nested task lock/unlock in rtems?

[Smith, Gene]

Joel Sherrill <joel at OARcorp.com> wrote, On 1/11/2005 11:22 AM:

> Smith, Gene wrote:
> 
>>Can rtems keep track of nested calls to disable/enable preemption?
>>
>>E.g. within a task:
>>
>>lock
>>    lock
>>        lock
>>        unlock
>>    unlock
>>unlock
>>
>>Where preemption is disabled on the first lock and not re-enabled until 
>>the last unlock is called? And lock and unlock could be accomplished by 
>>a call to rtems_task_mode. But is there anything in rtems to ensure a 
>>balance?
> 
> 
> Do you mean via premption via the rtems_task_mode service?


Yes, as documented in the "RTEMS C User's Guide".

> 
> If so, then no.

I can store the nest count in the task notepad value and accomplish what
I want using documented rtems_...() calls. But probably suboptimal.

> 
> If you mean via the critical section routines _Thread_Disable_dispatch
> and friends, then the answer is yes -- a nest count is maintained.

This seems like a more direct way to accomplish what I want. Is it ok to
call these from a user task? I don't see it mentioned in the User's
Guide. It seem to be for internal rtems use. I assume the
"disable/enable dispatch" means stop/start preemption. I am trying to
port this functionality:
http://www.roe.ac.uk/atc/projects/vista/software/VxWorks/docs/vxworks/ref/taskLib.html#taskLock