* handle_driver_events() kept the sDriversListLock locked over the whole

time. But since this is also locked from within the driver/directory watcher
  (with the node monitor lock held), and handle_driver_events() could cause
  node monitoring updates, the locking order could be reverted, causing a
  deadlock (I just ran into).


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@32152 a95241bf-73f2-0310-859d-f6bbb57e9c96

src/system/kernel/device_manager/legacy_drivers.cpp

@@ -196,6 +196,7 @@ static int32 sDriverEvents;
 static EntryList sDriversToAdd;
 static EntryList sDriversToRemove;
 static mutex sDriversListLock = MUTEX_INITIALIZER("driversList");
+	// inner lock, protects the sDriversToAdd/sDriversToRemove lists only
 static DirectoryWatcher sDirectoryWatcher;
 static DirectoryNodeHash sDirectoryNodeHash;
 static recursive_lock sLock;
@@ -641,14 +642,19 @@ handle_driver_events(void */*_fs*/, int /*iteration*/)
 
 	// something happened, let's see what it was
 
-	RecursiveLocker locker(sLock);
-	MutexLocker _(sDriversListLock);
+	RecursiveLocker _(sLock);
+
+	// Add new drivers
 
 	while (true) {
+		MutexLocker listLocker(sDriversListLock);
+
 		path_entry* path = sDriversToAdd.RemoveHead();
 		if (path == NULL)
 			break;
 
+		listLocker.Unlock();
+
 		legacy_driver* driver = (legacy_driver*)hash_lookup(sDriverHash,
 			get_leaf(path->path));
 		if (driver == NULL)
@@ -657,11 +663,18 @@ handle_driver_events(void */*_fs*/, int /*iteration*/)
 			driver->binary_updated = true;
 		delete path;
 	}
+
+	// Mark removed drivers as updated
+
 	while (true) {
+		MutexLocker listLocker(sDriversListLock);
+
 		path_entry* path = sDriversToRemove.RemoveHead();
 		if (path == NULL)
 			break;
 
+		listLocker.Unlock();
+
 		legacy_driver* driver = (legacy_driver*)hash_lookup(sDriverHash,
 			get_leaf(path->path));
 		if (driver != NULL && get_priority(path->path) >= driver->priority)
@@ -669,6 +682,8 @@ handle_driver_events(void */*_fs*/, int /*iteration*/)
 		delete path;
 	}
 
+	// Reload updated drivers
+
 	hash_iterator iterator;
 	hash_open(sDriverHash, &iterator);
 	legacy_driver *driver;