hostapd: Perform multi-BSS CSA for DFS properly

Currently hostapd data structures aren't ready for multi-channel BSSes,
so make DFS work now at least with single-channel multi-BSS channel
switching.

Signed-off-by: Michal Kazior <michal.kazior@tieto.com>

src/ap/dfs.c

@@ -774,7 +774,7 @@ static int hostapd_dfs_start_channel_switch(struct hostapd_iface *iface)
 	u8 vht_oper_centr_freq_seg1_idx;
 	int skip_radar = 1;
 	struct csa_settings csa_settings;
-	struct hostapd_data *hapd = iface->bss[0];
+	unsigned int i;
 	int err = 1;
 
 	wpa_printf(MSG_DEBUG, "%s called (CAC active: %s, CSA active: %s)",
@@ -853,7 +853,12 @@ static int hostapd_dfs_start_channel_switch(struct hostapd_iface *iface)
 		return err;
 	}
 
-	err = hostapd_switch_channel(hapd, &csa_settings);
+	for (i = 0; i < iface->num_bss; i++) {
+		err = hostapd_switch_channel(iface->bss[i], &csa_settings);
+		if (err)
+			break;
+	}
+
 	if (err) {
 		wpa_printf(MSG_WARNING, "DFS failed to schedule CSA (%d) - trying fallback",
 			   err);