From 5e8967b338736ead2c7d856a709a219fd6d37d92 Mon Sep 17 00:00:00 2001 From: Daniel Kurtz Date: Thu, 6 Feb 2014 19:05:35 +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. Signed-off-by: Kenneth Graunke Signed-off-by: Daniel Kurtz --- 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 840a6c9..c64fa3b 100644 --- a/src/glsl/builtin_functions.cpp +++ b/src/glsl/builtin_functions.cpp @@ -3997,6 +3997,7 @@ builtin_builder::_atomic_op(const char *intrinsic, /* 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): @@ -4005,20 +4006,28 @@ 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 * -- 1.9.0.rc1.175.g0b1dcb5