ipw2x00: age scan results on resume

Scanned BSS entries are timestamped with jiffies, which doesn't
increment across suspend and hibernate.  On resume, every BSS in the
scan list looks like it was scanned within the last 10 seconds,
irregardless of how long the machine was actually asleep.  Age scan
results on resume with the time spent during sleep so userspace has a
clue how old they really are.

Signed-off-by: Dan Williams <dcbw@redhat.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 17 insertions, 7 deletions

diff --git a/drivers/net/wireless/ipw2x00/libipw_wx.c b/drivers/net/wireless/ipw2x00/libipw_wx.c
index dfbadb3b9bd..3c0812db030 100644
--- a/drivers/net/wireless/ipw2x00/libipw_wx.c
+++ b/drivers/net/wireless/ipw2x00/libipw_wx.c
@@ -43,6 +43,16 @@ static const char *ieee80211_modes[] = {
 	"?", "a", "b", "ab", "g", "ag", "bg", "abg"
 };
 
+static inline unsigned int elapsed_jiffies_msecs(unsigned long start)
+{
+	unsigned long end = jiffies;
+
+	if (end >= start)
+		return jiffies_to_msecs(end - start);
+
+	return jiffies_to_msecs(end + (MAX_JIFFY_OFFSET - start) + 1);
+}
+
 #define MAX_CUSTOM_LEN 64
 static char *ieee80211_translate_scan(struct ieee80211_device *ieee,
 				      char *start, char *stop,
@@ -216,8 +226,8 @@ static char *ieee80211_translate_scan(struct ieee80211_device *ieee,
 	iwe.cmd = IWEVCUSTOM;
 	p = custom;
 	p += snprintf(p, MAX_CUSTOM_LEN - (p - custom),
-		      " Last beacon: %dms ago",
-		      jiffies_to_msecs(jiffies - network->last_scanned));
+		      " Last beacon: %ums ago",
+		      elapsed_jiffies_msecs(network->last_scanned));
 	iwe.u.data.length = p - custom;
 	if (iwe.u.data.length)
 		start = iwe_stream_add_point(info, start, stop, &iwe, custom);
@@ -277,15 +287,15 @@ int ieee80211_wx_get_scan(struct ieee80211_device *ieee,
 		    time_after(network->last_scanned + ieee->scan_age, jiffies))
 			ev = ieee80211_translate_scan(ieee, ev, stop, network,
 						      info);
-		else
+		else {
 			IEEE80211_DEBUG_SCAN("Not showing network '%s ("
-					     "%pM)' due to age (%dms).\n",
+					     "%pM)' due to age (%ums).\n",
 					     print_ssid(ssid, network->ssid,
 							 network->ssid_len),
 					     network->bssid,
-					     jiffies_to_msecs(jiffies -
-							      network->
-							      last_scanned));
+					     elapsed_jiffies_msecs(
+					               network->last_scanned));
+		}
 	}
 
 	spin_unlock_irqrestore(&ieee->lock, flags);