Re: [PATCH 1/2] lockdep: improve current->(hard|soft)irqs_enabled synchronisation with actual irq state

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:

quoted

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).