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Bug 4097

Summary: Segmentation fault by SDL_CreateThreadWithStackSize.
Product: SDL Reporter: Dongsun Kim <keinb2>
Component: threadAssignee: Sam Lantinga <slouken>
Status: RESOLVED FIXED QA Contact: Sam Lantinga <slouken>
Severity: normal    
Priority: P2    
Version: 2.0.7   
Hardware: ARM   
OS: Other   

Description Dongsun Kim 2018-02-26 02:11:15 UTC 
Normal case
1. [thread 1] SDL_CreateThreadWithStackSize calls SDL_SYS_CreateThread.
2. [thread 1] If successful, it calls SDL_SemWait.
3. [thread 2] SDL_RunThread calls SDL_SYS_SetupThread, SDL_ThreadID, SDL_SemPost.
4. [thread 1] SDL_CreateThreadWithStackSize calls SDL_DestroySemaphore, SDL_free.

Crash case (Segmentation fault)
1. [thread 1] SDL_CreateThreadWithStackSize calls SDL_SYS_CreateThread.
2. [thread 1] If successful, it calls SDL_SemWait.
--> Error return due to SIGNAL(SYSTEM or Real Time) at sem_wait(pthread).
3. [thread 1] SDL_CreateThreadWithStackSize calls SDL_DestroySemaphore, SDL_free.
4. [thread 2] SDL_RunThread calls SDL_SYS_SetupThread, SDL_ThreadID, SDL_SemPost.
--> Segmentation fault at strlen or sem_post.
Comment 1 Sam Lantinga 2018-02-26 02:40:34 UTC 
Makes sense, do you have a patch you can test with that repro case?
Comment 2 Dongsun Kim 2018-02-26 03:05:23 UTC 
Yes I can test it.
My application use SIG38 for synchronization.
Sometime it makes crash.

But using SDL_SemWaitTimeout was OK because it has below loop.
    do {
        retval = sem_timedwait(&sem->sem, &ts_timeout);
    } while (retval < 0 && errno == EINTR);
Comment 3 Sam Lantinga 2018-02-26 03:50:35 UTC 
Okay, that looks like a good change.
https://hg.libsdl.org/SDL/rev/29bf3038a246

Thanks!