cfg80211: fix locking for SIWFREQ

"cfg80211: validate channel settings across interfaces"
contained a locking bug -- in the managed-mode SIWFREQ
call it would end up running into a lock recursion.

This fixes it by not checking that particular interface
for a channel that it needs to stay on, which is as it
should be as that's the interface we're setting the
channel for.

Reported-by: Reinette Chatre <reinette.chatre@intel.com>
Reported-by: Kalle Valo <kalle.valo@iki.fi>
Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Tested-by: Kalle Valo <kalle.valo@iki.fi>
Tested-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

net/wireless/chan.c

@@ -42,13 +42,14 @@ rdev_fixed_channel(struct cfg80211_registered_device *rdev,
 }
 
 int rdev_set_freq(struct cfg80211_registered_device *rdev,
+		  struct wireless_dev *for_wdev,
 		  int freq, enum nl80211_channel_type channel_type)
 {
 	struct ieee80211_channel *chan;
 	struct ieee80211_sta_ht_cap *ht_cap;
 	int result;
 
-	if (rdev_fixed_channel(rdev, NULL))
+	if (rdev_fixed_channel(rdev, for_wdev))
 		return -EBUSY;
 
 	if (!rdev->ops->set_channel)

net/wireless/core.h

@@ -374,6 +374,7 @@ struct ieee80211_channel *
 rdev_fixed_channel(struct cfg80211_registered_device *rdev,
 		   struct wireless_dev *for_wdev);
 int rdev_set_freq(struct cfg80211_registered_device *rdev,
+		  struct wireless_dev *for_wdev,
 		  int freq, enum nl80211_channel_type channel_type);
 
 #endif /* __NET_WIRELESS_CORE_H */

net/wireless/nl80211.c

@@ -721,7 +721,7 @@ static int nl80211_set_wiphy(struct sk_buff *skb, struct genl_info *info)
 		freq = nla_get_u32(info->attrs[NL80211_ATTR_WIPHY_FREQ]);
 
 		mutex_lock(&rdev->devlist_mtx);
-		result = rdev_set_freq(rdev, freq, channel_type);
+		result = rdev_set_freq(rdev, NULL, freq, channel_type);
 		mutex_unlock(&rdev->devlist_mtx);
 		if (result)
 			goto bad_res;

net/wireless/wext-compat.c

@@ -766,7 +766,7 @@ int cfg80211_wext_siwfreq(struct net_device *dev,
 		if (freq == 0)
 			return -EINVAL;
 		mutex_lock(&rdev->devlist_mtx);
-		err = rdev_set_freq(rdev, freq, NL80211_CHAN_NO_HT);
+		err = rdev_set_freq(rdev, NULL, freq, NL80211_CHAN_NO_HT);
 		mutex_unlock(&rdev->devlist_mtx);
 		return err;
 	}

net/wireless/wext-sme.c

@@ -106,7 +106,7 @@ int cfg80211_mgd_wext_siwfreq(struct net_device *dev,
 
 	/* SSID is not set, we just want to switch channel */
 	if (chan && !wdev->wext.connect.ssid_len) {
-		err = rdev_set_freq(rdev, freq, NL80211_CHAN_NO_HT);
+		err = rdev_set_freq(rdev, wdev, freq, NL80211_CHAN_NO_HT);
 		goto out;
 	}