Re: [PATCH] Priority Lists for the RT mutex

[hui]

On Mon, Apr 11, 2005 at 10:57:37AM +0200, Ingo Molnar wrote:
> 
> * Perez-Gonzalez, Inaky <inaky.perez-gonzalez@xxxxxxxxx> wrote:
> 
> > Let me re-phrase then: it is a must have only on PI, to make sure you 
> > don't have a loop when doing it. Maybe is a consequence of the 
> > algorithm I chose. -However- it should be possible to disable it in 
> > cases where you are reasonably sure it won't happen (such as kernel 
> > code). In any case, AFAIR, I still did not implement it.
> 
> are there cases where userspace wants to disable deadlock-detection for 
> its own locks?

I'd disable it for userspace locks. There might be folks that want to
implement userspace drivers, but I can't imagine it being 'ok' to have
the kernel call out to userspace and have it block correctly. I would
expect them to do something else that's less drastic.
 
> the deadlock detector in PREEMPT_RT is pretty much specialized for 
> debugging (it does all sorts of weird locking tricks to get the first 
> deadlock out, and to really report it on the console), but it ought to 
> be possible to make it usable for userspace-controlled locks as well.

If I understand things correctly, I'd let that be an RT app issue and
the app folks should decided what is appropriate for their setup. If
they need a deadlock detector they should decide on their own protocol.
The kernel debugging issues are completely different.

That's my two cents.

bill

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