From: Liang Li <[email protected]>
As part of commit 463454b5dbd8 ("cfg80211: fix interface
combinations check"), this extra check was introduced:
if ((all_iftypes & used_iftypes) != used_iftypes)
goto cont;
However, most wireless NIC drivers did not advertise ADHOC in
wiphy.iface_combinations[i].limits[] hence we'll get -EBUSY when
we bring up a ADHOC wlan by commands similar to:
# iwconfig wlan0 mode ad-hoc && ifconfig wlan0 up
In commit 8e8b41f9d8c8e ("cfg80211: enforce lack of interface
combinations"), the change below happens to fix the issue:
if (total == 1)
return 0;
But it also introduces other dependencies, at least for stable.
For example, a full cherry pick of 8e8b41f9d8c8e would introduce
additional regressions unless we also start cherry picking driver
specific fixes like the following:
9b4760e ath5k: add possible wiphy interface combinations
1ae2fc2 mac80211_hwsim: advertise interface combinations
20c8e8d ath9k: add possible wiphy interface combinations
It seems like we should add an exception for NL80211_IFTYPE_ADHOC, since
it is a kind of 'basic' mode, being supported by almost all wifi cards
but currently most drivers don't advertise it at all. So making the
NL80211_IFTYPE_ADHOC a part of all_iftypes seems reasonable.
Doing so also gives stable kernels a way to fix the change introduced
by 463454b5dbd8, without having to make cherry picks specific to
various NIC drivers.
Signed-off-by: Liang Li <[email protected]>
Signed-off-by: Paul Gortmaker <[email protected]>
---
net/wireless/util.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/net/wireless/util.c b/net/wireless/util.c
index 26f8cd3..4a4749c 100644
--- a/net/wireless/util.c
+++ b/net/wireless/util.c
@@ -1129,6 +1129,8 @@ int cfg80211_can_use_iftype_chan(struct
cfg80211_registered_device *rdev,
}
}
+ all_iftypes |= BIT(NL80211_IFTYPE_ADHOC);
+
/*
* Finally check that all iftypes that we're currently
* using are actually part of this combination. If they
--
1.7.11.1
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