linux-kernel - Re: [PATCH 03/11] kasan: clean up comments in tests

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Date:   Tue, 12 Jan 2021 18:55:53 +0100
From:   Andrey Konovalov <andreyknvl@...gle.com>
To:     Alexander Potapenko <glider@...gle.com>
Cc:     Catalin Marinas <catalin.marinas@....com>,
        Vincenzo Frascino <vincenzo.frascino@....com>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        Marco Elver <elver@...gle.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Will Deacon <will.deacon@....com>,
        Andrey Ryabinin <aryabinin@...tuozzo.com>,
        Evgenii Stepanov <eugenis@...gle.com>,
        Branislav Rankov <Branislav.Rankov@....com>,
        Kevin Brodsky <kevin.brodsky@....com>,
        kasan-dev <kasan-dev@...glegroups.com>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        Linux Memory Management List <linux-mm@...ck.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 03/11] kasan: clean up comments in tests

On Tue, Jan 12, 2021 at 8:53 AM Alexander Potapenko <glider@...gle.com> wrote:
>
> On Tue, Jan 5, 2021 at 7:28 PM Andrey Konovalov <andreyknvl@...gle.com> wrote:
> >
> > Clarify and update comments and info messages in KASAN tests.
> >
> > Signed-off-by: Andrey Konovalov <andreyknvl@...gle.com>
> > Link: https://linux-review.googlesource.com/id/I6c816c51fa1e0eb7aa3dead6bda1f339d2af46c8
>
> >  void *kasan_ptr_result;
> >  int kasan_int_result;
> Shouldn't these two variables be static, by the way?

No, then the compiler starts eliminating accesses.

> > @@ -39,14 +38,13 @@ static struct kunit_resource resource;
> >  static struct kunit_kasan_expectation fail_data;
> >  static bool multishot;
> >
> > +/*
> > + * Temporarily enable multi-shot mode. Otherwise, KASAN would only report the
> > + * first detected bug and panic the kernel if panic_on_warn is enabled.
> > + */
>
> YMMV, but I think this comment was at its place already.

It gets updated by one of the subsequent patches.

> >  static int kasan_test_init(struct kunit *test)
> >  {
> > -       /*
> > -        * Temporarily enable multi-shot mode and set panic_on_warn=0.
> > -        * Otherwise, we'd only get a report for the first case.
> > -        */
> >         multishot = kasan_save_enable_multi_shot();
>
> Unrelated to this change, but have you considered storing
> test-specific data in test->priv instead of globals?

I'd say that test->priv is for some per-test data that's used in the
tests, and multishot is not a part of that.

> >         if (!IS_ENABLED(CONFIG_SLUB)) {
> > -               kunit_info(test, "CONFIG_SLUB is not enabled.");
> > +               kunit_info(test, "skipping, CONFIG_SLUB required");
> >                 return;
> >         }
>
> You may want to introduce a macro that takes a config name and prints
> the warning/returns if it's not enabled.

Good idea, will do in v2.

Thanks!