2019-10-31 12:16:26

by Ahmed Zaki

Subject: [PATCH v2] mac80211: fix insane values that sometimes appear in inactive_time

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 <[email protected]>
---
net/mac80211/sta_info.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/mac80211/sta_info.c b/net/mac80211/sta_info.c
index bd11fef2139f..428866ff7c0a 100644
--- a/net/mac80211/sta_info.c
+++ b/net/mac80211/sta_info.c
@@ -2457,7 +2457,8 @@ unsigned long ieee80211_sta_last_active(struct sta_info *sta)
{
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;
}
--
2.17.1

2019-10-31 12:24:37

by Johannes Berg

Subject: Re: [PATCH v2] mac80211: fix insane values that sometimes appear in inactive_time

On Thu, 2019-10-31 at 06:12 -0600, Ahmed Zaki wrote:
> 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 <[email protected]>

Thanks for the updates :)

> - 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;

The indentation is still wrong :)

I guess I could fix that too.

johannes