mesa/glthread: restore the dispatch table when incompatible gl calls are detected

While a context only has a single glthread, the context itself can be
attached to several threads. Therefore the dispatch table must be
updated in all threads before the destruction of glthread. In others
words, glthread can only be destroyed safely when the context is deleted.

Fixes remaining crashes in the glx-multithread-makecurrent* tests.

V2: (Timothy Arceri) updated gl_API.dtd marshal_fail description.

Signed-off-by: Gregory Hainaut <gregory.hainaut@gmail.com>
Acked-by: Timothy Arceri <tarceri@itsqueeze.com>
Acked-by: Marek Olšák <maraeo@gmail.com>
Tested-by: Dieter Nützel <Dieter@nuetzel-hh.de>
Tested-by: Mike Lothian <mike@fireburn.co.uk>

src/mapi/glapi/gen/gl_API.dtd

@@ -131,9 +131,9 @@ param:
         If "draw", it will follow the "async" rules except that "indices" are
         ignored (since they may come from a VBO).
      marshal_fail - an expression that, if it evaluates true, causes glthread
-        to finish and tear down before the Mesa implementation is called
-        directly.  Used to disable glthread for GL compatibility interactions
-        that we don't want to track state for.
+        to switch back to the Mesa implementation and call it directly.  Used
+        to disable glthread for GL compatibility interactions that we don't
+        want to track state for.
 
 glx:
      rop - Opcode value for "render" commands

src/mapi/glapi/gen/gl_marshal.py

@@ -239,7 +239,8 @@ class PrintCode(gl_XML.gl_print_base):
             if func.marshal_fail:
                 out('if ({0}) {{'.format(func.marshal_fail))
                 with indent():
-                    out('_mesa_glthread_destroy(ctx);')
+                    out('_mesa_glthread_finish(ctx);')
+                    out('_mesa_glthread_restore_dispatch(ctx);')
                     self.print_sync_dispatch(func)
                     out('return;')
                 out('}')

src/mesa/main/glthread.c

@@ -173,6 +173,12 @@ _mesa_glthread_destroy(struct gl_context *ctx)
    free(glthread);
    ctx->GLThread = NULL;
 
+   _mesa_glthread_restore_dispatch(ctx);
+}
+
+void
+_mesa_glthread_restore_dispatch(struct gl_context *ctx)
+{
    /* Remove ourselves from the dispatch table except if another ctx/thread
     * already installed a new dispatch table.
     *

src/mesa/main/glthread.h

@@ -119,6 +119,7 @@ struct glthread_batch
 void _mesa_glthread_init(struct gl_context *ctx);
 void _mesa_glthread_destroy(struct gl_context *ctx);
 
+void _mesa_glthread_restore_dispatch(struct gl_context *ctx);
 void _mesa_glthread_flush_batch(struct gl_context *ctx);
 void _mesa_glthread_finish(struct gl_context *ctx);
 
@@ -138,5 +139,11 @@ static inline void
 _mesa_glthread_finish(struct gl_context *ctx)
 {
 }
+
+static inline void
+_mesa_glthread_restore_dispatch(struct gl_context *ctx);
+{
+}
+
 #endif /* !HAVE_PTHREAD */
 #endif /* _GLTHREAD_H*/