From e2f5a9889a3a2bb8f1eed0cf274c7fbbabe3e9de Mon Sep 17 00:00:00 2001
From: Dmitry Shmidt <dimitrysh@google.com>
Date: Mon, 11 Nov 2013 11:13:17 -0800
Subject: [PATCH] Deplete scan request if new time is less than remaining

This avoids pushing out previous scheduled scan requests based on new
events.

Signed-off-by: Dmitry Shmidt <dimitrysh@google.com>
---
 src/utils/eloop.c     | 31 +++++++++++++++++++++++++++++++
 src/utils/eloop.h     | 16 ++++++++++++++++
 src/utils/eloop_win.c | 31 +++++++++++++++++++++++++++++++
 wpa_supplicant/scan.c |  7 +++++++
 4 files changed, 85 insertions(+)

diff --git a/src/utils/eloop.c b/src/utils/eloop.c
index ddddcf17c..2d6aac7e0 100644
--- a/src/utils/eloop.c
+++ b/src/utils/eloop.c
@@ -599,6 +599,37 @@ int eloop_is_timeout_registered(eloop_timeout_handler handler,
 }
 
 
+int eloop_deplete_timeout(unsigned int req_secs, unsigned int req_usecs,
+			  eloop_timeout_handler handler, void *eloop_data,
+			  void *user_data)
+{
+	struct os_time now, requested, remaining;
+	struct eloop_timeout *tmp;
+
+	dl_list_for_each(tmp, &eloop.timeout, struct eloop_timeout, list) {
+		if (tmp->handler == handler &&
+		    tmp->eloop_data == eloop_data &&
+		    tmp->user_data == user_data) {
+			requested.sec = req_secs;
+			requested.usec = req_usecs;
+			os_get_time(&now);
+			os_time_sub(&tmp->time, &now, &remaining);
+			if (os_time_before(&requested, &remaining)) {
+				eloop_cancel_timeout(handler, eloop_data,
+						     user_data);
+				eloop_register_timeout(requested.sec,
+						       requested.usec,
+						       handler, eloop_data,
+						       user_data);
+				return 1;
+			}
+		}
+	}
+
+	return 0;
+}
+
+
 int eloop_replenish_timeout(unsigned int req_secs, unsigned int req_usecs,
 			    eloop_timeout_handler handler, void *eloop_data,
 			    void *user_data)
diff --git a/src/utils/eloop.h b/src/utils/eloop.h
index befb0703e..274714f88 100644
--- a/src/utils/eloop.h
+++ b/src/utils/eloop.h
@@ -222,6 +222,22 @@ int eloop_cancel_timeout_one(eloop_timeout_handler handler,
 int eloop_is_timeout_registered(eloop_timeout_handler handler,
 				void *eloop_data, void *user_data);
 
+/**
+ * eloop_deplete_timeout - Deplete a timeout that is already registered
+ * @req_secs: Requested number of seconds to the timeout
+ * @req_usecs: Requested number of microseconds to the timeout
+ * @handler: Matching callback function
+ * @eloop_data: Matching eloop_data
+ * @user_data: Matching user_data
+ * Returns: 1 if the timeout is depleted, 0 if no change is made
+ *
+ * Find a registered matching <handler,eloop_data,user_data> timeout. If found,
+ * deplete the timeout if remaining time is more than the requested time.
+ */
+int eloop_deplete_timeout(unsigned int req_secs, unsigned int req_usecs,
+			  eloop_timeout_handler handler, void *eloop_data,
+			  void *user_data);
+
 /**
  * eloop_replenish_timeout - Replenish a timeout that is already registered
  * @req_secs: Requested number of seconds to the timeout
diff --git a/src/utils/eloop_win.c b/src/utils/eloop_win.c
index 1f40530cf..e87d82ac9 100644
--- a/src/utils/eloop_win.c
+++ b/src/utils/eloop_win.c
@@ -354,6 +354,37 @@ int eloop_is_timeout_registered(eloop_timeout_handler handler,
 }
 
 
+int eloop_deplete_timeout(unsigned int req_secs, unsigned int req_usecs,
+			  eloop_timeout_handler handler, void *eloop_data,
+			  void *user_data)
+{
+	struct os_time now, requested, remaining;
+	struct eloop_timeout *tmp;
+
+	dl_list_for_each(tmp, &eloop.timeout, struct eloop_timeout, list) {
+		if (tmp->handler == handler &&
+		    tmp->eloop_data == eloop_data &&
+		    tmp->user_data == user_data) {
+			requested.sec = req_secs;
+			requested.usec = req_usecs;
+			os_get_time(&now);
+			os_time_sub(&tmp->time, &now, &remaining);
+			if (os_time_before(&requested, &remaining)) {
+				eloop_cancel_timeout(handler, eloop_data,
+						     user_data);
+				eloop_register_timeout(requested.sec,
+						       requested.usec,
+						       handler, eloop_data,
+						       user_data);
+				return 1;
+			}
+		}
+	}
+
+	return 0;
+}
+
+
 int eloop_replenish_timeout(unsigned int req_secs, unsigned int req_usecs,
 			    eloop_timeout_handler handler, void *eloop_data,
 			    void *user_data)
diff --git a/wpa_supplicant/scan.c b/wpa_supplicant/scan.c
index cfac768fb..47827f442 100644
--- a/wpa_supplicant/scan.c
+++ b/wpa_supplicant/scan.c
@@ -907,6 +907,13 @@ void wpa_supplicant_update_scan_int(struct wpa_supplicant *wpa_s, int sec)
  */
 void wpa_supplicant_req_scan(struct wpa_supplicant *wpa_s, int sec, int usec)
 {
+	if (eloop_deplete_timeout(sec, usec, wpa_supplicant_scan, wpa_s, NULL))
+	{
+		wpa_dbg(wpa_s, MSG_DEBUG, "Rescheduling scan request: %d sec %d usec",
+			sec, usec);
+		return;
+	}
+
 	/* If there's at least one network that should be specifically scanned
 	 * then don't cancel the scan and reschedule.  Some drivers do
 	 * background scanning which generates frequent scan results, and that