From b47d231526821f5cff99546a984103a7222bc66c Mon Sep 17 00:00:00 2001 From: Daniel Kurtz Date: Fri, 7 Feb 2014 19:29:06 +0800 Subject: [PATCH] glsl: Add locking to builtin_builder singleton Consider a multithreaded program with two contexts A and B, and the following scenario: 1. Context A calls initialize(), which allocates mem_ctx and starts building built-ins. 2. Context B calls initialize(), which sees mem_ctx != NULL and assumes everything is already set up. It returns. 3. Context B calls find(), which fails to find the built-in since it hasn't been created yet. 4. Context A finally finishes initializing the built-ins. This will break at step 3. Adding a lock ensures that subsequent callers of initialize() will wait until initialization is actually complete. Similarly, if any thread calls release while another thread is still initializing, or calling find(), the mem_ctx/shader would get free'd while from under it, leading to corruption or use-after-free crashes. Fixes sporadic failures in Piglit's glx-multithread-shader-compile. Bugzilla: https://bugs.freedesktop.org/69200 Signed-off-by: Daniel Kurtz Signed-off-by: Kenneth Graunke Reviewed-by: Kenneth Graunke Cc: "10.1 10.0" --- src/glsl/builtin_functions.cpp | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) diff --git a/src/glsl/builtin_functions.cpp b/src/glsl/builtin_functions.cpp index aeb8e5d9461..2162baa27e5 100644 --- a/src/glsl/builtin_functions.cpp +++ b/src/glsl/builtin_functions.cpp @@ -4100,6 +4100,7 @@ builtin_builder::_mid3(const glsl_type *type) /* The singleton instance of builtin_builder. */ static builtin_builder builtins; +_glthread_DECLARE_STATIC_MUTEX(builtins_lock); /** * External API (exposing the built-in module to the rest of the compiler): @@ -4108,20 +4109,28 @@ static builtin_builder builtins; void _mesa_glsl_initialize_builtin_functions() { + _glthread_LOCK_MUTEX(builtins_lock); builtins.initialize(); + _glthread_UNLOCK_MUTEX(builtins_lock); } void _mesa_glsl_release_builtin_functions() { + _glthread_LOCK_MUTEX(builtins_lock); builtins.release(); + _glthread_UNLOCK_MUTEX(builtins_lock); } ir_function_signature * _mesa_glsl_find_builtin_function(_mesa_glsl_parse_state *state, const char *name, exec_list *actual_parameters) { - return builtins.find(state, name, actual_parameters); + ir_function_signature * s; + _glthread_LOCK_MUTEX(builtins_lock); + s = builtins.find(state, name, actual_parameters); + _glthread_UNLOCK_MUTEX(builtins_lock); + return s; } gl_shader * -- 2.30.2