From 9e737f08d41ab089b0737d3c002a62c4175be241 Mon Sep 17 00:00:00 2001
From: Pontus Fuchs <pontus.fuchs@gmail.com>
Date: Sun, 3 Feb 2013 18:14:05 +0200
Subject: [PATCH] Update scan interval gracefully

When the scan interval is changed the new interval is effective
after the old interval timer fires off one last time. This can cause
an unacceptable long delay when updating the interval.

Change this behaviour to use MIN(left of old interval, new interval)
for the scan interval following the interval change.

Signed-hostap: Pontus Fuchs <pontus.fuchs@gmail.com>
---
 wpa_supplicant/scan.c           | 21 +++++++++++++++++++++
 wpa_supplicant/scan.h           |  1 +
 wpa_supplicant/wpa_supplicant.c |  2 +-
 3 files changed, 23 insertions(+), 1 deletion(-)

diff --git a/wpa_supplicant/scan.c b/wpa_supplicant/scan.c
index d2b671a9a..25a9ef821 100644
--- a/wpa_supplicant/scan.c
+++ b/wpa_supplicant/scan.c
@@ -816,6 +816,27 @@ scan:
 }
 
 
+void wpa_supplicant_update_scan_int(struct wpa_supplicant *wpa_s, int sec)
+{
+	struct os_time remaining, new_int;
+	int cancelled;
+
+	cancelled = eloop_cancel_timeout_one(wpa_supplicant_scan, wpa_s, NULL,
+					     &remaining);
+
+	new_int.sec = sec;
+	new_int.usec = 0;
+	if (cancelled && os_time_before(&remaining, &new_int)) {
+		new_int.sec = remaining.sec;
+		new_int.usec = remaining.usec;
+	}
+
+	eloop_register_timeout(new_int.sec, new_int.usec, wpa_supplicant_scan,
+			       wpa_s, NULL);
+	wpa_s->scan_interval = sec;
+}
+
+
 /**
  * wpa_supplicant_req_scan - Schedule a scan for neighboring access points
  * @wpa_s: Pointer to wpa_supplicant data
diff --git a/wpa_supplicant/scan.h b/wpa_supplicant/scan.h
index 5096287af..7a9b232d0 100644
--- a/wpa_supplicant/scan.h
+++ b/wpa_supplicant/scan.h
@@ -32,5 +32,6 @@ struct wpabuf * wpa_scan_get_vendor_ie_multi(const struct wpa_scan_res *res,
 					     u32 vendor_type);
 int wpa_supplicant_filter_bssid_match(struct wpa_supplicant *wpa_s,
 				      const u8 *bssid);
+void wpa_supplicant_update_scan_int(struct wpa_supplicant *wpa_s, int sec);
 
 #endif /* SCAN_H */
diff --git a/wpa_supplicant/wpa_supplicant.c b/wpa_supplicant/wpa_supplicant.c
index 64f5c1bde..21bd73a73 100644
--- a/wpa_supplicant/wpa_supplicant.c
+++ b/wpa_supplicant/wpa_supplicant.c
@@ -1980,7 +1980,7 @@ int wpa_supplicant_set_scan_interval(struct wpa_supplicant *wpa_s,
 	}
 	wpa_msg(wpa_s, MSG_DEBUG, "Setting scan interval: %d sec",
 		scan_interval);
-	wpa_s->scan_interval = scan_interval;
+	wpa_supplicant_update_scan_int(wpa_s, scan_interval);
 
 	return 0;
 }