[GitHub] [incubator-nuttx] antmerlino edited a comment on pull request #1328: [DRAFT] pthread_cleanup functions must be called from user space

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antmerlino edited a comment on pull request #1328:
URL: https://github.com/apache/incubator-nuttx/pull/1328#issuecomment-652509617


   > > There is a complexity... pthread_exit() is also called from within the OS from task_cancelpt.c, pthread_cancel.c, pthread_create.c, sig_default.c, task_cancelpt.c, task_setcancelstate.c, task_setcanceltype.c. This may require another system call analogous to up_pthread_start().
   > 
   > The calls to pthread_exit() from the cancellation logic within the OS is a potential show-stopper. Or certainly a reason to stop and re-consider how thread cancellation should work. Thread cancellation should also be primarily a user-space implementation as well.
   
   @gregory-nutt 
   
   I've now merged my branch in and am ready to put some time towards this.  It sounds like the next big step is to unify the thread cancellation logic - we will definitely need to do some good testing on this!
   
   All of these make sense. I could take care of those.
   
   a. Rename pthread_exit() to nx_pthread_exit(). Remove logic that calls pthread_cleanup() functions.
   b. Make nx_pthread_exit() a system call.
   c. Create libc/pthread/pthread_exit() that contains only i) the logic that calls the pthread_cleanup functions, and ii) calls the nx_pthread_exit() system call.
   d. Extend TLS and pthread-specific data function so that the destructor is retained in TLS
   e. Extend pthread_exit() so that it also calls the pthread-specific data destructors from user-space.
   
   But I feel like we should figure out the cancellation stuff before I do any of that. 
   
   > There is a complexity... pthread_exit() is also called from within the OS from task_cancelpt.c, pthread_cancel.c, pthread_create.c, sig_default.c, task_cancelpt.c, task_setcancelstate.c, task_setcanceltype.c. This may require another system call analagous to up_pthread_start().
   
   I don't really understand what the analogous call would do for us there, could you expand?
   


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