From: Ahmed Zaki <anzaki@gmail.com>
Date: Thu, 31 Oct 2019 06:12:43 -0600
Subject: mac80211: fix station inactive_time shortly after boot
Git-commit: 285531f9e6774e3be71da6673d475ff1a088d675
Patch-mainline: 5.4-rc7
References: bnc#1151927 5.3.15

In the first 5 minutes after boot (time of INITIAL_JIFFIES),
ieee80211_sta_last_active() returns zero if last_ack is zero. This
leads to "inactive time" showing jiffies_to_msecs(jiffies).

 # iw wlan0 station get fc:ec:da:64:a6:dd
 Station fc:ec:da:64:a6:dd (on wlan0)
	inactive time:	4294894049 ms
	.
	.
	connected time:	70 seconds

Fix by returning last_rx if last_ack == 0.

Signed-off-by: Ahmed Zaki <anzaki@gmail.com>
Link: https://lore.kernel.org/r/20191031121243.27694-1-anzaki@gmail.com
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---
 net/mac80211/sta_info.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/net/mac80211/sta_info.c
+++ b/net/mac80211/sta_info.c
@@ -2455,7 +2455,8 @@ unsigned long ieee80211_sta_last_active(
 {
 	struct ieee80211_sta_rx_stats *stats = sta_get_last_rx_stats(sta);
 
-	if (time_after(stats->last_rx, sta->status_stats.last_ack))
+	if (!sta->status_stats.last_ack ||
+	    time_after(stats->last_rx, sta->status_stats.last_ack))
 		return stats->last_rx;
 	return sta->status_stats.last_ack;
 }