[PATCH 0/1] sta_info: fix insane values in iw sta dump "inactive time"

[PATCH 0/1] sta_info: fix insane values in iw sta dump "inactive time"

[Ahmed Zaki]

While working on an IBSS network with ath10k-ct, the iw station dump
shows insanly high values in the "inactive time". The values are
clearly the initial jiifies of the system.

Debugging showed that this happens when the ieee80211_sta_last_active
is called while last_ack == 0. In this case, it returns zero and the
inactive time shows the system jiffies. This continues until the
jiffies wrap back to zero (about 5 minutes).

Ahmed Zaki (1):
  sta_info: fix insane values in iw sta dump "inactive time"

 net/mac80211/sta_info.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

-- 
2.17.1

[PATCH 1/1] sta_info: fix insane values in iw sta dump "inactive time"

[Ahmed Zaki]

In the first 5 mins after boot (initial jiffies),
ieee80211_sta_last_active() returns zero in case last_ack is zero. This
leads to insane values appearing in "inactive time".

Fix by returning last_rx if last_ack == 0.
---
 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

Re: [PATCH 1/1] sta_info: fix insane values in iw sta dump "inactive time"

[Johannes Berg]

On Wed, 2019-10-30 at 15:31 -0600, Ahmed Zaki wrote:
> In the first 5 mins after boot (initial jiffies),
> ieee80211_sta_last_active() returns zero in case last_ack is zero. This
> leads to insane values appearing in "inactive time".
> 
> Fix by returning last_rx if last_ack == 0.

Please read

https://wireless.wiki.kernel.org/en/developers/Documentation/SubmittingPatches

johannes