cfg80211: fix locking in nl80211_set_wiphy

Luis reports that there's a circular locking dependency;
this is because cfg80211_dev_rename() will acquire the
cfg80211_mutex while the device mutex is held, while
this normally is done the other way around. The solution
is to open-code the device-getting in nl80211_set_wiphy
and require holding the mutex around cfg80211_dev_rename
rather than acquiring it within.

Also fix a bug -- rtnl locking is expected by drivers so
we need to provide it.

Reported-by: Luis R. Rodriguez <lrodriguez@atheros.com>
Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 3 insertions, 0 deletions

diff --git a/net/wireless/core.h b/net/wireless/core.h
index 97a6fd8b2b03..d43daa236ef9 100644
--- a/net/wireless/core.h
+++ b/net/wireless/core.h
@@ -99,6 +99,9 @@ struct cfg80211_internal_bss {
 struct cfg80211_registered_device *cfg80211_drv_by_wiphy_idx(int wiphy_idx);
 int get_wiphy_idx(struct wiphy *wiphy);
 
+struct cfg80211_registered_device *
+__cfg80211_drv_from_info(struct genl_info *info);
+
 /*
  * This function returns a pointer to the driver
  * that the genl_info item that is passed refers to.