[Mesa-dev] [PATCH] st/mesa: fix texture deletion context mix-up issues

[Neha Bhende]

Thanks for the fix!

Reviewed-by: Neha Bhende <bhenden at vmware.com>

Regards,
Neha

________________________________________
From: Brian Paul <brianp at vmware.com>
Sent: Thursday, March 21, 2019 6:19 PM
To: mesa-dev at lists.freedesktop.org
Cc: Neha Bhende
Subject: [PATCH] st/mesa: fix texture deletion context mix-up issues

When we destroy a context, we need to temporarily make that context
the current one for the thread.

That's because during context tear-down we make many calls to
_mesa_reference_texobj(&texObj, NULL).  Note there's no context
parameter.  If the texture's refcount goes to zero and we need to
delete it, we use the thread's current context.  But if that context
isn't the context we're tearing down, we get into trouble when
deallocating sampler views.  See patch 593e36f956 ("st/mesa:
implement "zombie" sampler views (v2)") for background information.

Also, we need to release any sampler views attached to the fallback
textures.

Fixes a crash on exit with a glretrace of the Nobel Clinician
application.
---
 src/mesa/state_tracker/st_context.c | 46 +++++++++++++++++++++++++++----------
 1 file changed, 34 insertions(+), 12 deletions(-)

diff --git a/src/mesa/state_tracker/st_context.c b/src/mesa/state_tracker/st_context.c
index f037384..9b23d75 100644
--- a/src/mesa/state_tracker/st_context.c
+++ b/src/mesa/state_tracker/st_context.c
@@ -917,15 +917,39 @@ st_destroy_context(struct st_context *st)
 {
    struct gl_context *ctx = st->ctx;
    struct st_framebuffer *stfb, *next;
+   struct gl_framebuffer *save_drawbuffer;
+   struct gl_framebuffer *save_readbuffer;
+
+   /* Save the current context and draw/read buffers*/
+   GET_CURRENT_CONTEXT(save_ctx);
+   if (save_ctx) {
+      save_drawbuffer = save_ctx->WinSysDrawBuffer;
+      save_readbuffer = save_ctx->WinSysReadBuffer;
+   } else {
+      save_drawbuffer = save_readbuffer = NULL;
+   }

-   GET_CURRENT_CONTEXT(curctx);
+   /*
+    * We need to bind the context we're deleting so that
+    * _mesa_reference_texobj_() uses this context when deleting textures.
+    * Similarly for framebuffer objects, etc.
+    */
+   _mesa_make_current(ctx, NULL, NULL);

-   if (curctx == NULL) {
-      /* No current context, but we need one to release
-       * renderbuffer surface when we release framebuffer.
-       * So temporarily bind the context.
-       */
-      _mesa_make_current(ctx, NULL, NULL);
+   /* This must be called first so that glthread has a chance to finish */
+   _mesa_glthread_destroy(ctx);
+
+   _mesa_HashWalk(ctx->Shared->TexObjects, destroy_tex_sampler_cb, st);
+
+   /* For the fallback textures, free any sampler views belonging to this
+    * context.
+    */
+   for (unsigned i = 0; i < NUM_TEXTURE_TARGETS; i++) {
+      struct st_texture_object *stObj =
+         st_texture_object(ctx->Shared->FallbackTex[i]);
+      if (stObj) {
+         st_texture_release_context_sampler_view(st, stObj);
+      }
    }

    st_context_free_zombie_objects(st);
@@ -933,11 +957,6 @@ st_destroy_context(struct st_context *st)
    mtx_destroy(&st->zombie_sampler_views.mutex);
    mtx_destroy(&st->zombie_shaders.mutex);

-   /* This must be called first so that glthread has a chance to finish */
-   _mesa_glthread_destroy(ctx);
-
-   _mesa_HashWalk(ctx->Shared->TexObjects, destroy_tex_sampler_cb, st);
-
    st_reference_fragprog(st, &st->fp, NULL);
    st_reference_prog(st, &st->gp, NULL);
    st_reference_vertprog(st, &st->vp, NULL);
@@ -965,4 +984,7 @@ st_destroy_context(struct st_context *st)
    st = NULL;

    free(ctx);
+
+   /* Restore the current context and draw/read buffers */
+   _mesa_make_current(save_ctx, save_drawbuffer, save_readbuffer);
 }
--
1.8.5.6