Data race in pthread_barrier_wait detected by ThreadSanitizer upon closing the Editor

[Rubonnek]

Tested versions

63d6bda - reproducible

System information

Godot v4.3.dev (63d6bda) - Arch Linux #1 SMP PREEMPT_DYNAMIC Fri, 02 Feb 2024 17:03:55 +0000 - Tty - Vulkan (Forward+) - dedicated AMD Radeon RX 6900 XT (RADV NAVI21) () - AMD Ryzen 9 5950X 16-Core Processor (32 Threads)

Issue description

Closing the Editor against an empty project with ThreadSanitizer enabled will generate a data race warning in pthread_barrier_wait.

Steps to reproduce

1. Compile Godot with ThreadSanitizer enabled -- the following is the command I used:

scons -Q -s platform=linuxbsd dev_mode=yes dev_build=yes udev=yes target=editor debug_symbols=yes precision=single bits=64 optimize=debug compiledb=yes use_llvm=yes linker=lld tests=yes use_asan=no use_tsan=yes werror=no -j$(nproc)

If you are on Arch Linux, it seems that linking to libatomic.a is unnecessary -- you may need to apply the following patch and try to compile again if it previously failed:

diff --git a/platform/linuxbsd/detect.py b/platform/linuxbsd/detect.py
index 7946ef6228..14471c2393 100644
--- a/platform/linuxbsd/detect.py
+++ b/platform/linuxbsd/detect.py
@@ -520,8 +520,6 @@ def configure(env: "Environment"):
     # Link those statically for portability
     if env["use_static_cpp"]:
         env.Append(LINKFLAGS=["-static-libgcc", "-static-libstdc++"])
-        if env["use_llvm"] and platform.system() != "FreeBSD":
-            env["LINKCOM"] = env["LINKCOM"] + " -l:libatomic.a"
     else:
         if env["use_llvm"] and platform.system() != "FreeBSD":
             env.Append(LIBS=["atomic"])

2. Decompress the MRP below and open a terminal at the MRP project path and run:

TSAN_OPTIONS=second_deadlock_stack=1 /opt/godot/bin/godot.linuxbsd.editor.dev.x86_64.llvm.san -e

If the FATAL: ThreadSanitizer: unexpected memory mapping error appears, you may need to temporarily lower the ASLR entropy:

sudo sysctl vm.mmap_rnd_bits=28
# reverse it with: sudo sysctl vm.mmap_rnd_bits=32

OR disable ASLR entirely temporarily :

sudo sysctl kernel.randomize_va_space=0
# reverse it with: sudo sysctl kernel.randomize_va_space=2

3. The following ThreadSanitizer warning should appear after closing the Editor:

==================
WARNING: ThreadSanitizer: data race (pid=41490)
  Read of size 1 at 0x7ffef9873f40 by thread T36:
    #0 pthread_barrier_wait <null> (godot.linuxbsd.editor.dev.x86_64.llvm.san+0x3b42151) (BuildId: 77398a27c54674f8)
    #1 <null> <null> (libvulkan_radeon.so+0x23102d) (BuildId: 0162f9f3c2516d03ae83012d794ea26051a87d33)

  Previous write of size 1 at 0x7ffef9873f40 by thread T40:
    #0 pthread_barrier_destroy <null> (godot.linuxbsd.editor.dev.x86_64.llvm.san+0x3b2499f) (BuildId: 77398a27c54674f8)
    #1 <null> <null> (libvulkan_radeon.so+0x237dac) (BuildId: 0162f9f3c2516d03ae83012d794ea26051a87d33)

  Location is stack of main thread.

  Location is global '??' at 0x7ffef9855000 ([stack]+0x1ef40)

