diff --git a/hostapd/config_file.c b/hostapd/config_file.c
index e3cad7c..9edbe63 100644
--- a/hostapd/config_file.c
+++ b/hostapd/config_file.c
@@ -1856,6 +1856,48 @@
 #endif /* CONFIG_WPS_NFC */
 
 
+#ifdef CONFIG_ACS
+static int hostapd_config_parse_acs_chan_bias(struct hostapd_config *conf,
+					      char *pos)
+{
+	struct acs_bias *bias = NULL, *tmp;
+	unsigned int num = 0;
+	char *end;
+
+	while (*pos) {
+		tmp = os_realloc_array(bias, num + 1, sizeof(*bias));
+		if (!tmp)
+			goto fail;
+		bias = tmp;
+
+		bias[num].channel = atoi(pos);
+		if (bias[num].channel <= 0)
+			goto fail;
+		pos = os_strchr(pos, ':');
+		if (!pos)
+			goto fail;
+		pos++;
+		bias[num].bias = strtod(pos, &end);
+		if (end == pos || bias[num].bias < 0.0)
+			goto fail;
+		pos = end;
+		if (*pos != ' ' && *pos != '\0')
+			goto fail;
+		num++;
+	}
+
+	os_free(conf->acs_chan_bias);
+	conf->acs_chan_bias = bias;
+	conf->num_acs_chan_bias = num;
+
+	return 0;
+fail:
+	os_free(bias);
+	return -1;
+}
+#endif /* CONFIG_ACS */
+
+
 static int hostapd_config_fill(struct hostapd_config *conf,
 			       struct hostapd_bss_config *bss,
 			       char *buf, char *pos, int line)
@@ -2283,12 +2325,11 @@
 		os_free(bss->ssid.wpa_passphrase);
 		bss->ssid.wpa_passphrase = os_strdup(pos);
 		if (bss->ssid.wpa_passphrase) {
-			os_free(bss->ssid.wpa_psk);
-			bss->ssid.wpa_psk = NULL;
+			hostapd_config_clear_wpa_psk(&bss->ssid.wpa_psk);
 			bss->ssid.wpa_passphrase_set = 1;
 		}
 	} else if (os_strcmp(buf, "wpa_psk") == 0) {
-		os_free(bss->ssid.wpa_psk);
+		hostapd_config_clear_wpa_psk(&bss->ssid.wpa_psk);
 		bss->ssid.wpa_psk = os_zalloc(sizeof(struct hostapd_wpa_psk));
 		if (bss->ssid.wpa_psk == NULL)
 			return 1;
@@ -2296,8 +2337,7 @@
 		    pos[PMK_LEN * 2] != '\0') {
 			wpa_printf(MSG_ERROR, "Line %d: Invalid PSK '%s'.",
 				   line, pos);
-			os_free(bss->ssid.wpa_psk);
-			bss->ssid.wpa_psk = NULL;
+			hostapd_config_clear_wpa_psk(&bss->ssid.wpa_psk);
 			return 1;
 		}
 		bss->ssid.wpa_psk->group = 1;
@@ -2508,6 +2548,12 @@
 			return 1;
 		}
 		conf->acs_num_scans = val;
+	} else if (os_strcmp(buf, "acs_chan_bias") == 0) {
+		if (hostapd_config_parse_acs_chan_bias(conf, pos)) {
+			wpa_printf(MSG_ERROR, "Line %d: invalid acs_chan_bias",
+				   line);
+			return -1;
+		}
 #endif /* CONFIG_ACS */
 	} else if (os_strcmp(buf, "dtim_period") == 0) {
 		bss->dtim_period = atoi(pos);
diff --git a/hostapd/ctrl_iface.c b/hostapd/ctrl_iface.c
index 54b17dc..86f1aa6 100644
--- a/hostapd/ctrl_iface.c
+++ b/hostapd/ctrl_iface.c
@@ -40,6 +40,7 @@
 #include "ap/hs20.h"
 #include "ap/wnm_ap.h"
 #include "ap/wpa_auth.h"
+#include "ap/beacon.h"
 #include "wps/wps_defs.h"
 #include "wps/wps.h"
 #include "config_file.h"
@@ -1955,6 +1956,9 @@
 	} else if (os_strncmp(buf, "DISASSOCIATE ", 13) == 0) {
 		if (hostapd_ctrl_iface_disassociate(hapd, buf + 13))
 			reply_len = -1;
+	} else if (os_strcmp(buf, "STOP_AP") == 0) {
+		if (hostapd_ctrl_iface_stop_ap(hapd))
+			reply_len = -1;
 #ifdef CONFIG_IEEE80211W
 #ifdef NEED_AP_MLME
 	} else if (os_strncmp(buf, "SA_QUERY ", 9) == 0) {
@@ -2047,6 +2051,9 @@
 	} else if (os_strncmp(buf, "DISABLE", 7) == 0) {
 		if (hostapd_ctrl_iface_disable(hapd->iface))
 			reply_len = -1;
+	} else if (os_strcmp(buf, "UPDATE_BEACON") == 0) {
+		if (ieee802_11_set_beacon(hapd))
+			reply_len = -1;
 #ifdef CONFIG_TESTING_OPTIONS
 	} else if (os_strncmp(buf, "RADAR ", 6) == 0) {
 		if (hostapd_ctrl_iface_radar(hapd, buf + 6))
diff --git a/hostapd/hostapd.conf b/hostapd/hostapd.conf
index 1e56959..dd05c2f 100644
--- a/hostapd/hostapd.conf
+++ b/hostapd/hostapd.conf
@@ -154,8 +154,19 @@
 # interference that may help choosing a better channel. This can also help fine
 # tune the ACS scan time in case a driver has different scan dwell times.
 #
+# acs_chan_bias is a space-separated list of <channel>:<bias> pairs. It can be
+# used to increase (or decrease) the likelihood of a specific channel to be
+# selected by the ACS algorithm. The total interference factor for each channel
+# gets multiplied by the specified bias value before finding the channel with
+# the lowest value. In other words, values between 0.0 and 1.0 can be used to
+# make a channel more likely to be picked while values larger than 1.0 make the
+# specified channel less likely to be picked. This can be used, e.g., to prefer
+# the commonly used 2.4 GHz band channels 1, 6, and 11 (which is the default
+# behavior on 2.4 GHz band if no acs_chan_bias parameter is specified).
+#
 # Defaults:
 #acs_num_scans=5
+#acs_chan_bias=1:0.8 6:0.8 11:0.8
 
 # Channel list restriction. This option allows hostapd to select one of the
 # provided channels when a channel should be automatically selected.