Re: [PATCH] sparc/pci: Make pci_poke_lock a raw_spinlock_t.

[Sebastian Andrzej Siewior <bigeasy@linutronix.de>]

On 2024-11-27 08:02:50 [-0800], Guenter Roeck wrote:
> On 11/27/24 07:39, Andreas Larsson wrote:
> > Even though this is for sparc64, there is work being done looking into
> > enabling RT for sparc32. If the amount of fixes needed to keep
> > PROVE_RAW_LOCK_NESTING enabled is quite small at the moment I'd rather
> > see it enabled for sparc rather than risking it becoming worse in the
> > future.

Okay. So you seem to be in favour of fixing the sparc64 splats Guenter
reported?

> > I don't know what the situation is for other architectures that does not
> > support RT.
> > 
> 
> For my part I still don't understand why PROVE_RAW_LOCK_NESTING is no longer
> a configurable option, or in other words why it is mandated even for architectures
> not supporting RT. To me this means that I'll either have to disable PROVE_LOCKING
> for sparc or live with endless warning backtraces. The latter obscures real
> problems, so it is a no-go.

It is documented in Documentation/locking/locktypes.rst how the locks
should nest. It is just nobody enabled it on sparc64 and tested. The
option was meant temporary until the big read blocks are cleared.

> So, if people want to keep mandating PROVE_RAW_LOCK_NESTING together with
> PROVE_LOCKING for all architectures, I'll disable PROVE_LOCKING for sparc
> in my testing. NP, just let me know. I'll then do the same for other
> architectures not supporting RT if I hit the same problem there.

Waiman posted a patch to disable it on architectures that don't support
PREEMPT_RT. You could also post the patches you discussed. Andreas does
not seem to be against it (but then I don't know if he is a 32 or 64bit
guy). I did not year from other architectures so far.

> Guenter

Sebastian