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Message-ID: <84564f0f7db4a58ab7cd5314685ca2413c1d7081.camel@svanheule.net>
Subject: Re: [PATCH v2 1/5] lib/test_cpumask: drop cpu_possible_mask full
 test
From:   Sander Vanheule <sander@svanheule.net>
To:     Yury Norov <yury.norov@gmail.com>
Cc:     Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
        Rasmus Villemoes <linux@rasmusvillemoes.dk>,
        Brendan Higgins <brendan.higgins@linux.dev>,
        David Gow <davidgow@google.com>,
        "open list:KERNEL SELFTEST FRAMEWORK" 
        <linux-kselftest@vger.kernel.org>, kunit-dev@googlegroups.com,
        =?ISO-8859-1?Q?Ma=EDra?= Canal <mairacanal@riseup.net>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Date:   Sun, 21 Aug 2022 15:27:56 +0200
In-Reply-To: <CAAH8bW9yZUMn2shYAB1LaDyzgFMYtWCRUXxq=bMCiFys=gzKig@mail.gmail.com>
References: <cover.1661007338.git.sander@svanheule.net>
         <6dfd4d3a4d77f97f13ab3f22bc53c96c38ba908e.1661007339.git.sander@svanheule.net>
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         <9f28529005867512105182f8fa2b0f7b0d14b30d.camel@svanheule.net>
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Hi Yury,

Replying back in plaintext, as you sent an HTML message.

On Sun, 2022-08-21 at 09:18 -0400, Yury Norov wrote:
>=20
>=20
> On Sun, Aug 21, 2022, 09:08 Sander Vanheule <sander@svanheule.net> wrote:
> > Hi Yury,
> >=20
> > On Sat, 2022-08-20 at 14:35 -0700, Yury Norov wrote:
> > > On Sat, Aug 20, 2022 at 05:03:09PM +0200, Sander Vanheule wrote:
> > > > When the number of CPUs that can possibly be brought online is know=
n at
> > > > boot 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 fi=
lled,
> > > > and cpumask_full(cpu_possible_mask) can return false for valid syst=
em
> > > > configurations.
> > >=20
> > > It doesn't mean we can just give up. You can check validity of possib=
le
> > > cpumask like this:=20
> > > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 KUNIT_EXPECT_EQ(test, nr_c=
pu_ids, cpumask_first_zero(&mask_all))
> > > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 KUNIT_EXPECT_EQ(test, NR_C=
PUS, cpumask_first(&mask_all))
> >=20
> > Did you mean cpu_possible_mask, or mask_all?
>=20
> cpu_possble_as of curse.
>=20
> > For cpu_possible_mask, these tests are in test_cpumask_first(), albeit =
under
> > a
> > slightly different form. Together with the tests in test_cpumask_weight=
()
> > and
> > test_cpumask_last(), cpu_possible_mask is already one of the more
> > constrained
> > masks.
> >=20
> >=20
> > For mask_all, the mask is filled up with nr_cpumask_bits <=3D NR_CPUS. =
I could
> > add
> > cpumask_first(), cpumask_first_zero(), and cpumask_last() tests though.
> >=20
> > More tests could be also added for cpu_all_mask, since this does have a=
ll
> > NR_CPUS bits set, but I think that belongs in a separate patch.
> >=20
> > I think the extra mask_all and cpu_all_mask test are out of scope for t=
his
> > patch, but they could be added in another patch (for 6.1).
>=20
> If you think that possible mask is tested by other parts, then can you no=
tice
> that in comments?

Sure, I'll update the commit message to note the other constraints on
cpu_possible_mask.

Best,
Sander