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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Markus Theil <markus.theil@tu-ilmenau.de>,
        Johannes Berg <johannes.berg@intel.com>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 4.9 44/68] mac80211: mesh: restrict airtime metric to peered established plinks
Date:   Mon,  3 Feb 2020 16:19:40 +0000
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From: Markus Theil <markus.theil@tu-ilmenau.de>

[ Upstream commit 02a614499600af836137c3fbc4404cd96365fff2 ]

The following warning is triggered every time an unestablished mesh peer
gets dumped. Checks if a peer link is established before retrieving the
airtime link metric.

[ 9563.022567] WARNING: CPU: 0 PID: 6287 at net/mac80211/mesh_hwmp.c:345
               airtime_link_metric_get+0xa2/0xb0 [mac80211]
[ 9563.022697] Hardware name: PC Engines apu2/apu2, BIOS v4.10.0.3
[ 9563.022756] RIP: 0010:airtime_link_metric_get+0xa2/0xb0 [mac80211]
[ 9563.022838] Call Trace:
[ 9563.022897]  sta_set_sinfo+0x936/0xa10 [mac80211]
[ 9563.022964]  ieee80211_dump_station+0x6d/0x90 [mac80211]
[ 9563.023062]  nl80211_dump_station+0x154/0x2a0 [cfg80211]
[ 9563.023120]  netlink_dump+0x17b/0x370
[ 9563.023130]  netlink_recvmsg+0x2a4/0x480
[ 9563.023140]  ____sys_recvmsg+0xa6/0x160
[ 9563.023154]  ___sys_recvmsg+0x93/0xe0
[ 9563.023169]  __sys_recvmsg+0x7e/0xd0
[ 9563.023210]  do_syscall_64+0x4e/0x140
[ 9563.023217]  entry_SYSCALL_64_after_hwframe+0x44/0xa9

Signed-off-by: Markus Theil <markus.theil@tu-ilmenau.de>
Link: https://lore.kernel.org/r/20191203180644.70653-1-markus.theil@tu-ilmenau.de
[rewrite commit message]
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 net/mac80211/mesh_hwmp.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/net/mac80211/mesh_hwmp.c b/net/mac80211/mesh_hwmp.c
index b0acb2961e805..5f4c228b82e56 100644
--- a/net/mac80211/mesh_hwmp.c
+++ b/net/mac80211/mesh_hwmp.c
@@ -326,6 +326,9 @@ static u32 airtime_link_metric_get(struct ieee80211_local *local,
 	u32 tx_time, estimated_retx;
 	u64 result;
 
+	if (sta->mesh->plink_state != NL80211_PLINK_ESTAB)
+		return MAX_METRIC;
+
 	/* Try to get rate based on HW/SW RC algorithm.
 	 * Rate is returned in units of Kbps, correct this
 	 * to comply with airtime calculation units
-- 
2.20.1