[PATCH] DRI2: handle drawable destruction properly at DRI2SwapComplete time

[Jesse Barnes]

Simon reported an issue with kwin that turned out to be a general problem.  If
a drawable goes away before its swap completes, we'll try to free it up.
However, we free it improperly, which causes a server crash in
DRI2DestroyDrawable.  Fix that up by splitting the free code out and calling
it from DRI2SwapComplete.

Tested-by: Simon Thum <simon.thum at gmx.de>
Signed-off-by: Jesse Barnes <jbarnes at virtuousgeek.org>

diff --git a/hw/xfree86/dri2/dri2.c b/hw/xfree86/dri2/dri2.c
index 3db826e..97c79d6 100644
--- a/hw/xfree86/dri2/dri2.c
+++ b/hw/xfree86/dri2/dri2.c
@@ -157,6 +157,31 @@ DRI2CreateDrawable(DrawablePtr pDraw)
     return Success;
 }
 
+static void
+DRI2FreeDrawable(DrawablePtr pDraw)
+{
+    DRI2DrawablePtr pPriv;
+    WindowPtr  	    pWin;
+    PixmapPtr	    pPixmap;
+
+    pPriv = DRI2GetDrawable(pDraw);
+    if (pPriv == NULL)
+	return;
+
+    xfree(pPriv);
+
+    if (pDraw->type == DRAWABLE_WINDOW)
+    {
+	pWin = (WindowPtr) pDraw;
+	dixSetPrivate(&pWin->devPrivates, dri2WindowPrivateKey, NULL);
+    }
+    else
+    {
+	pPixmap = (PixmapPtr) pDraw;
+	dixSetPrivate(&pPixmap->devPrivates, dri2PixmapPrivateKey, NULL);
+    }
+}
+
 static int
 find_attachment(DRI2DrawablePtr pPriv, unsigned attachment)
 {
@@ -507,7 +532,7 @@ DRI2SwapComplete(ClientPtr client, DrawablePtr pDraw, int frame,
     if (pPriv->refCount == 0) {
         xf86DrvMsg(pScreen->myNum, X_ERROR,
 		   "[DRI2] %s: bad drawable refcount\n", __func__);
-	xfree(pPriv);
+	DRI2FreeDrawable(pDraw);
 	return;
     }
 
@@ -728,8 +753,6 @@ DRI2DestroyDrawable(DrawablePtr pDraw)
 {
     DRI2ScreenPtr   ds = DRI2GetScreen(pDraw->pScreen);
     DRI2DrawablePtr pPriv;
-    WindowPtr  	    pWin;
-    PixmapPtr	    pPixmap;
 
     pPriv = DRI2GetDrawable(pDraw);
     if (pPriv == NULL)
@@ -752,18 +775,7 @@ DRI2DestroyDrawable(DrawablePtr pDraw)
      * actually free the priv yet.  We'll need it in the DRI2SwapComplete()
      * callback and we'll free it there once we're done. */
     if (!pPriv->swapsPending)
-	xfree(pPriv);
-
-    if (pDraw->type == DRAWABLE_WINDOW)
-    {
-	pWin = (WindowPtr) pDraw;
-	dixSetPrivate(&pWin->devPrivates, dri2WindowPrivateKey, NULL);
-    }
-    else
-    {
-	pPixmap = (PixmapPtr) pDraw;
-	dixSetPrivate(&pPixmap->devPrivates, dri2PixmapPrivateKey, NULL);
-    }
+	DRI2FreeDrawable(pDraw);
 }
 
 Bool