On Wed, Dec 09, 2020 at 01:27:10PM +0000, Mark Rutland wrote:
> On Sun, Nov 22, 2020 at 01:44:53PM -0800, Andy Lutomirski wrote:
> > On Sat, Nov 21, 2020 at 10:55 PM Jürgen Groß <jgross@xxxxxxxx> wrote:
> > > On 20.11.20 12:59, Peter Zijlstra wrote:
> > > > If someone were to write horrible code like:
> > > >
> > > > local_irq_disable();
> > > > local_irq_save(flags);
> > > > local_irq_enable();
> > > > local_irq_restore(flags);
> > > >
> > > > we'd be up some creek without a paddle... now I don't _think_ we have
> > > > genius code like that, but I'd feel saver if we can haz an assertion in
> > > > there somewhere...
> I was just talking to Peter on IRC about implementing the same thing for
> arm64, so could we put this in the generic irqflags code? IIUC we can
> use raw_irqs_disabled() to do the check.
>
> As this isn't really entry specific (and IIUC the cases this should
> catch would break lockdep today), maybe we should add a new
> DEBUG_IRQFLAGS for this, that DEBUG_LOCKDEP can also select?
>
> Something like:
>
> #define local_irq_restore(flags) \
> do { \
> if (!raw_irqs_disabled_flags(flags)) { \
> trace_hardirqs_on(); \
> } else if (IS_ENABLED(CONFIG_DEBUG_IRQFLAGS) { \
> if (unlikely(raw_irqs_disabled()) \
Whoops; that should be !raw_irqs_disabled().
> warn_bogus_irqrestore(); \
> } \
> raw_local_irq_restore(flags); \
> } while (0)
>
> ... perhaps? (ignoring however we deal with once-ness).
If no-one shouts in the next day or two I'll spin this as its own patch.
Mark.
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