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Date:   Wed, 12 Aug 2020 12:35:30 +0200
From:   peterz@infradead.org
To:     Nicholas Piggin <npiggin@gmail.com>
Cc:     Alexey Kardashevskiy <aik@ozlabs.ru>, linux-arch@vger.kernel.org,
        linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
        Ingo Molnar <mingo@redhat.com>, Will Deacon <will@kernel.org>
Subject: Re: [PATCH 1/2] lockdep: improve current->(hard|soft)irqs_enabled
 synchronisation with actual irq state
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On Wed, Aug 12, 2020 at 06:18:28PM +1000, Nicholas Piggin wrote:
> Excerpts from peterz@infradead.org's message of August 7, 2020 9:11 pm:
> > 
> > What's wrong with something like this?
> > 
> > AFAICT there's no reason to actually try and add IRQ tracing here, it's
> > just a hand full of instructions at the most.
> 
> Because we may want to use that in other places as well, so it would
> be nice to have tracing.
> 
> Hmm... also, I thought NMI context was free to call local_irq_save/restore
> anyway so the bug would still be there in those cases?

NMI code has in_nmi() true, in which case the IRQ tracing is disabled
(except for x86 which has CONFIG_TRACE_IRQFLAGS_NMI).