linux-kernel - [PATCH 4.9 052/109] mac80211: calculate min channel width correctly

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Message-Id: <20171207125640.696843516@linuxfoundation.org>
Date:   Thu,  7 Dec 2017 13:56:36 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Johannes Berg <johannes.berg@...el.com>,
        Sasha Levin <alexander.levin@...izon.com>
Subject: [PATCH 4.9 052/109] mac80211: calculate min channel width correctly

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Johannes Berg <johannes.berg@...el.com>

[ Upstream commit 96aa2e7cf126773b16c6c19b7474a8a38d3c707e ]

In the current minimum chandef code there's an issue in that the
recalculation can happen after rate control is initialized for a
station that has a wider bandwidth than the current chanctx, and
then rate control can immediately start using those higher rates
which could cause problems.

Observe that first of all that this problem is because we don't
take non-associated and non-uploaded stations into account. The
restriction to non-associated is quite pointless and is one of
the causes for the problem described above, since the rate init
will happen before the station is set to associated; no frames
could actually be sent until associated, but the rate table can
already contain higher rates and that might cause problems.

Also, rejecting non-uploaded stations is wrong, since the rate
control can select higher rates for those as well.

Secondly, it's then necessary to recalculate the minimal config
before initializing rate control, so that when rate control is
initialized, the higher rates are already available. This can be
done easily by adding the necessary function call in rate init.

Change-Id: Ib9bc02d34797078db55459d196993f39dcd43070
Signed-off-by: Johannes Berg <johannes.berg@...el.com>
Signed-off-by: Sasha Levin <alexander.levin@...izon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 net/mac80211/chan.c |    3 ---
 net/mac80211/rate.c |    2 ++
 2 files changed, 2 insertions(+), 3 deletions(-)

--- a/net/mac80211/chan.c
+++ b/net/mac80211/chan.c
@@ -231,9 +231,6 @@ ieee80211_get_max_required_bw(struct iee
 		    !(sta->sdata->bss && sta->sdata->bss == sdata->bss))
 			continue;

-		if (!sta->uploaded || !test_sta_flag(sta, WLAN_STA_ASSOC))
-			continue;
-
 		max_bw = max(max_bw, ieee80211_get_sta_bw(&sta->sta));
 	}
 	rcu_read_unlock();
--- a/net/mac80211/rate.c
+++ b/net/mac80211/rate.c
@@ -40,6 +40,8 @@ void rate_control_rate_init(struct sta_i

 	ieee80211_sta_set_rx_nss(sta);

+	ieee80211_recalc_min_chandef(sta->sdata);
+
 	if (!ref)
 		return;