From 55413ce072aaf52d583e36e5401a51857cb9ab1f Mon Sep 17 00:00:00 2001
From: Jouni Malinen <j@w1.fi>
Date: Sun, 28 Jun 2015 18:14:58 +0300
Subject: [PATCH] P2P: Do not allow 40 MHz co-ex PRI/SEC switch to force MCC

Do not allow 40 MHz co-ex PRI/SEC switch to force us to change our PRI
channel if we have an existing connection on the selected PRI channel
since doing multi-channel concurrency is likely to cause more harm than
using different PRI/SEC selection in environment with multiple BSSes on
these two channels with mixed 20 MHz or PRI channel selection.

Signed-off-by: Jouni Malinen <j@w1.fi>
---
 src/ap/ap_config.h   |  1 +
 src/ap/hw_features.c | 10 ++++++++--
 wpa_supplicant/ap.c  | 23 +++++++++++++++++++++++
 3 files changed, 32 insertions(+), 2 deletions(-)

diff --git a/src/ap/ap_config.h b/src/ap/ap_config.h
index c14eeda4b..2e7c1380b 100644
--- a/src/ap/ap_config.h
+++ b/src/ap/ap_config.h
@@ -619,6 +619,7 @@ struct hostapd_config {
 	u16 ht_capab;
 	int ieee80211n;
 	int secondary_channel;
+	int no_pri_sec_switch;
 	int require_ht;
 	int obss_interval;
 	u32 vht_capab;
diff --git a/src/ap/hw_features.c b/src/ap/hw_features.c
index 28324a8ee..7cb7e8804 100644
--- a/src/ap/hw_features.c
+++ b/src/ap/hw_features.c
@@ -260,8 +260,14 @@ static int ieee80211n_check_40mhz_5g(struct hostapd_iface *iface,
 
 	res = check_40mhz_5g(iface->current_mode, scan_res, pri_chan, sec_chan);
 
-	if (res == 2)
-		ieee80211n_switch_pri_sec(iface);
+	if (res == 2) {
+		if (iface->conf->no_pri_sec_switch) {
+			wpa_printf(MSG_DEBUG,
+				   "Cannot switch PRI/SEC channels due to local constraint");
+		} else {
+			ieee80211n_switch_pri_sec(iface);
+		}
+	}
 
 	return !!res;
 }
diff --git a/wpa_supplicant/ap.c b/wpa_supplicant/ap.c
index f3960c5eb..aaea52428 100644
--- a/wpa_supplicant/ap.c
+++ b/wpa_supplicant/ap.c
@@ -142,6 +142,29 @@ void wpa_supplicant_conf_ap_ht(struct wpa_supplicant *wpa_s,
 			}
 		}
 	}
+
+	if (conf->secondary_channel) {
+		struct wpa_supplicant *iface;
+
+		for (iface = wpa_s->global->ifaces; iface; iface = iface->next)
+		{
+			if (iface == wpa_s ||
+			    iface->wpa_state < WPA_AUTHENTICATING ||
+			    (int) iface->assoc_freq != ssid->frequency)
+				continue;
+
+			/*
+			 * Do not allow 40 MHz co-ex PRI/SEC switch to force us
+			 * to change our PRI channel since we have an existing,
+			 * concurrent connection on that channel and doing
+			 * multi-channel concurrency is likely to cause more
+			 * harm than using different PRI/SEC selection in
+			 * environment with multiple BSSes on these two channels
+			 * with mixed 20 MHz or PRI channel selection.
+			 */
+			conf->no_pri_sec_switch = 1;
+		}
+	}
 #endif /* CONFIG_IEEE80211N */
 }