieee80211_hw_config(sdata->local, 0);
}
}
@@ -1396,7 +1425,7 @@ static void ieee80211_set_disassoc(struct ieee80211_sub_if_data *sdata,
memset(&ifmgd->ht_capa, 0, sizeof(ifmgd->ht_capa));
memset(&ifmgd->ht_capa_mask, 0, sizeof(ifmgd->ht_capa_mask));
- local->power_constr_level = 0;
+ local->ap_power_level = 0;
del_timer_sync(&local->dynamic_ps_timer);
cancel_work_sync(&local->dynamic_ps_enable_work);
@@ -2491,14 +2520,13 @@ static void ieee80211_rx_mgmt_beacon(struct ieee80211_sub_if_data *sdata,
bssid, true);
}
- /* Note: country IE parsing is done for us by cfg80211 */
- if (elems.country_elem) {
- /* TODO: IBSS also needs this */
- if (elems.pwr_constr_elem)
- ieee80211_handle_pwr_constr(sdata,
- le16_to_cpu(mgmt->u.probe_resp.capab_info),
- elems.pwr_constr_elem);
- }
+ if (elems.country_elem && elems.pwr_constr_elem &&
+ mgmt->u.probe_resp.capab_info &
+ cpu_to_le16(WLAN_CAPABILITY_SPECTRUM_MGMT))
+ ieee80211_handle_pwr_constr(sdata, local->oper_channel,
+ elems.country_elem,
+ elems.country_elem_len,
+ elems.pwr_constr_elem);
ieee80211_bss_info_change_notify(sdata, changed);
}
--
1.7.10.4
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