From 1fc41b776f712f321c1f355d391c6a5eaf79ebfa Mon Sep 17 00:00:00 2001
From: Jonathan McCrohan <jmccrohan@gmail.com>
Date: Sun, 18 Feb 2018 21:31:59 +0000
Subject: New upstream version 0.8.2

---
 iw_scan.c | 56 ++++++++++++++++++++++----------------------------------
 1 file changed, 22 insertions(+), 34 deletions(-)

(limited to 'iw_scan.c')

diff --git a/iw_scan.c b/iw_scan.c
index 6426f68..2748376 100644
--- a/iw_scan.c
+++ b/iw_scan.c
@@ -105,7 +105,7 @@ static int wait_event(struct nl_msg *msg, void *arg)
  * Returns true if scan results are available, false if scan was aborted.
  * Taken from iw:event.c:__do_listen_events
  */
-static bool wait_for_scan_events(struct scan_result *sr)
+static bool wait_for_scan_events(void)
 {
 	static const uint32_t cmds[] = {
 		NL80211_CMD_NEW_SCAN_RESULTS,
@@ -293,7 +293,8 @@ void sort_scan_list(struct scan_entry **headp)
 	*headp = head;
 }
 
-static void free_scan_list(struct scan_entry *head)
+/** De-allocate list. Use after all threads are terminated. */
+void free_scan_list(struct scan_entry *head)
 {
 	if (head) {
 		free_scan_list(head->next);
@@ -301,9 +302,9 @@ static void free_scan_list(struct scan_entry *head)
 	}
 }
 
-static void clear_scan_list(struct scan_result *sr)
+/** Initialize scan results. Requires lock to be taken. */
+void init_scan_list(struct scan_result *sr)
 {
-	pthread_mutex_lock(&sr->mutex);
 	free_scan_list(sr->head);
 	free(sr->channel_stats);
 	sr->head          = NULL;
@@ -311,7 +312,7 @@ static void clear_scan_list(struct scan_result *sr)
 	sr->msg[0]        = '\0';
 	sr->max_essid_len = MAX_ESSID_LEN;
 	memset(&(sr->num), 0, sizeof(sr->num));
-	pthread_mutex_unlock(&sr->mutex);
+	sr->mutex = (pthread_mutex_t)PTHREAD_MUTEX_INITIALIZER;
 }
 
 /*
@@ -366,28 +367,6 @@ static void compute_channel_stats(struct scan_result *sr)
 	sr->num.ch_stats = n < MAX_CH_STATS ? n : MAX_CH_STATS;
 }
 
-/*
- *	Scan results.
- */
-void scan_result_init(struct scan_result *sr)
-{
-	pthread_mutexattr_t ma;
-
-	memset(sr, 0, sizeof(*sr));
-	pthread_mutexattr_init(&ma);
-	if (pthread_mutexattr_setrobust(&ma, PTHREAD_MUTEX_ROBUST) < 0)
-		err_sys("Failed to set the mutex robust attribute");
-	pthread_mutex_init(&sr->mutex, &ma);
-}
-
-void scan_result_fini(struct scan_result *sr)
-{
-	/* FIXME: this may have a bug on resource de-allocation, if the main thread still holds the lock */
-	free_scan_list(sr->head);
-	free(sr->channel_stats);
-	pthread_mutex_destroy(&sr->mutex);
-}
-
 /** The actual scan thread. */
 void *do_scan(void *sr_ptr)
 {
@@ -402,15 +381,21 @@ void *do_scan(void *sr_ptr)
 
 	pthread_detach(pthread_self());
 	do {
-		clear_scan_list(sr);
-
 		ret = iw_nl80211_scan_trigger();
+
+		pthread_mutex_lock(&sr->mutex);
+		init_scan_list(sr);
 		switch(-ret) {
 		case 0:
 		case EBUSY:
 			/* Trigger returns -EBUSY if a scan request is pending or ready. */
-			if (!wait_for_scan_events(sr)) {
+			pthread_mutex_unlock(&sr->mutex);
+
+			/* Do not hold the lock while awaiting results. */
+			if (!wait_for_scan_events()) {
+				pthread_mutex_lock(&sr->mutex);
 				snprintf(sr->msg, sizeof(sr->msg), "Waiting for scan data...");
+				pthread_mutex_unlock(&sr->mutex);
 			} else {
 				pthread_mutex_lock(&sr->mutex);
 				ret = iw_nl80211_get_scan_data(sr);
@@ -426,8 +411,8 @@ void *do_scan(void *sr_ptr)
 			break;
 		case EPERM:
 			if (!has_net_admin_capability())
-				snprintf(sr->msg, sizeof(sr->msg),
-					 "This screen requires CAP_NET_ADMIN permissions");
+				snprintf(sr->msg, sizeof(sr->msg), "This screen requires CAP_NET_ADMIN permissions");
+			pthread_mutex_unlock(&sr->mutex);
 			return NULL;
 		case EFAULT:
 			/* EFAULT can occur after a window resizing event: temporary, fall through. */
@@ -435,18 +420,21 @@ void *do_scan(void *sr_ptr)
 		case EAGAIN:
 			/* Temporary errors. */
 			snprintf(sr->msg, sizeof(sr->msg), "Waiting for device to become ready ...");
+			pthread_mutex_unlock(&sr->mutex);
 			break;
 		case ENETDOWN:
 			if (!if_is_up(conf_ifname())) {
 				snprintf(sr->msg, sizeof(sr->msg), "Interface %s is down - setting it up ...", conf_ifname());
+				pthread_mutex_unlock(&sr->mutex);
+
 				if (if_set_up(conf_ifname()) < 0)
 					err_sys("Can not bring up interface '%s'", conf_ifname());
 				break;
 			}
 			/* fall through */
 		default:
-			snprintf(sr->msg, sizeof(sr->msg),
-				 "Scan trigger failed on %s: %s", conf_ifname(), strerror(-ret));
+			snprintf(sr->msg, sizeof(sr->msg), "Scan trigger failed on %s: %s", conf_ifname(), strerror(-ret));
+			pthread_mutex_unlock(&sr->mutex);
 		}
 	} while (usleep(conf.stat_iv * 1000) == 0);
 
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