From 4f5a5866aa4dccf42b2fa1cdecf372025a3e86cc Mon Sep 17 00:00:00 2001 From: Liang Li Date: Thu, 2 Aug 2012 18:55:41 -0400 Subject: [PATCH] cfg80211: fix interface combinations check for ADHOC(IBSS) partial of commit 8e8b41f9d8c8e63fc92f899ace8da91a490ac573 upstream. 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[] and hence we'll get -EBUSY when we bring up a ADHOC wlan with commands similar to: # iwconfig wlan0 mode ad-hoc && ifconfig wlan0 up In commit 8e8b41f9d8c8e ("cfg80211: enforce lack of interface combinations"), the change below fixes the issue: if (total == 1) return 0; But it also introduces other dependencies 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 And the purpose of the 'if (total == 1)' is to cover the specific use case (IBSS, adhoc) that was mentioned above. So we just pick the specific part out from 8e8b41f9d8c8e here. Doing so 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 Signed-off-by: Paul Gortmaker Signed-off-by: Greg Kroah-Hartman --- net/wireless/util.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/net/wireless/util.c b/net/wireless/util.c index 4d69149eef2c..18e22bef386d 100644 --- a/net/wireless/util.c +++ b/net/wireless/util.c @@ -975,6 +975,9 @@ int cfg80211_can_change_interface(struct cfg80211_registered_device *rdev, } mutex_unlock(&rdev->devlist_mtx); + if (total == 1) + return 0; + for (i = 0; i < rdev->wiphy.n_iface_combinations; i++) { const struct ieee80211_iface_combination *c; struct ieee80211_iface_limit *limits; -- 2.39.5