Mesa (master): st/mesa: fix sampler_view destruction bug when texture is shared

[Brian Paul]

Module: Mesa
Branch: master
Commit: 2d6befd9d1e8dcf6495fe1b9cef12224046f3095
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=2d6befd9d1e8dcf6495fe1b9cef12224046f3095

Author: Brian Paul <brianp at vmware.com>
Date:   Wed Mar 24 08:34:26 2010 -0600

st/mesa: fix sampler_view destruction bug when texture is shared

Since texture's can be shared by many contexts, the texture's sampler
view's context pointer might be invalid by time we delete the texture.

Prevent crashes/etc by setting the sampler view's context to be the
calling context before deleting it.  This should be safe as long as
all contexts which share the texture are using the same gallium driver.
That's a reasonable assumption since pipe_texture objects aren't
compatible between different drivers anyway.

---

 src/mesa/state_tracker/st_cb_texture.c |   12 ++++++++++--
 1 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/src/mesa/state_tracker/st_cb_texture.c b/src/mesa/state_tracker/st_cb_texture.c
index d7a774a..bda17cd 100644
--- a/src/mesa/state_tracker/st_cb_texture.c
+++ b/src/mesa/state_tracker/st_cb_texture.c
@@ -124,9 +124,17 @@ st_DeleteTextureObject(GLcontext *ctx,
    struct st_texture_object *stObj = st_texture_object(texObj);
    if (stObj->pt)
       pipe_texture_reference(&stObj->pt, NULL);
-   if (stObj->sampler_view)
+   if (stObj->sampler_view) {
+      if (stObj->sampler_view->context != ctx->st->pipe) {
+         /* Take "ownership" of this texture sampler view by setting
+          * its context pointer to this context.  This avoids potential
+          * crashes when the texture object is shared among contexts
+          * and the original/owner context has already been destroyed.
+          */
+         stObj->sampler_view->context == ctx->st->pipe;
+      }
       pipe_sampler_view_reference(&stObj->sampler_view, NULL);
-
+   }
    _mesa_delete_texture_object(ctx, texObj);
 }