Re: [PATCH] riscv: Enable interrupt during exception handling

[Peter Zijlstra <peterz@infradead.org>]

On Tue, Jun 24, 2025 at 04:11:30PM +0200, Sebastian Andrzej Siewior wrote:
> On 2025-06-24 16:08:15 [+0200], Peter Zijlstra wrote:
> > > >>
> > > >> I also had a series which was doing so for misaligned accesses handling,
> > > >> but after discussion, it was not ok to do so.:
> > > >>
> > > >> https://lore.kernel.org/linux-riscv/20250422094419.GC14170@noisy.programming.kicks-ass.net/
> > > > 
> > > > If I understand that right, exceptions from kernel should be treated as
> > > > NMI, so that lockdep can tell us if exception handlers touch locks.
> > > > 
> > > > But (conditionally) enabling interrupts does not lose us that benefit. It
> > > > is still considered NMI by lockdep.
> > > > 
> > > > Unless I miss something, the patch is fine as is.
> > 
> > I'm confused, you're wanting to conditionally enable interrupts from a
> > kernel exception while its NMI like? *WHY* ?!
> 
> What we want is to enable interrupt handling if it was enabled before
> the exception occured. So we can send a proper signal on PREEMPT_RT
> without chocking on spinlock_t/ sighand.

I'm confused, sending signals is for exception from userspace. That has
nothing to do with exceptions from kernelspace being NMI like.