Re: [PATCH 4.19 044/321] mac80211: fix station inactive_time shortly after boot

Pavel Machek
2019-12-04T11:56:27Z

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On Tue 2019-12-03 23:31:50, Greg Kroah-Hartman wrote:
> From: Ahmed Zaki <anzaki@gmail.com>
>
> [ Upstream commit 285531f9e6774e3be71da6673d475ff1a088d675 ]
>
> 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.

I guess it fixes the message, but is it right fix?

> diff --git a/net/mac80211/sta_info.c b/net/mac80211/sta_info.c
> index f34202242d24d..507409e3fd39c 100644
> --- a/net/mac80211/sta_info.c
> +++ b/net/mac80211/sta_info.c
> @@ -2356,7 +2356,8 @@ 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;
> }

I mean, jiffies do wrapraound periodically, so eventually we'll have
sta->status_stats.last_ack == 0 even through it is not short after
boot, no?

Best regards,
Pavel
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

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