linux-kernel - Re: [PATCH v2] kcov: properly check if we are in an interrupt

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Date:   Mon, 10 Oct 2016 16:32:34 -0700
From:   Andrew Morton <akpm@...ux-foundation.org>
To:     Dmitry Vyukov <dvyukov@...gle.com>
Cc:     Andrey Konovalov <andreyknvl@...gle.com>,
        Nicolai Stange <nicstange@...il.com>,
        Andrey Ryabinin <aryabinin@...tuozzo.com>,
        Kees Cook <keescook@...omium.org>,
        James Morse <james.morse@....com>,
        LKML <linux-kernel@...r.kernel.org>,
        Vegard Nossum <vegard.nossum@...cle.com>,
        Quentin Casasnovas <quentin.casasnovas@...cle.com>,
        Andrey Ryabinin <ryabinin.a.a@...il.com>
Subject: Re: [PATCH v2] kcov: properly check if we are in an interrupt

On Mon, 10 Oct 2016 19:19:11 +0200 Dmitry Vyukov <dvyukov@...gle.com> wrote:

> On Mon, Oct 10, 2016 at 6:10 PM, Andrey Konovalov <andreyknvl@...gle.com> wrote:
> > in_interrupt() returns a nonzero value when we are either in an
> > interrupt or have bh disabled via local_bh_disable(). Since we are
> > interested in only ignoring coverage from actual interrupts, do a
> > proper check instead of just calling in_interrupt().
> >
> > Signed-off-by: Andrey Konovalov <andreyknvl@...gle.com>
> 
> FWIW
> Acked-by: Dmitry Vyukov <dvyukov@...gle.com>
> 
> This fixes a very real problem for us.
> As per discussion in v1, other solution would involve auditing all
> uses of in_interrupt() which needs knowledge about all drivers.

OK, but I'm not seeing a description of what the problem *is*.  Could
we please have a complete description of the user-visible effects of this
change, for the changelog?