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From: =?UTF-8?q?Ilpo=20J=C3=A4rvinen?= <ilpo.jarvinen@linux.intel.com>
Date: Wed, 31 Jan 2024 14:04:57 +0200 (EET)
To: Maciej Wieczor-Retman <maciej.wieczor-retman@intel.com>
cc: Reinette Chatre <reinette.chatre@intel.com>, fenghua.yu@intel.com, 
    shuah@kernel.org, LKML <linux-kernel@vger.kernel.org>, 
    linux-kselftest@vger.kernel.org
Subject: Re: [PATCH v3 2/5] selftests/resctrl: Add helpers for the non-contiguous
 test
In-Reply-To: <tck7kcpjdch3a3qkkwusft5zwptlhtmicx53zjcqk3x42w5p55@pf6vrmnh7deo>
Message-ID: <6259e494-bab3-0aeb-0bf6-e4e384f8f0b0@linux.intel.com>
References: <cover.1706180726.git.maciej.wieczor-retman@intel.com> <85b1efc3ddd698b3ac81aa72a6dc987ee17da3e2.1706180726.git.maciej.wieczor-retman@intel.com> <ea9b0e06-c07e-eb4b-9e7d-ed20419b677d@linux.intel.com> <611fd2b6-d9ec-42f0-9711-b1398fc02842@intel.com>
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On Wed, 31 Jan 2024, Maciej Wieczor-Retman wrote:
> On 2024-01-26 at 10:58:04 -0800, Reinette Chatre wrote:
> >On 1/25/2024 4:14 AM, Ilpo J=E4rvinen wrote:
> >> On Thu, 25 Jan 2024, Maciej Wieczor-Retman wrote:
> >
> >>> +=09fp =3D fopen(file_path, "r");
> >>> +=09if (!fp) {
> >>> +=09=09snprintf(reason, sizeof(reason), "Error in opening %s file\n",=
 filename);
> >>> +=09=09ksft_perror(reason);
> >>=20
> >> Was this the conclusion of the kstf_perror() discussion with Reinette?=
 I=20
> >> expected a bit different outcome when I stopped following it...
> >>=20
> >> In any case, it would be nice though if ksft_perror() (or some kselfte=
st.h=20
> >> function yet to be added with a different name) would accept full prin=
tf=20
> >> interface and just add the errno string into the end of the string so =
one=20
> >> would not need to build constructs like this at all.
> >>=20
> >> It will require a bit of macro trickery into kselftest.h. I don't know=
 how=20
> >> it should handle the case where somebody just passes a char pointer to=
 it,=20
> >> not a string literal, but I guess it would just throw an error while=
=20
> >> compiling if somebody tries to do that as the macro string literal=20
> >> concatenation could not build useful/compilable token.
> >>=20
> >> It would make these prints informative enough to become actually usefu=
l=20
> >> without needed to resort to preparing the string in advance which seem=
s
> >> to be required almost every single case with the current interface.
> >
> >I think this can be accomplished with a new:
> >=09void  ksft_vprint_msg(const char *msg, va_list args)
> >
> >... but ksft_perror() does conform to perror() and I expect that having =
one
> >support variable number of arguments while the other does to cause confu=
sion.
> >
> >To support variable number of arguments with errno I'd propose just to u=
se
> >ksft_print_msg() with strerror(errno), errno as the arguments (or even %=
m
> >that that errno handling within ksft_print_msg() aims to support). This =
does
> >indeed seem to be the custom in other tests.
>=20
> Does something like this look okay?
>=20
> =09fp =3D fopen(file_path, "r");
> =09if (!fp) {
> =09=09ksft_print_msg("Error in opening %s\n: %m\n", file_path);
> =09=09return -1;
> =09}
>=20
> The '%m' seems to work fine but doesn't print errno's number code. Do you=
 want
> me to add errno after '%m' so it is the same as ksft_perror()? I looked t=
hrough
> some other tests where '%m' is used, and only few ones add errno with '%d=
'.

I think %m is enough.

--=20
 i.

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