Re: [PATCH -next 0/2] fs/epoll: loosen irq safety when possible

[Peter Zijlstra]

On Sat, Jul 21, 2018 at 10:21:20AM -0700, Davidlohr Bueso wrote:
> On Fri, 20 Jul 2018, Andrew Morton wrote:
> 
> > We could open-code it locally.  Add a couple of
> > WARN_ON_ONCE(irqs_disabled())?  That might need re-benchmarking with
> > Xen but surely just reading the thing isn't too expensive?
> 
> We could also pass on the responsibility to lockdep and just use
> lockdep_assert_irqs_disabled(). But I guess that would be less effective
> than to just open code it in epoll without lockdep -- note that over 80
> places in the kernel do this.

The lockdep thing is relatively recent. I think someone proposed to go
replace a bunch of the open-coded ones at some point.