diff -crB intel-driver-1.0.18/src/gen6_mfd.c intel-driver-1.0.18_patch/src/gen6_mfd.c
*** intel-driver-1.0.18/src/gen6_mfd.c	Mon May 28 23:22:14 2012
--- intel-driver-1.0.18_patch/src/gen6_mfd.c	Fri Oct 12 12:30:28 2012
***************
*** 40,45 ****
--- 40,47 ----
  
  #include "gen6_mfd.h"
  
+ pthread_mutex_t free_avc_surface_lock;
+ 
  static const uint32_t zigzag_direct[64] = {
      0,   1,  8, 16,  9,  2,  3, 10,
      17, 24, 32, 25, 18, 11,  4,  5,
***************
*** 170,179 ****
  static void 
  gen6_mfd_free_avc_surface(void **data)
  {
-     struct gen6_avc_surface *gen6_avc_surface = *data;
  
      if (!gen6_avc_surface)
!         return;
  
      dri_bo_unreference(gen6_avc_surface->dmv_top);
      gen6_avc_surface->dmv_top = NULL;
--- 172,189 ----
  static void 
  gen6_mfd_free_avc_surface(void **data)
  {
  
+     struct gen6_avc_surface *gen6_avc_surface;
+ 
+     pthread_mutex_lock(&free_avc_surface_lock);
+ 
+     gen6_avc_surface = *data;
      if (!gen6_avc_surface)
!     {
!       pthread_mutex_unlock(&free_avc_surface_lock);
!       return;
!     }
! 
  
      dri_bo_unreference(gen6_avc_surface->dmv_top);
      gen6_avc_surface->dmv_top = NULL;
***************
*** 182,187 ****
--- 192,200 ----
  
      free(gen6_avc_surface);
      *data = NULL;
+ 
+     pthread_mutex_unlock(&free_avc_surface_lock);
+ 
  }
  
  static void