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

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Message-ID: <20180721172120.kbdu4euc2wn4xzgf@linux-r8p5>
Date:   Sat, 21 Jul 2018 10:21:20 -0700
From:   Davidlohr Bueso <dave@...olabs.net>
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     jbaron@...mai.com, viro@...iv.linux.org.uk,
        linux-kernel@...r.kernel.org,
        Peter Zijlstra <a.p.zijlstra@...llo.nl>
Subject: Re: [PATCH -next 0/2] fs/epoll: loosen irq safety when possible

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.

Thanks,
Davidlohr