  Thread T36 'godot.l:disk$0' (tid=41530, running) created by main thread at:
    #0 pthread_create <null> (godot.linuxbsd.editor.dev.x86_64.llvm.san+0x3b0da76) (BuildId: 77398a27c54674f8)
    #1 <null> <null> (libvulkan_radeon.so+0x44897d) (BuildId: 0162f9f3c2516d03ae83012d794ea26051a87d33)
    #2 VulkanContext::_window_create(int, DisplayServer::VSyncMode, VkSurfaceKHR_T*, int, int) /opt/godot/drivers/vulkan/vulkan_context.cpp:1853:15 (godot.linuxbsd.editor.dev.x86_64.llvm.san+0x567ec18) (BuildId: 77398a27c54674f8)
    #3 VulkanContextX11::window_create(int, DisplayServer::VSyncMode, int, int, void const*) /opt/godot/platform/linuxbsd/x11/vulkan_context_x11.cpp:56:9 (godot.linuxbsd.editor.dev.x86_64.llvm.san+0x3c4262d) (BuildId: 77398a27c54674f8)
    #4 DisplayServerX11::_create_window(DisplayServer::WindowMode, DisplayServer::VSyncMode, unsigned int, Rect2i const&) /opt/godot/platform/linuxbsd/x11/display_server_x11.cpp:5674:28 (godot.linuxbsd.editor.dev.x86_64.llvm.san+0x3bc9c91) (BuildId: 77398a27c54674f8)
    #5 DisplayServerX11::DisplayServerX11(String const&, DisplayServer::WindowMode, DisplayServer::VSyncMode, unsigned int, Vector2i const*, Vector2i const&, int, Error&) /opt/godot/platform/linuxbsd/x11/display_server_x11.cpp:6183:25 (godot.linuxbsd.editor.dev.x86_64.llvm.san+0x3be8705) (BuildId: 77398a27c54674f8)
    #6 DisplayServerX11::create_func(String const&, DisplayServer::WindowMode, DisplayServer::VSyncMode, unsigned int, Vector2i const*, Vector2i const&, int, Error&) /opt/godot/platform/linuxbsd/x11/display_server_x11.cpp:5348:22 (godot.linuxbsd.editor.dev.x86_64.llvm.san+0x3be5804) (BuildId: 77398a27c54674f8)
    #7 DisplayServer::create(int, String const&, DisplayServer::WindowMode, DisplayServer::VSyncMode, unsigned int, Vector2i const*, Vector2i const&, int, Error&) /opt/godot/servers/display_server.cpp:978:9 (godot.linuxbsd.editor.dev.x86_64.llvm.san+0x87e6993) (BuildId: 77398a27c54674f8)
    #8 Main::setup2() /opt/godot/main/main.cpp:2600:20 (godot.linuxbsd.editor.dev.x86_64.llvm.san+0x3cc0d4b) (BuildId: 77398a27c54674f8)
    #9 Main::setup(char const*, int, char**, bool) /opt/godot/main/main.cpp:2338:10 (godot.linuxbsd.editor.dev.x86_64.llvm.san+0x3cbcc0d) (BuildId: 77398a27c54674f8)
    #10 main /opt/godot/platform/linuxbsd/godot_linuxbsd.cpp:62:14 (godot.linuxbsd.editor.dev.x86_64.llvm.san+0x3b91df7) (BuildId: 77398a27c54674f8)

  Thread T40 'godot.l:disk$2' (tid=41534, running) created by main thread at:
    #0 pthread_create <null> (godot.linuxbsd.editor.dev.x86_64.llvm.san+0x3b0da76) (BuildId: 77398a27c54674f8)
    #1 <null> <null> (libvulkan_radeon.so+0x44897d) (BuildId: 0162f9f3c2516d03ae83012d794ea26051a87d33)
    #2 RenderingDevice::initialize(ApiContextRD*, bool) /opt/godot/servers/rendering/rendering_device.cpp:4915:36 (godot.linuxbsd.editor.dev.x86_64.llvm.san+0x8e1bcbf) (BuildId: 77398a27c54674f8)
    #3 DisplayServerX11::DisplayServerX11(String const&, DisplayServer::WindowMode, DisplayServer::VSyncMode, unsigned int, Vector2i const*, Vector2i const&, int, Error&) /opt/godot/platform/linuxbsd/x11/display_server_x11.cpp:6198:21 (godot.linuxbsd.editor.dev.x86_64.llvm.san+0x3be87be) (BuildId: 77398a27c54674f8)
    #4 DisplayServerX11::create_func(String const&, DisplayServer::WindowMode, DisplayServer::VSyncMode, unsigned int, Vector2i const*, Vector2i const&, int, Error&) /opt/godot/platform/linuxbsd/x11/display_server_x11.cpp:5348:22 (godot.linuxbsd.editor.dev.x86_64.llvm.san+0x3be5804) (BuildId: 77398a27c54674f8)
    #5 DisplayServer::create(int, String const&, DisplayServer::WindowMode, DisplayServer::VSyncMode, unsigned int, Vector2i const*, Vector2i const&, int, Error&) /opt/godot/servers/display_server.cpp:978:9 (godot.linuxbsd.editor.dev.x86_64.llvm.san+0x87e6993) (BuildId: 77398a27c54674f8)
    #6 Main::setup2() /opt/godot/main/main.cpp:2600:20 (godot.linuxbsd.editor.dev.x86_64.llvm.san+0x3cc0d4b) (BuildId: 77398a27c54674f8)
    #7 Main::setup(char const*, int, char**, bool) /opt/godot/main/main.cpp:2338:10 (godot.linuxbsd.editor.dev.x86_64.llvm.san+0x3cbcc0d) (BuildId: 77398a27c54674f8)
    #8 main /opt/godot/platform/linuxbsd/godot_linuxbsd.cpp:62:14 (godot.linuxbsd.editor.dev.x86_64.llvm.san+0x3b91df7) (BuildId: 77398a27c54674f8)

SUMMARY: ThreadSanitizer: data race (/opt/godot/bin/godot.linuxbsd.editor.dev.x86_64.llvm.san+0x3b42151) (BuildId: 77398a27c54674f8) in pthread_barrier_wait
==================

Minimal reproduction project (MRP)

EmptyProject.zip

[Rubonnek]

Related: #77390