svn commit: r251391 - head/sys/security/mac

[Alan Cox]

Author: alc
Date: Tue Jun  4 17:23:09 2013
New Revision: 251391
URL: http://svnweb.freebsd.org/changeset/base/251391

Log:
  Relax the vm object locking in mac_proc_vm_revoke_recurse().  A read lock
  suffices in one place.
  
  Sponsored by:	EMC / Isilon Storage Division

Modified:
  head/sys/security/mac/mac_process.c

Modified: head/sys/security/mac/mac_process.c
==============================================================================
--- head/sys/security/mac/mac_process.c	Tue Jun  4 17:08:26 2013	(r251390)
+++ head/sys/security/mac/mac_process.c	Tue Jun  4 17:23:09 2013	(r251391)
@@ -284,14 +284,14 @@ mac_proc_vm_revoke_recurse(struct thread
 		object = vme->object.vm_object;
 		if (object == NULL)
 			continue;
-		VM_OBJECT_WLOCK(object);
+		VM_OBJECT_RLOCK(object);
 		while ((backing_object = object->backing_object) != NULL) {
-			VM_OBJECT_WLOCK(backing_object);
+			VM_OBJECT_RLOCK(backing_object);
 			offset += object->backing_object_offset;
-			VM_OBJECT_WUNLOCK(object);
+			VM_OBJECT_RUNLOCK(object);
 			object = backing_object;
 		}
-		VM_OBJECT_WUNLOCK(object);
+		VM_OBJECT_RUNLOCK(object);
 		/*
 		 * At the moment, vm_maps and objects aren't considered by
 		 * the MAC system, so only things with backing by a normal