From: Johannes Berg <johannes.berg@intel.com>
Date: Tue, 10 Jul 2012 17:39:02 +0000 (+0200)
Subject: cfg80211: fix locking and lockdep complaints
X-Git-Url: http://git.lede-project.org./?a=commitdiff_plain;h=8e95ea49c94908cb10e698c5637d57f0fbdc796d;p=openwrt%2Fstaging%2Fblogic.git

cfg80211: fix locking and lockdep complaints

To call cfg80211_get_chan_state() we need to lock
the wdev, so we need to lock the wdev_iter mutex
in cfg80211_can_use_iftype_chan(). This needs to
use nested locking for lockdep.

Also, cfg80211_get_chan_state() doesn't actually
use the rdev, so remove that completely including
the lock assertion that isn't needed.

Reported-by: Eliad Peller <eliad@wizery.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
---

diff --git a/net/wireless/chan.c b/net/wireless/chan.c
index 434c56b92c3c..1cc4b7cc7372 100644
--- a/net/wireless/chan.c
+++ b/net/wireless/chan.c
@@ -103,15 +103,13 @@ int cfg80211_set_monitor_channel(struct cfg80211_registered_device *rdev,
 }
 
 void
-cfg80211_get_chan_state(struct cfg80211_registered_device *rdev,
-		        struct wireless_dev *wdev,
+cfg80211_get_chan_state(struct wireless_dev *wdev,
 		        struct ieee80211_channel **chan,
 		        enum cfg80211_chan_mode *chanmode)
 {
 	*chan = NULL;
 	*chanmode = CHAN_MODE_UNDEFINED;
 
-	ASSERT_RDEV_LOCK(rdev);
 	ASSERT_WDEV_LOCK(wdev);
 
 	if (!netif_running(wdev->netdev))
diff --git a/net/wireless/core.h b/net/wireless/core.h
index eae5a25a1691..bac97da751df 100644
--- a/net/wireless/core.h
+++ b/net/wireless/core.h
@@ -463,8 +463,7 @@ cfg80211_can_use_chan(struct cfg80211_registered_device *rdev,
 }
 
 void
-cfg80211_get_chan_state(struct cfg80211_registered_device *rdev,
-		        struct wireless_dev *wdev,
+cfg80211_get_chan_state(struct wireless_dev *wdev,
 		        struct ieee80211_channel **chan,
 		        enum cfg80211_chan_mode *chanmode);
 
diff --git a/net/wireless/util.c b/net/wireless/util.c
index f7a0647bde9a..26f8cd30f712 100644
--- a/net/wireless/util.c
+++ b/net/wireless/util.c
@@ -1059,7 +1059,16 @@ int cfg80211_can_use_iftype_chan(struct cfg80211_registered_device *rdev,
 		if (rdev->wiphy.software_iftypes & BIT(wdev_iter->iftype))
 			continue;
 
-		cfg80211_get_chan_state(rdev, wdev_iter, &ch, &chmode);
+		/*
+		 * We may be holding the "wdev" mutex, but now need to lock
+		 * wdev_iter. This is OK because once we get here wdev_iter
+		 * is not wdev (tested above), but we need to use the nested
+		 * locking for lockdep.
+		 */
+		mutex_lock_nested(&wdev_iter->mtx, 1);
+		__acquire(wdev_iter->mtx);
+		cfg80211_get_chan_state(wdev_iter, &ch, &chmode);
+		wdev_unlock(wdev_iter);
 
 		switch (chmode) {
 		case CHAN_MODE_UNDEFINED: