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Commit 8e95ea49 authored Jul 10, 2012 by Johannes Berg

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>

parent 2a9e6c58

net/wireless/chan.c

+1 −3

Original line number	Diff line number	Diff line
		@@ -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))

net/wireless/core.h

+1 −2

Original line number	Diff line number	Diff line
		@@ -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);

net/wireless/util.c

+10 −1

Original line number	Diff line number	Diff line
		@@ -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: