From d22828f716fba0c63522101bd18f9660db17b364 Mon Sep 17 00:00:00 2001
From: José Fonseca <jfonseca@vmware.com>
Date: Tue, 16 Jun 2009 21:30:59 +0100
Subject: wgl: Factor out some repetitive code into inline functions.

---
 .../state_trackers/wgl/shared/stw_context.c        | 57 +++++++++++-----------
 1 file changed, 28 insertions(+), 29 deletions(-)

(limited to 'src/gallium/state_trackers/wgl/shared')

diff --git a/src/gallium/state_trackers/wgl/shared/stw_context.c b/src/gallium/state_trackers/wgl/shared/stw_context.c
index 662b5fbcd2a..1c217699ab1 100644
--- a/src/gallium/state_trackers/wgl/shared/stw_context.c
+++ b/src/gallium/state_trackers/wgl/shared/stw_context.c
@@ -47,6 +47,23 @@
 #include "stw_context.h"
 #include "stw_tls.h"
 
+
+static INLINE struct stw_context *
+stw_context(GLcontext *glctx)
+{
+   if(!glctx)
+      return NULL;
+   assert(glctx->DriverCtx);
+   return (struct stw_context *)glctx->DriverCtx;
+}
+
+static INLINE struct stw_context *
+stw_current_context(void)
+{
+   GET_CURRENT_CONTEXT( glctx );
+   return stw_context(glctx);
+}
+
 BOOL
 stw_copy_context(
    UINT_PTR hglrcSrc,
@@ -194,11 +211,10 @@ stw_delete_context(
    pipe_mutex_unlock( stw_dev->mutex );
 
    if (ctx) {
-      GLcontext *glctx = ctx->st->ctx;
-      GET_CURRENT_CONTEXT( glcurctx );
-
+      struct stw_context *curctx = stw_current_context();
+      
       /* Unbind current if deleting current context. */
-      if (glcurctx == glctx)
+      if (curctx == ctx)
          st_make_current( NULL, NULL, NULL );
 
       st_destroy_context(ctx->st);
@@ -230,13 +246,8 @@ stw_release_context(
     * current for this thread.  We should check that and return False
     * if not the case.
     */
-   {
-      GLcontext *glctx = ctx->st->ctx;
-      GET_CURRENT_CONTEXT( glcurctx );
-
-      if (glcurctx != glctx)
-         return FALSE;
-   }
+   if (ctx != stw_current_context())
+      return FALSE;
 
    if (stw_make_current( NULL, 0 ) == FALSE)
       return FALSE;
@@ -248,14 +259,9 @@ stw_release_context(
 UINT_PTR
 stw_get_current_context( void )
 {
-   GET_CURRENT_CONTEXT( glcurctx );
    struct stw_context *ctx;
 
-   if(!glcurctx)
-      return 0;
-   
-   ctx = (struct stw_context *)glcurctx->DriverCtx;
-   assert(ctx);
+   ctx = stw_current_context();
    if(!ctx)
       return 0;
    
@@ -265,14 +271,9 @@ stw_get_current_context( void )
 HDC
 stw_get_current_dc( void )
 {
-   GET_CURRENT_CONTEXT( glcurctx );
    struct stw_context *ctx;
 
-   if(!glcurctx)
-      return NULL;
-   
-   ctx = (struct stw_context *)glcurctx->DriverCtx;
-   assert(ctx);
+   ctx = stw_current_context();
    if(!ctx)
       return NULL;
    
@@ -284,19 +285,17 @@ stw_make_current(
    HDC hdc,
    UINT_PTR hglrc )
 {
+   struct stw_context *curctx;
    struct stw_context *ctx;
-   GET_CURRENT_CONTEXT( glcurctx );
    struct stw_framebuffer *fb;
 
    if (!stw_dev)
       goto fail;
 
-   if (glcurctx != NULL) {
-      struct stw_context *curctx;
-      curctx = (struct stw_context *) glcurctx->DriverCtx;
-
+   curctx = stw_current_context();
+   if (curctx != NULL) {
       if (curctx->hglrc != hglrc)
-	 st_flush(glcurctx->st, PIPE_FLUSH_RENDER_CACHE, NULL);
+	 st_flush(curctx->st, PIPE_FLUSH_RENDER_CACHE, NULL);
       
       /* Return if already current. */
       if (curctx->hglrc == hglrc && curctx->hdc == hdc)
-- 
cgit v1.2.3


From 4b4855c717e839a9ee6353604558543473c020c9 Mon Sep 17 00:00:00 2001
From: José Fonseca <jfonseca@vmware.com>
Date: Wed, 17 Jun 2009 19:24:51 +0100
Subject: wgl: Move all thread related code together.

Not only for cosmetic reasons, but also because we need to set the
SetWindowsHookEx hook for threads created before the DllMain is called
(threads for each we don't get the DLL_THREAD_ATTACH notification).
---
 src/gallium/state_trackers/wgl/shared/stw_device.c |  9 +-----
 .../state_trackers/wgl/shared/stw_framebuffer.c    | 37 +---------------------
 .../state_trackers/wgl/shared/stw_framebuffer.h    |  6 ----
 src/gallium/state_trackers/wgl/shared/stw_tls.c    | 33 ++++++++++++++-----
 src/gallium/state_trackers/wgl/shared/stw_tls.h    |  6 ++++
 5 files changed, 33 insertions(+), 58 deletions(-)

(limited to 'src/gallium/state_trackers/wgl/shared')

diff --git a/src/gallium/state_trackers/wgl/shared/stw_device.c b/src/gallium/state_trackers/wgl/shared/stw_device.c
index 1a6b29807d7..070ffcb3ca1 100644
--- a/src/gallium/state_trackers/wgl/shared/stw_device.c
+++ b/src/gallium/state_trackers/wgl/shared/stw_device.c
@@ -133,20 +133,13 @@ error1:
 boolean
 stw_init_thread(void)
 {
-   if (!stw_tls_init_thread())
-      return FALSE;
-
-   if (!stw_framebuffer_init_thread())
-      return FALSE;
-
-   return TRUE;
+   return stw_tls_init_thread();
 }
 
 
 void
 stw_cleanup_thread(void)
 {
-   stw_framebuffer_cleanup_thread();
    stw_tls_cleanup_thread();
 }
 
diff --git a/src/gallium/state_trackers/wgl/shared/stw_framebuffer.c b/src/gallium/state_trackers/wgl/shared/stw_framebuffer.c
index 58f18303191..88043859ce4 100644
--- a/src/gallium/state_trackers/wgl/shared/stw_framebuffer.c
+++ b/src/gallium/state_trackers/wgl/shared/stw_framebuffer.c
@@ -84,7 +84,7 @@ stw_framebuffer_destroy_locked(
  * @sa http://msdn.microsoft.com/en-us/library/ms644975(VS.85).aspx
  * @sa http://msdn.microsoft.com/en-us/library/ms644960(VS.85).aspx
  */
-static LRESULT CALLBACK
+LRESULT CALLBACK
 stw_call_window_proc(
    int nCode,
    WPARAM wParam,
@@ -423,38 +423,3 @@ stw_swap_layer_buffers(
 
    return FALSE;
 }
-
-
-boolean
-stw_framebuffer_init_thread(void)
-{
-   struct stw_tls_data *tls_data;
-   
-   tls_data = stw_tls_get_data();
-   if(!tls_data)
-      return FALSE;
-   
-   tls_data->hCallWndProcHook = SetWindowsHookEx(WH_CALLWNDPROC,
-                                                 stw_call_window_proc,
-                                                 NULL,
-                                                 GetCurrentThreadId());
-   if(tls_data->hCallWndProcHook == NULL)
-      return FALSE;
-   
-   return TRUE;
-}
-
-void
-stw_framebuffer_cleanup_thread(void)
-{
-   struct stw_tls_data *tls_data;
-   
-   tls_data = stw_tls_get_data();
-   if(!tls_data)
-      return;
-   
-   if(tls_data->hCallWndProcHook) {
-      UnhookWindowsHookEx(tls_data->hCallWndProcHook);
-      tls_data->hCallWndProcHook = NULL;
-   }
-}
diff --git a/src/gallium/state_trackers/wgl/shared/stw_framebuffer.h b/src/gallium/state_trackers/wgl/shared/stw_framebuffer.h
index e7fa51c3a81..d6f5950ac3e 100644
--- a/src/gallium/state_trackers/wgl/shared/stw_framebuffer.h
+++ b/src/gallium/state_trackers/wgl/shared/stw_framebuffer.h
@@ -79,10 +79,4 @@ struct stw_framebuffer *
 stw_framebuffer_from_hdc(
    HDC hdc );
 
-boolean
-stw_framebuffer_init_thread(void);
-
-void
-stw_framebuffer_cleanup_thread(void);
-
 #endif /* STW_FRAMEBUFFER_H */
diff --git a/src/gallium/state_trackers/wgl/shared/stw_tls.c b/src/gallium/state_trackers/wgl/shared/stw_tls.c
index 0c18a52352c..4bd6a9289c9 100644
--- a/src/gallium/state_trackers/wgl/shared/stw_tls.c
+++ b/src/gallium/state_trackers/wgl/shared/stw_tls.c
@@ -51,9 +51,23 @@ stw_tls_data_create()
 
    data = CALLOC_STRUCT(stw_tls_data);
    if (!data)
-      return NULL;
+      goto no_data;
+
+   data->hCallWndProcHook = SetWindowsHookEx(WH_CALLWNDPROC,
+                                             stw_call_window_proc,
+                                             NULL,
+                                             GetCurrentThreadId());
+   if(data->hCallWndProcHook == NULL)
+      goto no_hook;
+
+   TlsSetValue(tlsIndex, data);
 
    return data;
+
+no_hook:
+   FREE(data);
+no_data:
+   return NULL;
 }
 
 boolean
@@ -69,8 +83,6 @@ stw_tls_init_thread(void)
    if(!data)
       return FALSE;
 
-   TlsSetValue(tlsIndex, data);
-
    return TRUE;
 }
 
@@ -84,8 +96,16 @@ stw_tls_cleanup_thread(void)
    }
 
    data = (struct stw_tls_data *) TlsGetValue(tlsIndex);
-   TlsSetValue(tlsIndex, NULL);
-   FREE(data);
+   if(data) {
+      TlsSetValue(tlsIndex, NULL);
+   
+      if(data->hCallWndProcHook) {
+         UnhookWindowsHookEx(data->hCallWndProcHook);
+         data->hCallWndProcHook = NULL;
+      }
+   
+      FREE(data);
+   }
 }
 
 void
@@ -110,12 +130,9 @@ stw_tls_get_data(void)
    if(!data) {
       /* DllMain is called with DLL_THREAD_ATTACH only by threads created after 
        * the DLL is loaded by the process */
-      
       data = stw_tls_data_create();
       if(!data)
          return NULL;
-
-      TlsSetValue(tlsIndex, data);
    }
 
    return data;
diff --git a/src/gallium/state_trackers/wgl/shared/stw_tls.h b/src/gallium/state_trackers/wgl/shared/stw_tls.h
index 6af8be70c9f..fbf8b1cbee4 100644
--- a/src/gallium/state_trackers/wgl/shared/stw_tls.h
+++ b/src/gallium/state_trackers/wgl/shared/stw_tls.h
@@ -50,4 +50,10 @@ stw_tls_cleanup(void);
 struct stw_tls_data *
 stw_tls_get_data(void);
 
+LRESULT CALLBACK
+stw_call_window_proc(
+   int nCode,
+   WPARAM wParam,
+   LPARAM lParam );
+
 #endif /* STW_TLS_H */
-- 
cgit v1.2.3


From 42882897c67f6c74e67e120e946a95929e6c2065 Mon Sep 17 00:00:00 2001
From: José Fonseca <jfonseca@vmware.com>
Date: Wed, 17 Jun 2009 21:28:18 +0100
Subject: wgl: Fix window resizing in multithread applications.

In multithreading stw_call_window_proc can be called by a thread other
than the thread where the context is bound.
---
 .../state_trackers/wgl/shared/stw_context.c        |  25 ++++-
 src/gallium/state_trackers/wgl/shared/stw_device.c |  24 +++++
 .../state_trackers/wgl/shared/stw_framebuffer.c    | 103 ++++++++++++---------
 .../state_trackers/wgl/shared/stw_framebuffer.h    |   7 +-
 4 files changed, 112 insertions(+), 47 deletions(-)

(limited to 'src/gallium/state_trackers/wgl/shared')

diff --git a/src/gallium/state_trackers/wgl/shared/stw_context.c b/src/gallium/state_trackers/wgl/shared/stw_context.c
index 1c217699ab1..9df1ab76526 100644
--- a/src/gallium/state_trackers/wgl/shared/stw_context.c
+++ b/src/gallium/state_trackers/wgl/shared/stw_context.c
@@ -116,6 +116,18 @@ stw_share_lists(
    return ret;
 }
 
+static void
+stw_viewport(GLcontext * glctx, GLint x, GLint y,
+             GLsizei width, GLsizei height)
+{
+   struct stw_context *ctx = (struct stw_context *)glctx->DriverCtx;
+   struct stw_framebuffer *fb;
+   
+   fb = stw_framebuffer_from_hdc( ctx->hdc );
+   if(fb)
+      stw_framebuffer_update(fb);
+}
+
 UINT_PTR
 stw_create_layer_context(
    HDC hdc,
@@ -175,6 +187,7 @@ stw_create_layer_context(
       goto no_st_ctx;
 
    ctx->st->ctx->DriverCtx = ctx;
+   ctx->st->ctx->Driver.Viewport = stw_viewport;
 
    pipe_mutex_lock( stw_dev->mutex );
    ctx->hglrc = handle_table_add(stw_dev->ctx_table, ctx);
@@ -298,8 +311,11 @@ stw_make_current(
 	 st_flush(curctx->st, PIPE_FLUSH_RENDER_CACHE, NULL);
       
       /* Return if already current. */
-      if (curctx->hglrc == hglrc && curctx->hdc == hdc)
-         return TRUE;
+      if (curctx->hglrc == hglrc && curctx->hdc == hdc) {
+         ctx = curctx;
+         fb = stw_framebuffer_from_hdc( hdc );
+         goto success;
+      }
    }
 
    if (hdc == NULL || hglrc == 0) {
@@ -343,7 +359,10 @@ stw_make_current(
    if(!st_make_current( ctx->st, fb->stfb, fb->stfb ))
       goto fail;
 
-   stw_framebuffer_resize(fb);
+success:
+   assert(fb);
+   if(fb)
+      stw_framebuffer_update(fb);
    
    return TRUE;
 
diff --git a/src/gallium/state_trackers/wgl/shared/stw_device.c b/src/gallium/state_trackers/wgl/shared/stw_device.c
index 070ffcb3ca1..1b4a2d5cdbd 100644
--- a/src/gallium/state_trackers/wgl/shared/stw_device.c
+++ b/src/gallium/state_trackers/wgl/shared/stw_device.c
@@ -30,6 +30,7 @@
 #include "glapi/glthread.h"
 #include "util/u_debug.h"
 #include "pipe/p_screen.h"
+#include "state_tracker/st_public.h"
 
 #ifdef DEBUG
 #include "trace/tr_screen.h"
@@ -63,7 +64,26 @@ stw_flush_frontbuffer(struct pipe_screen *screen,
 {
    const struct stw_winsys *stw_winsys = stw_dev->stw_winsys;
    HDC hdc = (HDC)context_private;
+   struct stw_framebuffer *fb;
    
+   fb = stw_framebuffer_from_hdc( hdc );
+   assert(fb);
+   if (fb == NULL)
+      return;
+
+   pipe_mutex_lock( fb->mutex );
+
+#if DEBUG
+   {
+      struct pipe_surface *surface2;
+
+      if(!st_get_framebuffer_surface( fb->stfb, ST_SURFACE_FRONT_LEFT, &surface2 ))
+         assert(0);
+      else
+         assert(surface2 == surface);
+   }
+#endif
+
 #ifdef DEBUG
    if(stw_dev->trace_running) {
       screen = trace_screen(screen)->screen;
@@ -72,6 +92,10 @@ stw_flush_frontbuffer(struct pipe_screen *screen,
 #endif
    
    stw_winsys->flush_frontbuffer(screen, surface, hdc);
+   
+   stw_framebuffer_update(fb);
+   
+   pipe_mutex_unlock( fb->mutex );
 }
 
 
diff --git a/src/gallium/state_trackers/wgl/shared/stw_framebuffer.c b/src/gallium/state_trackers/wgl/shared/stw_framebuffer.c
index 88043859ce4..7d0e8f46482 100644
--- a/src/gallium/state_trackers/wgl/shared/stw_framebuffer.c
+++ b/src/gallium/state_trackers/wgl/shared/stw_framebuffer.c
@@ -111,15 +111,10 @@ stw_call_window_proc(
          unsigned width = LOWORD( pParams->lParam );
          unsigned height = HIWORD( pParams->lParam );
          
-         /* FIXME: The mesa statetracker makes the assumptions that only
-          * one context is using the framebuffer, and that that context is the 
-          * current one. However neither holds true, as WGL allows more than
-          * one context to be bound to the same drawable, and this function can 
-          * be called from any thread.
-          */
          pipe_mutex_lock( fb->mutex );
-         if (fb->stfb)
-            st_resize_framebuffer( fb->stfb, width, height );
+         fb->must_resize = TRUE;
+         fb->width = width;
+         fb->height = height;
          pipe_mutex_unlock( fb->mutex );
       }
    }
@@ -140,6 +135,31 @@ stw_call_window_proc(
 }
 
 
+static void
+stw_framebuffer_get_size( struct stw_framebuffer *fb )
+{
+   unsigned width, height;
+   RECT rect;
+
+   assert(fb->hWnd);
+   
+   GetClientRect( fb->hWnd, &rect );
+   width = rect.right - rect.left;
+   height = rect.bottom - rect.top;
+
+   if(width < 1)
+      width = 1;
+   if(height < 1)
+      height = 1;
+
+   if(width != fb->width || height != fb->height) {
+      fb->must_resize = TRUE;
+      fb->width = width; 
+      fb->height = height; 
+   }
+}
+
+
 /**
  * Create a new framebuffer object which will correspond to the given HDC.
  */
@@ -169,6 +189,8 @@ stw_framebuffer_create_locked(
 
    stw_pixelformat_visual(&fb->visual, pfi);
    
+   stw_framebuffer_get_size(fb);
+
    pipe_mutex_init( fb->mutex );
 
    fb->next = stw_dev->fb_head;
@@ -178,32 +200,6 @@ stw_framebuffer_create_locked(
 }
 
 
-static void
-stw_framebuffer_get_size( struct stw_framebuffer *fb, GLuint *pwidth, GLuint *pheight )
-{
-   GLuint width, height;
-
-   if (fb->hWnd) {
-      RECT rect;
-      GetClientRect( fb->hWnd, &rect );
-      width = rect.right - rect.left;
-      height = rect.bottom - rect.top;
-   }
-   else {
-      width = GetDeviceCaps( fb->hDC, HORZRES );
-      height = GetDeviceCaps( fb->hDC, VERTRES );
-   }
-
-   if(width < 1)
-      width = 1;
-   if(height < 1)
-      height = 1;
-
-   *pwidth = width; 
-   *pheight = height; 
-}
-
-
 BOOL
 stw_framebuffer_allocate(
    struct stw_framebuffer *fb)
@@ -213,7 +209,6 @@ stw_framebuffer_allocate(
    if(!fb->stfb) {
       const struct stw_pixelformat_info *pfi = fb->pfi;
       enum pipe_format colorFormat, depthFormat, stencilFormat;
-      GLuint width, height; 
 
       colorFormat = pfi->color_format;
       
@@ -229,16 +224,21 @@ stw_framebuffer_allocate(
       else
          stencilFormat = PIPE_FORMAT_NONE;
    
-      stw_framebuffer_get_size(fb, &width, &height);
-      
+      assert(fb->must_resize);
+      assert(fb->width);
+      assert(fb->height);
+
       fb->stfb = st_create_framebuffer(
          &fb->visual,
          colorFormat,
          depthFormat,
          stencilFormat,
-         width,
-         height,
+         fb->width,
+         fb->height,
          (void *) fb );
+      
+      // to notify the context
+      fb->must_resize = TRUE;
    }
    
    pipe_mutex_unlock( fb->mutex );
@@ -247,14 +247,29 @@ stw_framebuffer_allocate(
 }
 
 
+/**
+ * Update the framebuffer's size if necessary.
+ */
 void
-stw_framebuffer_resize(
+stw_framebuffer_update(
    struct stw_framebuffer *fb)
 {
-   GLuint width, height; 
    assert(fb->stfb);
-   stw_framebuffer_get_size(fb, &width, &height);
-   st_resize_framebuffer(fb->stfb, width, height);
+   assert(fb->height);
+   assert(fb->width);
+   
+   /* XXX: It would be nice to avoid checking the size again -- in theory  
+    * stw_call_window_proc would have cought the resize and stored the right 
+    * size already, but unfortunately threads created before the DllMain is 
+    * called don't get a DLL_THREAD_ATTACH notification, and there is no way
+    * to know of their existing without using the not very portable PSAPI.
+    */
+   stw_framebuffer_get_size(fb);
+   
+   if(fb->must_resize) {
+      st_resize_framebuffer(fb->stfb, fb->width, fb->height);
+      fb->must_resize = FALSE;
+   }
 }                      
 
