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, 17 insertions, 25 deletions

diff --git a/net/wireless/scan.c b/net/wireless/scan.c
index 2ce44a712f13..dd01b58fa78c 100644
--- a/net/wireless/scan.c
+++ b/net/wireless/scan.c
@@ -169,7 +169,7 @@ void ___cfg80211_scan_done(struct cfg80211_registered_device *rdev, bool leak)
         union iwreq_data wrqu;
 #endif
 
-        lockdep_assert_held(&rdev->sched_scan_mtx);
+        ASSERT_RTNL();
 
         request = rdev->scan_req;
 
@@ -230,9 +230,9 @@ void __cfg80211_scan_done(struct work_struct *wk)
         rdev = container_of(wk, struct cfg80211_registered_device,
                             scan_done_wk);
 
-        mutex_lock(&rdev->sched_scan_mtx);
+        rtnl_lock();
         ___cfg80211_scan_done(rdev, false);
-        mutex_unlock(&rdev->sched_scan_mtx);
+        rtnl_unlock();
 }
 
 void cfg80211_scan_done(struct cfg80211_scan_request *request, bool aborted)
@@ -241,6 +241,7 @@ void cfg80211_scan_done(struct cfg80211_scan_request *request, bool aborted)
         WARN_ON(request != wiphy_to_dev(request->wiphy)->scan_req);
 
         request->aborted = aborted;
+        request->notified = true;
         queue_work(cfg80211_wq, &wiphy_to_dev(request->wiphy)->scan_done_wk);
 }
 EXPORT_SYMBOL(cfg80211_scan_done);
@@ -255,7 +256,7 @@ void __cfg80211_sched_scan_results(struct work_struct *wk)
 
         request = rdev->sched_scan_req;
 
-        mutex_lock(&rdev->sched_scan_mtx);
+        rtnl_lock();
 
         /* we don't have sched_scan_req anymore if the scan is stopping */
         if (request) {
@@ -270,7 +271,7 @@ void __cfg80211_sched_scan_results(struct work_struct *wk)
                 nl80211_send_sched_scan_results(rdev, request->dev);
         }
 
-        mutex_unlock(&rdev->sched_scan_mtx);
+        rtnl_unlock();
 }
 
 void cfg80211_sched_scan_results(struct wiphy *wiphy)
@@ -289,9 +290,9 @@ void cfg80211_sched_scan_stopped(struct wiphy *wiphy)
 
         trace_cfg80211_sched_scan_stopped(wiphy);
 
-        mutex_lock(&rdev->sched_scan_mtx);
+        rtnl_lock();
         __cfg80211_stop_sched_scan(rdev, true);
-        mutex_unlock(&rdev->sched_scan_mtx);
+        rtnl_unlock();
 }
 EXPORT_SYMBOL(cfg80211_sched_scan_stopped);
 
@@ -300,7 +301,7 @@ int __cfg80211_stop_sched_scan(struct cfg80211_registered_device *rdev,
 {
         struct net_device *dev;
 
-        lockdep_assert_held(&rdev->sched_scan_mtx);
+        ASSERT_RTNL();
 
         if (!rdev->sched_scan_req)
                 return -ENOENT;
@@ -1043,21 +1044,19 @@ EXPORT_SYMBOL(cfg80211_unlink_bss);
 static struct cfg80211_registered_device *
 cfg80211_get_dev_from_ifindex(struct net *net, int ifindex)
 {
-        struct cfg80211_registered_device *rdev = ERR_PTR(-ENODEV);
+        struct cfg80211_registered_device *rdev;
         struct net_device *dev;
 
-        mutex_lock(&cfg80211_mutex);
+        ASSERT_RTNL();
+
         dev = dev_get_by_index(net, ifindex);
         if (!dev)
-                goto out;
-        if (dev->ieee80211_ptr) {
+                return ERR_PTR(-ENODEV);
+        if (dev->ieee80211_ptr)
                 rdev = wiphy_to_dev(dev->ieee80211_ptr->wiphy);
-                mutex_lock(&rdev->mtx);
-        } else
+        else
                 rdev = ERR_PTR(-ENODEV);
         dev_put(dev);
- out:
-        mutex_unlock(&cfg80211_mutex);
         return rdev;
 }
 
@@ -1083,7 +1082,6 @@ int cfg80211_wext_siwscan(struct net_device *dev,
         if (IS_ERR(rdev))
                 return PTR_ERR(rdev);
 
-        mutex_lock(&rdev->sched_scan_mtx);
         if (rdev->scan_req) {
                 err = -EBUSY;
                 goto out;
@@ -1190,9 +1188,7 @@ int cfg80211_wext_siwscan(struct net_device *dev,
                 dev_hold(dev);
         }
  out:
-        mutex_unlock(&rdev->sched_scan_mtx);
         kfree(creq);
-        cfg80211_unlock_rdev(rdev);
         return err;
 }
 EXPORT_SYMBOL_GPL(cfg80211_wext_siwscan);
@@ -1491,10 +1487,8 @@ int cfg80211_wext_giwscan(struct net_device *dev,
         if (IS_ERR(rdev))
                 return PTR_ERR(rdev);
 
-        if (rdev->scan_req) {
-                res = -EAGAIN;
-                goto out;
-        }
+        if (rdev->scan_req)
+                return -EAGAIN;
 
         res = ieee80211_scan_results(rdev, info, extra, data->length);
         data->length = 0;
@@ -1503,8 +1497,6 @@ int cfg80211_wext_giwscan(struct net_device *dev,
                 res = 0;
         }
 
- out:
-        cfg80211_unlock_rdev(rdev);
         return res;
 }
 EXPORT_SYMBOL_GPL(cfg80211_wext_giwscan);