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References: <20230912083800.57435-1-cerasuolodomenico@gmail.com> <20230912101802.25b280ac306694ff02001706@linux-foundation.org>
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From:   Domenico Cerasuolo <cerasuolodomenico@gmail.com>
Date:   Wed, 13 Sep 2023 09:17:12 +0200
Message-ID: <CA+CLi1gtgwa7JZC_NvynOKhM59j_hYpAnc+ivTjXobOqHkQb-A@mail.gmail.com>
Subject: Re: [PATCH] selftests: cgroup: fix test_zswap error path and
 meaningless check
To:     Andrew Morton <akpm@linux-foundation.org>
Cc:     dan.carpenter@linaro.org, kernel-team@meta.com,
        linux-kernel@vger.kernel.org, cgroups@vger.kernel.org,
        linux-kselftest@vger.kernel.org
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On Tue, Sep 12, 2023 at 7:18=E2=80=AFPM Andrew Morton <akpm@linux-foundatio=
n.org> wrote:
>
> On Tue, 12 Sep 2023 10:38:00 +0200 Domenico Cerasuolo <cerasuolodomenico@=
gmail.com> wrote:
>
> > Replace destruction paths with simple returns before the test cgroup is
> > created, there is nothing to free or destroy at that point.
> >
> > Remove pointless check, stored_pages is a size_t and cannot be < 0.
> >
> > ...
> >
> > @@ -208,8 +208,6 @@ static int test_no_kmem_bypass(const char *root)
> >               free(trigger_allocation);
> >               if (get_zswap_stored_pages(&stored_pages))
> >                       break;
> > -             if (stored_pages < 0)
> > -                     break;
> >               /* If memory was pushed to zswap, verify it belongs to me=
mcg */
> >               if (stored_pages > stored_pages_threshold) {
> >                       int zswapped =3D cg_read_key_long(test_group, "me=
mory.stat", "zswapped ");
>
> stored_pages will be set to -1 on error.  It would be better to cast
> stored_pages to ssize_t in the check, rather than simply ignoring
> errors?

I'm not sure I understood, isn't it safe to just rely on the return value o=
f
get_zswap_stored_pages a few lines above? In that case we break the loop an=
d
the value of stored_pages is not used.