About Thread_Cancel

[Richi Dubey]

Hi,

Thanks for the help.

What is the contradiction? You shouldn't have a blocked thread in a
> queue when you want to delete it. The thread needs to be in some kind
> of "quiescent" state.

Okay, I'll look further into this.

On Wed, Feb 24, 2021 at 10:19 PM Gedare Bloom <gedare at rtems.org> wrote:

> On Wed, Feb 24, 2021 at 12:54 AM Richi Dubey <richidubey at gmail.com> wrote:
> >
> > Hi,
> >
> > Can someone please give a brief overview of what these three lines aim
> to achieve:
> >
> >   } else if ( _Thread_Is_life_change_allowed( previous ) ) {
> >     _Thread_Add_life_change_request( the_thread );
> >     _Thread_State_release( the_thread, &lock_context );
> >
> >     _Thread_Finalize_life_change( the_thread, priority );
> >
> > 492 threadrestart.c
> >
> > I am asking because in line 92 of sp02, this _Thread_Cancel function is
> called, and because of _Thread_Add_life_change_request( the_thread )
> ->_Thread_Set_state_locked -> _Scheduler_Block is called and because of
> _Thread_Finalize_life_change->_Thread_Remove_life_change_request->_Thread_Clear_state_locked->_Scheduler_Unblock
> is called, which is contradictory.
> >
> What is the contradiction? You shouldn't have a blocked thread in a
> queue when you want to delete it. The thread needs to be in some kind
> of "quiescent" state.
>
> Thread cancellation and end-of-life considerations are tricky. Maybe
> your scheduler has some invalid assumptions about how threads
> terminate?
>
> The API-level requirements derive from two directions:
>
> https://docs.rtems.org/branches/master/c-user/scheduling-concepts/background.html#task-state-transitions
>
> https://docs.rtems.org/branches/master/posix-users/thread_cancellation.html
>
> The low-level detailed implementation is probably not so
> well-documented. You might be able to find some clues in the doxygen.
> Otherwise you probably have to keep working your way through the code
> like you have been.
>
> > Thanks,
> > Richi.
> > _______________________________________________
> > devel mailing list
> > devel at rtems.org
> > http://lists.rtems.org/mailman/listinfo/devel
>
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