Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
MIME-Version: 1.0
References: <20230717113709.328671-1-glider@google.com> <20230717113709.328671-3-glider@google.com>
 <ZLVoRkmy5IZYbjUV@yury-ThinkPad>
In-Reply-To: <ZLVoRkmy5IZYbjUV@yury-ThinkPad>
From:   Alexander Potapenko <glider@google.com>
Date:   Mon, 17 Jul 2023 18:42:47 +0200
Message-ID: <CAG_fn=XnyrYwMdM5i-KqpaxW0xG+vFs3h3nipKePe8yTo23Eug@mail.gmail.com>
Subject: Re: [PATCH v3 2/5] lib/test_bitmap: add tests for bitmap_{set,get}_value()
To:     Yury Norov <yury.norov@gmail.com>
Cc:     catalin.marinas@arm.com, will@kernel.org, pcc@google.com,
        andreyknvl@gmail.com, andriy.shevchenko@linux.intel.com,
        linux@rasmusvillemoes.dk, linux-kernel@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org, eugenis@google.com,
        syednwaris@gmail.com, william.gray@linaro.org
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
Precedence: bulk

On Mon, Jul 17, 2023 at 6:11=E2=80=AFPM Yury Norov <yury.norov@gmail.com> w=
rote:
>
> On Mon, Jul 17, 2023 at 01:37:05PM +0200, Alexander Potapenko wrote:
> > Add basic tests ensuring that values can be added at arbitrary position=
s
> > of the bitmap, including those spanning into the adjacent unsigned
> > longs.
> >
> > Signed-off-by: Alexander Potapenko <glider@google.com>
>
> Thanks for the test!
>
> > ---
> > This patch was previously called
> > "lib/test_bitmap: add tests for bitmap_{set,get}_value_unaligned"
> >
> > v3:
> >  - switch to using bitmap_{set,get}_value()
> >  - change the expected bit pattern in test_set_get_value(),
> >    as the test was incorrectly assuming 0 is the LSB.
> > ---
> >  lib/test_bitmap.c | 33 +++++++++++++++++++++++++++++++++
> >  1 file changed, 33 insertions(+)
> >
> > diff --git a/lib/test_bitmap.c b/lib/test_bitmap.c
> > index 187f5b2db4cf1..c2ab54040c249 100644
> > --- a/lib/test_bitmap.c
> > +++ b/lib/test_bitmap.c
> > @@ -71,6 +71,17 @@ __check_eq_uint(const char *srcfile, unsigned int li=
ne,
> >       return true;
> >  }
> >
> > +static bool __init
> > +__check_eq_ulong(const char *srcfile, unsigned int line,
> > +              const unsigned long exp_ulong, unsigned long x)
> > +{
> > +     if (exp_ulong !=3D x) {
> > +             pr_err("[%s:%u] expected %lu, got %lu\n",
> > +                     srcfile, line, exp_ulong, x);
> > +             return false;
> > +     }
> > +     return true;
> > +}
> >
> >  static bool __init
> >  __check_eq_bitmap(const char *srcfile, unsigned int line,
> > @@ -186,6 +197,7 @@ __check_eq_str(const char *srcfile, unsigned int li=
ne,
> >       })
> >
> >  #define expect_eq_uint(...)          __expect_eq(uint, ##__VA_ARGS__)
> > +#define expect_eq_ulong(...)         __expect_eq(ulong, ##__VA_ARGS__)
> >  #define expect_eq_bitmap(...)                __expect_eq(bitmap, ##__V=
A_ARGS__)
> >  #define expect_eq_pbl(...)           __expect_eq(pbl, ##__VA_ARGS__)
> >  #define expect_eq_u32_array(...)     __expect_eq(u32_array, ##__VA_ARG=
S__)
> > @@ -1222,6 +1234,25 @@ static void __init test_bitmap_const_eval(void)
> >       BUILD_BUG_ON(~var !=3D ~BIT(25));
> >  }
> >
> > +static void __init test_set_get_value(void)
> > +{
> > +     DECLARE_BITMAP(bitmap, BITS_PER_LONG * 2);
>
> It's too short. Can you make it long enough to ensure it works as
> expected when start is not in the 1st word, and start+nbits is in
> the following word.
>
> > +     unsigned long val;
> > +     int i;
> > +
> > +     for (i =3D 0; i < BITS_PER_LONG * 2 - 7; i++) {
> > +             bitmap_zero(bitmap, BITS_PER_LONG * 2);
> > +             bitmap_set_value(bitmap, 0b10101UL, i, 5);
> > +             val =3D bitmap_get_value(bitmap, i, 5);
> > +             expect_eq_ulong(0b10101UL, val);
>
> Can you also check that the rest of bitmap is untouched?
> Something like:
>
>         DECLARE_BITMAP(bitmap, ...);
>         DECLARE_BITMAP(orig, ...);
>
>         memset(orig, 0x5a, ...);
>         memset(bitmap, 0x5a, ...);
>
>         for (j =3D start; j < start + nbits; j++)
>                 if (val & BIT(j - start))
>                         __set_bit(j, orig);
>                 else
>                         __clear_bit(j, orig);
>
>         bitmap_set_value(bitmap, val, start, nbits);
>         expect_eq_bitmap(orig, bitmap, ...);
>
> I like this kind of testing because it gives people a better
> understanding of what happens behind all that optimization tricks.

Will do. In fact the difference between GENMASK(n, 0) and GENMASK(n-1,
0) discussed in the other patch requires exactly this kind of testing.