 
@@ -407,6 +422,8 @@ stw_swap_buffers(
 
    stw_dev->stw_winsys->flush_frontbuffer( screen, surface, hdc );
    
+   stw_framebuffer_update(fb);
+   
    pipe_mutex_unlock( fb->mutex );
    
    return TRUE;
diff --git a/src/gallium/state_trackers/wgl/shared/stw_framebuffer.h b/src/gallium/state_trackers/wgl/shared/stw_framebuffer.h
index d6f5950ac3e..759e06b8914 100644
--- a/src/gallium/state_trackers/wgl/shared/stw_framebuffer.h
+++ b/src/gallium/state_trackers/wgl/shared/stw_framebuffer.h
@@ -51,6 +51,11 @@ struct stw_framebuffer
    pipe_mutex mutex;
    struct st_framebuffer *stfb;
    
+   /* FIXME: Make this work for multiple contexts bound to the same framebuffer */
+   boolean must_resize;
+   unsigned width;
+   unsigned height;
+   
    /** This is protected by stw_device::mutex, not the mutex above */
    struct stw_framebuffer *next;
 };
@@ -65,7 +70,7 @@ stw_framebuffer_allocate(
    struct stw_framebuffer *fb );
 
 void
-stw_framebuffer_resize(
+stw_framebuffer_update(
    struct stw_framebuffer *fb);
 
 void
-- 
cgit v1.2.3


From c25534f30d326c15dff845775d9bd55ba6064049 Mon Sep 17 00:00:00 2001
From: José Fonseca <jfonseca@vmware.com>
Date: Wed, 24 Jun 2009 14:46:07 +0100
Subject: wgl: Handle flush after a window is destroyed.

Fixes assertion failure with conform.
---
 src/gallium/state_trackers/wgl/shared/stw_device.c | 41 +++++++++++-----------
 1 file changed, 21 insertions(+), 20 deletions(-)

(limited to 'src/gallium/state_trackers/wgl/shared')

diff --git a/src/gallium/state_trackers/wgl/shared/stw_device.c b/src/gallium/state_trackers/wgl/shared/stw_device.c
index 1b4a2d5cdbd..ce466241463 100644
--- a/src/gallium/state_trackers/wgl/shared/stw_device.c
+++ b/src/gallium/state_trackers/wgl/shared/stw_device.c
@@ -67,35 +67,36 @@ stw_flush_frontbuffer(struct pipe_screen *screen,
    struct stw_framebuffer *fb;
    
    fb = stw_framebuffer_from_hdc( hdc );
-   assert(fb);
-   if (fb == NULL)
-      return;
-
-   pipe_mutex_lock( fb->mutex );
+   /* fb can be NULL if window was destroyed already */
+   if (fb) {
+      pipe_mutex_lock( fb->mutex );
 
 #if DEBUG
-   {
-      struct pipe_surface *surface2;
-
-      if(!st_get_framebuffer_surface( fb->stfb, ST_SURFACE_FRONT_LEFT, &surface2 ))
-         assert(0);
-      else
-         assert(surface2 == surface);
-   }
+      {
+         struct pipe_surface *surface2;
+   
+         if(!st_get_framebuffer_surface( fb->stfb, ST_SURFACE_FRONT_LEFT, &surface2 ))
+            assert(0);
+         else
+            assert(surface2 == surface);
+      }
 #endif
 
 #ifdef DEBUG
-   if(stw_dev->trace_running) {
-      screen = trace_screen(screen)->screen;
-      surface = trace_surface(surface)->surface;
-   }
+      if(stw_dev->trace_running) {
+         screen = trace_screen(screen)->screen;
+         surface = trace_surface(surface)->surface;
+      }
 #endif
+   }
    
    stw_winsys->flush_frontbuffer(screen, surface, hdc);
    
-   stw_framebuffer_update(fb);
-   
-   pipe_mutex_unlock( fb->mutex );
+   if(fb) {
+      stw_framebuffer_update(fb);
+      
+      pipe_mutex_unlock( fb->mutex );
+   }
 }
 
 
-- 
cgit v1.2.3