Helgrind: Possible data race in SdlVideo.cc

[JohnSmithBH84]

Helgrind detected a data race in SdlVideo.cc:262 after launching doom64ex. I'm not sure whether this is an actual issue, or whether Doom64EX' code is too sophisticated for Helgrind to understand. Do you guys have any idea?

Project version

Doom64EX: (master a5a8ccb)
clang: 19.1.0 (x86_64-unknown-linux-gnu)

Operating system

Ubuntu 22.04.4 LTS
Linux 5.15.0-125-generic #135-Ubuntu SMP Fri Sep 27 13:53:58 UTC 2024 x86_64 x86_64 x86_64 GNU/Linux

I did this

Configured and build the project.

mkdir build & cd build
cmake -DCMAKE_BUILD_TYPE=DEBUG -Wno-dev ..
cmake --build . -- -j16

Launched executable without arguments.
valgrind --tool=helgrind ./Doom64EX/build/doom64ex

I expected the following

No data race reported by Helgrind

I got the following

= ----------------------------------------------------------------
==3303== 
==3303==  Lock at 0x974CAE0 was first observed
==3303==    at 0x80D2EA9: pthread_mutex_init (hg_intercepts.c:818)
==3303==    by 0x822B2B1: ??? (in /usr/lib/x86_64-linux-gnu/libSDL2-2.0.so.0.2600.5)
==3303==    by 0x814E374: ??? (in /usr/lib/x86_64-linux-gnu/libSDL2-2.0.so.0.2600.5)
==3303==    by 0x811A29B: ??? (in /usr/lib/x86_64-linux-gnu/libSDL2-2.0.so.0.2600.5)
==3303==    by 0x23ABF8: SdlVideo::SdlVideo(imp::OpenGLVer) (SdlVideo.cc:262)
==3303==    by 0x239D0A: init_video_sdl() (SdlVideo.cc:546)
==3303==    by 0x2395C1: I_InitScreen() (i_video.cc:49)
==3303==    by 0x239662: I_InitVideo() (i_video.cc:113)
==3303==    by 0x2391C3: I_Init() (i_system.cc:278)
==3303==    by 0x1B6C87: D_DoomMain() (d_main.cc:994)
==3303==    by 0x19302E: imp::app::main(int, char**) (App.cc:144)
==3303==    by 0x193615: main (App.cc:219)
==3303==  Address 0x974cae0 is 0 bytes inside a block of size 40 alloc'd
==3303==    at 0x80CD62F: calloc (vg_replace_malloc.c:1328)
==3303==    by 0x8187860: ??? (in /usr/lib/x86_64-linux-gnu/libSDL2-2.0.so.0.2600.5)
==3303==    by 0x822B284: ??? (in /usr/lib/x86_64-linux-gnu/libSDL2-2.0.so.0.2600.5)
==3303==    by 0x814E374: ??? (in /usr/lib/x86_64-linux-gnu/libSDL2-2.0.so.0.2600.5)
==3303==    by 0x811A29B: ??? (in /usr/lib/x86_64-linux-gnu/libSDL2-2.0.so.0.2600.5)
==3303==    by 0x23ABF8: SdlVideo::SdlVideo(imp::OpenGLVer) (SdlVideo.cc:262)
==3303==    by 0x239D0A: init_video_sdl() (SdlVideo.cc:546)
==3303==    by 0x2395C1: I_InitScreen() (i_video.cc:49)
==3303==    by 0x239662: I_InitVideo() (i_video.cc:113)
==3303==    by 0x2391C3: I_Init() (i_system.cc:278)
==3303==    by 0x1B6C87: D_DoomMain() (d_main.cc:994)
==3303==    by 0x19302E: imp::app::main(int, char**) (App.cc:144)
==3303==  Block was alloc'd by thread #1
==3303== 
==3303== Possible data race during write of size 8 at 0x82BA588 by thread #1
==3303== Locks held: 1, at address 0x974CAE0
==3303==    at 0x811BE9E: ??? (in /usr/lib/x86_64-linux-gnu/libSDL2-2.0.so.0.2600.5)
==3303==    by 0x814A53B: ??? (in /usr/lib/x86_64-linux-gnu/libSDL2-2.0.so.0.2600.5)
==3303==    by 0x814E31F: ??? (in /usr/lib/x86_64-linux-gnu/libSDL2-2.0.so.0.2600.5)
==3303==    by 0x811A29B: ??? (in /usr/lib/x86_64-linux-gnu/libSDL2-2.0.so.0.2600.5)
==3303==    by 0x23ABF8: SdlVideo::SdlVideo(imp::OpenGLVer) (SdlVideo.cc:262)
==3303==    by 0x239D0A: init_video_sdl() (SdlVideo.cc:546)
==3303==    by 0x2395C1: I_InitScreen() (i_video.cc:49)
==3303==    by 0x239662: I_InitVideo() (i_video.cc:113)
==3303==    by 0x2391C3: I_Init() (i_system.cc:278)
==3303==    by 0x1B6C87: D_DoomMain() (d_main.cc:994)
==3303==    by 0x19302E: imp::app::main(int, char**) (App.cc:144)
==3303==    by 0x193615: main (App.cc:219)
==3303== 
==3303== This conflicts with a previous read of size 8 by thread #3
==3303== Locks held: none
==3303==    at 0x811BBEC: ??? (in /usr/lib/x86_64-linux-gnu/libSDL2-2.0.so.0.2600.5)
==3303==    by 0x822AD8F: ??? (in /usr/lib/x86_64-linux-gnu/libSDL2-2.0.so.0.2600.5)
==3303==    by 0x81E7213: ??? (in /usr/lib/x86_64-linux-gnu/libSDL2-2.0.so.0.2600.5)
==3303==    by 0x8189084: ??? (in /usr/lib/x86_64-linux-gnu/libSDL2-2.0.so.0.2600.5)
==3303==    by 0x822AB78: ??? (in /usr/lib/x86_64-linux-gnu/libSDL2-2.0.so.0.2600.5)
==3303==    by 0x80D17D6: mythread_wrapper (hg_intercepts.c:406)
==3303==    by 0x86C01C3: start_thread (pthread_create.c:442)
==3303==    by 0x873FABF: clone (clone.S:100)
==3303==  Address 0x82ba588 is in the BSS segment of /usr/lib/x86_64-linux-gnu/libSDL2-2.0.so.0.2600.5
==3303== 
==3303== ----------------------------------------------------------------