[PATCH 5.11 073/210] mac80211: fix time-is-after bug in mlme

Greg Kroah-Hartman
2021-04-12T09:31:06Z

From: Ben Greear <greearb@candelatech.com>

commit 7d73cd946d4bc7d44cdc5121b1c61d5d71425dea upstream.

The incorrect timeout check caused probing to happen when it did
not need to happen. This in turn caused tx performance drop
for around 5 seconds in ath10k-ct driver. Possibly that tx drop
is due to a secondary issue, but fixing the probe to not happen
when traffic is running fixes the symptom.

Signed-off-by: Ben Greear <greearb@candelatech.com>
Fixes: 9abf4e49830d ("mac80211: optimize station connection monitor")
Acked-by: Felix Fietkau <nbd@nbd.name>
Link: https://lore.kernel.org/r/20210330230749.14097-1-greearb@candelatech.com
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/mac80211/mlme.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)

--- a/net/mac80211/mlme.c
+++ b/net/mac80211/mlme.c
@@ -4707,7 +4707,10 @@ static void ieee80211_sta_conn_mon_timer
timeout = sta->rx_stats.last_rx;
timeout += IEEE80211_CONNECTION_IDLE_TIME;

- if (time_is_before_jiffies(timeout)) {
+ /* If timeout is after now, then update timer to fire at
+ * the later date, but do not actually probe at this time.
+ */
+ if (time_is_after_jiffies(timeout)) {
mod_timer(&ifmgd->conn_mon_timer, round_jiffies_up(timeout));
return;
}