cfg80211: vastly simplify locking

Virtually all code paths in cfg80211 already (need to) hold
the RTNL. As such, there's little point in having another
four mutexes for various parts of the code, they just cause
lock ordering issues (and much of the time, the RTNL and a
few of the others need thus be held.)

Simplify all this by getting rid of the extra four mutexes
and just use the RTNL throughout. Only a few code changes
were needed to do this and we can get rid of a work struct
for bonus points.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>

1 files changed, 4 insertions, 22 deletions

diff --git a/net/wireless/sme.c b/net/wireless/sme.c
index 3ed35c345cae..4dbf31407a56 100644
--- a/net/wireless/sme.c
+++ b/net/wireless/sme.c
@@ -43,35 +43,29 @@ static bool cfg80211_is_all_idle(void)
         struct wireless_dev *wdev;
         bool is_all_idle = true;
 
-        mutex_lock(&cfg80211_mutex);
-
         /*
          * All devices must be idle as otherwise if you are actively
          * scanning some new beacon hints could be learned and would
          * count as new regulatory hints.
          */
         list_for_each_entry(rdev, &cfg80211_rdev_list, list) {
-                cfg80211_lock_rdev(rdev);
                 list_for_each_entry(wdev, &rdev->wdev_list, list) {
                         wdev_lock(wdev);
                         if (wdev->sme_state != CFG80211_SME_IDLE)
                                 is_all_idle = false;
                         wdev_unlock(wdev);
                 }
-                cfg80211_unlock_rdev(rdev);
         }
 
-        mutex_unlock(&cfg80211_mutex);
-
         return is_all_idle;
 }
 
 static void disconnect_work(struct work_struct *work)
 {
-        if (!cfg80211_is_all_idle())
-                return;
-
-        regulatory_hint_disconnect();
+        rtnl_lock();
+        if (cfg80211_is_all_idle())
+                regulatory_hint_disconnect();
+        rtnl_unlock();
 }
 
 static DECLARE_WORK(cfg80211_disconnect_work, disconnect_work);
@@ -85,7 +79,6 @@ static int cfg80211_conn_scan(struct wireless_dev *wdev)
         ASSERT_RTNL();
         ASSERT_RDEV_LOCK(rdev);
         ASSERT_WDEV_LOCK(wdev);
-        lockdep_assert_held(&rdev->sched_scan_mtx);
 
         if (rdev->scan_req)
                 return -EBUSY;
@@ -226,9 +219,6 @@ void cfg80211_conn_work(struct work_struct *work)
         u8 bssid_buf[ETH_ALEN], *bssid = NULL;
 
         rtnl_lock();
-        cfg80211_lock_rdev(rdev);
-        mutex_lock(&rdev->devlist_mtx);
-        mutex_lock(&rdev->sched_scan_mtx);
 
         list_for_each_entry(wdev, &rdev->wdev_list, list) {
                 if (!wdev->netdev)
@@ -256,9 +246,6 @@ void cfg80211_conn_work(struct work_struct *work)
                 wdev_unlock(wdev);
         }
 
-        mutex_unlock(&rdev->sched_scan_mtx);
-        mutex_unlock(&rdev->devlist_mtx);
-        cfg80211_unlock_rdev(rdev);
         rtnl_unlock();
 }
 
@@ -931,14 +918,9 @@ int cfg80211_connect(struct cfg80211_registered_device *rdev,
 {
         int err;
 
-        mutex_lock(&rdev->devlist_mtx);
-        /* might request scan - scan_mtx -> wdev_mtx dependency */
-        mutex_lock(&rdev->sched_scan_mtx);
         wdev_lock(dev->ieee80211_ptr);
         err = __cfg80211_connect(rdev, dev, connect, connkeys, NULL);
         wdev_unlock(dev->ieee80211_ptr);
-        mutex_unlock(&rdev->sched_scan_mtx);
-        mutex_unlock(&rdev->devlist_mtx);
 
         return err;
 }