mac80211: IBSS fix scan request

In case of wide bandwidth (wider than 20MHz) used by IBSS,
scan all channels in chandef to be able to find neighboring
IBSS netwqworks that use the same overall channels but a different
control channel.

Signed-off-by: Janusz Dziedzic <[e-mail]>
Signed-off-by: Johannes Berg <[e-mail]>

net/mac80211/ibss.c

···
 
 	scan_width = cfg80211_chandef_to_scan_width(&ifibss->chandef);
 	ieee80211_request_ibss_scan(sdata, ifibss->ssid, ifibss->ssid_len,
-				    NULL, scan_width);
+				    NULL, 0, scan_width);
 }
 
 static void ieee80211_sta_create_ibss(struct ieee80211_sub_if_data *sdata)
···
 	__ieee80211_sta_join_ibss(sdata, bssid, sdata->vif.bss_conf.beacon_int,
 				  &ifibss->chandef, ifibss->basic_rates,
 				  capability, 0, true);
+}
+
+static unsigned ibss_setup_channels(struct wiphy *wiphy,
+				    struct ieee80211_channel **channels,
+				    unsigned int channels_max,
+				    u32 center_freq, u32 width)
+{
+	struct ieee80211_channel *chan = NULL;
+	unsigned int n_chan = 0;
+	u32 start_freq, end_freq, freq;
+
+	if (width <= 20) {
+		start_freq = center_freq;
+		end_freq = center_freq;
+	} else {
+		start_freq = center_freq - width / 2 + 10;
+		end_freq = center_freq + width / 2 - 10;
+	}
+
+	for (freq = start_freq; freq <= end_freq; freq += 20) {
+		chan = ieee80211_get_channel(wiphy, freq);
+		if (!chan)
+			continue;
+		if (n_chan >= channels_max)
+			return n_chan;
+
+		channels[n_chan] = chan;
+		n_chan++;
+	}
+
+	return n_chan;
+}
+
+static unsigned int
+ieee80211_ibss_setup_scan_channels(struct wiphy *wiphy,
+				   const struct cfg80211_chan_def *chandef,
+				   struct ieee80211_channel **channels,
+				   unsigned int channels_max)
+{
+	unsigned int n_chan = 0;
+	u32 width, cf1, cf2 = 0;
+
+	switch (chandef->width) {
+	case NL80211_CHAN_WIDTH_40:
+		width = 40;
+		break;
+	case NL80211_CHAN_WIDTH_80P80:
+		cf2 = chandef->center_freq2;
+		/* fall through */
+	case NL80211_CHAN_WIDTH_80:
+		width = 80;
+		break;
+	case NL80211_CHAN_WIDTH_160:
+		width = 160;
+		break;
+	default:
+		width = 20;
+		break;
+	}
+
+	cf1 = chandef->center_freq1;
+
+	n_chan = ibss_setup_channels(wiphy, channels, channels_max, cf1, width);
+
+	if (cf2)
+		n_chan += ibss_setup_channels(wiphy, &channels[n_chan],
+					      channels_max - n_chan, cf2,
+					      width);
+
+	return n_chan;
 }
 
 /*
···
 	/* Selected IBSS not found in current scan results - try to scan */
 	if (time_after(jiffies, ifibss->last_scan_completed +
 					IEEE80211_SCAN_INTERVAL)) {
+		struct ieee80211_channel *channels[8];
+		unsigned int num;
+
 		sdata_info(sdata, "Trigger new scan to find an IBSS to join\n");
 
+		num = ieee80211_ibss_setup_scan_channels(local->hw.wiphy,
+							 &ifibss->chandef,
+							 channels,
+							 ARRAY_SIZE(channels));
 		scan_width = cfg80211_chandef_to_scan_width(&ifibss->chandef);
 		ieee80211_request_ibss_scan(sdata, ifibss->ssid,
-					    ifibss->ssid_len, chan,
+					    ifibss->ssid_len, channels, num,
 					    scan_width);
 	} else {
 		int interval = IEEE80211_SCAN_INTERVAL;

net/mac80211/ieee80211_i.h

···
 void ieee80211_scan_work(struct work_struct *work);
 int ieee80211_request_ibss_scan(struct ieee80211_sub_if_data *sdata,
 				const u8 *ssid, u8 ssid_len,
-				struct ieee80211_channel *chan,
+				struct ieee80211_channel **channels,
+				unsigned int n_channels,
 				enum nl80211_bss_scan_width scan_width);
 int ieee80211_request_scan(struct ieee80211_sub_if_data *sdata,
 			   struct cfg80211_scan_request *req);

net/mac80211/scan.c

···
 
 int ieee80211_request_ibss_scan(struct ieee80211_sub_if_data *sdata,
 				const u8 *ssid, u8 ssid_len,
-				struct ieee80211_channel *chan,
+				struct ieee80211_channel **channels,
+				unsigned int n_channels,
 				enum nl80211_bss_scan_width scan_width)
 {
 	struct ieee80211_local *local = sdata->local;
-	int ret = -EBUSY;
+	int ret = -EBUSY, i, n_ch = 0;
 	enum ieee80211_band band;
 
 	mutex_lock(&local->mtx);
···
 		goto unlock;
 
 	/* fill internal scan request */
-	if (!chan) {
-		int i, max_n;
-		int n_ch = 0;
+	if (!channels) {
+		int max_n;
 
 		for (band = 0; band < IEEE80211_NUM_BANDS; band++) {
 			if (!local->hw.wiphy->bands[band])
···
 
 		local->int_scan_req->n_channels = n_ch;
 	} else {
-		if (WARN_ON_ONCE(chan->flags & (IEEE80211_CHAN_NO_IR |
-						IEEE80211_CHAN_DISABLED)))
+		for (i = 0; i < n_channels; i++) {
+			if (channels[i]->flags & (IEEE80211_CHAN_NO_IR |
+						  IEEE80211_CHAN_DISABLED))
+				continue;
+
+			local->int_scan_req->channels[n_ch] = channels[i];
+			n_ch++;
+		}
+
+		if (WARN_ON_ONCE(n_ch == 0))
 			goto unlock;
 
-		local->int_scan_req->channels[0] = chan;
-		local->int_scan_req->n_channels = 1;
+		local->int_scan_req->n_channels = n_ch;
 	}
 
 	local->int_scan_req->ssids = &local->scan_ssid;