On Sun, Jun 15, 2025 at 06:35:43PM +0200, Mark Kettenis wrote:
> > From: "Theo de Raadt" <deraadt@openbsd.org>
> > Date: Sun, 15 Jun 2025 10:16:57 -0600
> > 
> > Philip Guenther <guenther@gmail.com> wrote:
> > 
> > > Okay, then I think the original diff is correct, though maybe we add
> > > the assertwaitok() to fpu_kernel_enter() so we remain confident of
> > > that.
> > 
> > If an assert triggers at this point, in drm code, it is unlikely that
> > a user will see it.  I expect it will deadlock the kernel hard in a
> > very invisible fashion...
> 
> Well, assertwaitok() does a few checks.  The first one is:
> 
>     splassert(IPL_NONE);

This does nothing. The code always runs at IPL_NONE or higher.
splassert() always allows a higher SPL.

We need something else to replace all those bogus splassert(IPL_NONE);
checks done.
 
> This is the check we want to make sure that we're not called from
> interrupt context.  By default, this just prints a warning message,
> which shouldn't cause a deadlock.
> 
> There are other checks that may trigger a panic and therefore may
> appear to the user as a deadlock.  So I think it is better to just add
> an splassert(IPL_NONE) into fpu_kernel_enter().
> 

-- 
:wq Claudio