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Message-ID: <4f334657f927865266fee19a7920f7248a111ef8.camel@svanheule.net>
Subject: Re: [PATCH v1 1/5] lib/test_cpumask: drop cpu_possible_mask full
 test
From:   Sander Vanheule <sander@svanheule.net>
To:     David Gow <davidgow@google.com>
Cc:     Yury Norov <yury.norov@gmail.com>,
        Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
        Rasmus Villemoes <linux@rasmusvillemoes.dk>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        =?ISO-8859-1?Q?Ma=EDra?= Canal <mairacanal@riseup.net>
Date:   Wed, 10 Aug 2022 10:45:35 +0200
In-Reply-To: <CABVgOSmcKHH2zcCbT-jzekFP8RFov4V0AFBsGjU9kXSy9pJ9HQ@mail.gmail.com>
References: <cover.1660068429.git.sander@svanheule.net>
         <30d8882efedea697da20c27563050008d1569b9e.1660068429.git.sander@svanheule.net>
         <CABVgOSmcKHH2zcCbT-jzekFP8RFov4V0AFBsGjU9kXSy9pJ9HQ@mail.gmail.com>
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Hi David,

On Wed, 2022-08-10 at 12:06 +0800, David Gow wrote:
> On Wed, Aug 10, 2022 at 2:09 AM Sander Vanheule <sander@svanheule.net> wr=
ote:
> >=20
> > cpu_possible_mask is not necessarily completely filled.=C2=A0 That mean=
s
> > running a check on cpumask_full() doesn't make sense, so drop the test.
> >=20
> > Fixes: c41e8866c28c ("lib/test: introduce cpumask KUnit test suite")
> > Link: https://lore.kernel.org/lkml/346cb279-8e75-24b0-7d12-9803f2b41c73=
@riseup.net/
> > Reported-by: Ma=C3=ADra Canal <mairacanal@riseup.net>
> > Signed-off-by: Sander Vanheule <sander@svanheule.net>
> > Cc: David Gow <davidgow@google.com>
> > ---
>=20
> Looks good to me. It'd maybe be worth noting _why_=C2=A0 cpu_possible_mas=
k
> is not always filled (i.e., that the number of available CPUs might
> not match the maximum number of CPUs the kernel is built to support),
> but it's probably not worth doing a new version of the patch series
> just for that.
>=20
> Reviewed-by: David Gow <davidgow@google.com>

Thanks for the reviews!

Perhaps the commit message could be replaced by:

"When the number of CPUs that can possibly be brought online is known at bo=
ot time, e.g. when
HOTPLUG is disabled, nr_cpu_ids may be smaller than NR_CPUS. In that case, =
cpu_possible_mask would
not be completely filled, and cpumask_full(cpu_possible_mask) may return fa=
lse for valid system
configurations."


Best,
Sander

>=20
> Cheers,
> -- David
>=20
>=20
> > =C2=A0lib/test_cpumask.c | 1 -
> > =C2=A01 file changed, 1 deletion(-)
> >=20
> > diff --git a/lib/test_cpumask.c b/lib/test_cpumask.c
> > index a31a1622f1f6..4ebf9f5805f3 100644
> > --- a/lib/test_cpumask.c
> > +++ b/lib/test_cpumask.c
> > @@ -54,7 +54,6 @@ static cpumask_t mask_all;
> > =C2=A0static void test_cpumask_weight(struct kunit *test)
> > =C2=A0{
> > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 KUNIT_EXPECT_TRUE(test, cpum=
ask_empty(&mask_empty));
> > -=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 KUNIT_EXPECT_TRUE(test, cpumask_f=
ull(cpu_possible_mask));
> > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 KUNIT_EXPECT_TRUE(test, cpum=
ask_full(&mask_all));
> >=20
> > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 KUNIT_EXPECT_EQ(test, 0, cpu=
mask_weight(&mask_empty));
> > --
> > 2.37.1
> >=20