Patch "mac80211: don't send SMPS action frame in AP mode when not needed" has been added to the 4.9-stable tree

This is a note to let you know that I've just added the patch titled

mac80211: don't send SMPS action frame in AP mode when not needed

to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:

     mac80211-don-t-send-smps-action-frame-in-ap-mode-when-not-needed.patch

and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Emmanuel Grumbach <[email protected]>
Date: Sat, 10 Jun 2017 13:52:45 +0300
Subject: mac80211: don't send SMPS action frame in AP mode when not needed

From: Emmanuel Grumbach <[email protected]>

commit b3dd8279659f14f3624bb32559782d699fa6f7d1 upstream.

mac80211 allows to modify the SMPS state of an AP both, when it is started, and after it has been started. Such a change will trigger an action frame to all the peers that are currently connected, and will be remembered so that new peers will get notified as soon as they connect (since the SMPS setting in the beacon may not be the right one).

This means that we need to remember the SMPS state currently requested as well as the SMPS state that was configured initially (and advertised in the beacon). The former is bss->req_smps and the latter is sdata->smps_mode.

Initially, the AP interface could only be started with SMPS_OFF, which means that sdata->smps_mode was SMPS_OFF always. Later, a nl80211 API was added to be able to start an AP with a different AP mode. That code forgot to update bss->req_smps and because of that, if the AP interface was started with SMPS_DYNAMIC, we had:
sdata->smps_mode = SMPS_DYNAMIC
bss->req_smps = SMPS_OFF

That configuration made mac80211 think it needs to fire off an action frame to any new station connecting to the AP in order to let it know that the actual SMPS configuration is SMPS_OFF.

Fix that by properly setting bss->req_smps in
ieee80211_start_ap.

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

@@ -865,6 +865,8 @@ static int ieee80211_start_ap(struct wip
 	default:
 		return -EINVAL;
 	}
+	sdata->u.ap.req_smps = sdata->smps_mode;
+
 	sdata->needed_rx_chains = sdata->local->rx_chains;
 
 	mutex_lock(&local->mtx);

Patches currently in stable-queue which might be from [email protected] are

queue-4.9/mac80211-don-t-send-smps-action-frame-in-ap-mode-when-not-needed.patch queue-4.9/mac80211-don-t-look-at-the-pm-bit-of-bar-frames.patch