linux-kernel - Re: [PATCH v2 11/13] selftests/resctrl: Convert ctrlgrp & mongrp to pointers

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Date: Fri, 22 Mar 2024 10:44:32 -0700
From: Reinette Chatre <reinette.chatre@...el.com>
To: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
CC: <linux-kselftest@...r.kernel.org>, Shuah Khan <shuah@...nel.org>, "Babu
 Moger" <babu.moger@....com>, Maciej Wieczór-Retman
	<maciej.wieczor-retman@...el.com>, Fenghua Yu <fenghua.yu@...el.com>, LKML
	<linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 11/13] selftests/resctrl: Convert ctrlgrp & mongrp to
 pointers

Hi Ilpo,

On 3/22/2024 5:30 AM, Ilpo Järvinen wrote:
> On Wed, 20 Mar 2024, Reinette Chatre wrote:
>> On 3/11/2024 6:52 AM, Ilpo Järvinen wrote:
>>> The struct resctrl_val_param has control and monitor groups as char
>>> arrays but they are not supposed to be mutated within resctrl_val().
>>>
>>> Convert the ctrlgrp and mongrp char array within resctrl_val_param to
>>> plain const char pointers and adjust the strlen() based checks to
>>> check NULL instead.
>>>
>>> Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
>>> ---
>>>  tools/testing/selftests/resctrl/resctrl.h   | 4 ++--
>>>  tools/testing/selftests/resctrl/resctrlfs.c | 8 ++++----
>>>  2 files changed, 6 insertions(+), 6 deletions(-)
>>>
>>> diff --git a/tools/testing/selftests/resctrl/resctrl.h b/tools/testing/selftests/resctrl/resctrl.h
>>> index 52769b075233..54e5bce4c698 100644
>>> --- a/tools/testing/selftests/resctrl/resctrl.h
>>> +++ b/tools/testing/selftests/resctrl/resctrl.h
>>> @@ -89,8 +89,8 @@ struct resctrl_test {
>>>   */
>>>  struct resctrl_val_param {
>>>  	char		*resctrl_val;
>>> -	char		ctrlgrp[64];
>>> -	char		mongrp[64];
>>> +	const char	*ctrlgrp;
>>> +	const char	*mongrp;
>>>  	char		filename[64];
>>>  	unsigned long	mask;
>>>  	int		num_of_runs;
>>> diff --git a/tools/testing/selftests/resctrl/resctrlfs.c b/tools/testing/selftests/resctrl/resctrlfs.c
>>> index 79cf1c593106..dbe0cc6d74fa 100644
>>> --- a/tools/testing/selftests/resctrl/resctrlfs.c
>>> +++ b/tools/testing/selftests/resctrl/resctrlfs.c
>>> @@ -469,7 +469,7 @@ static int create_grp(const char *grp_name, char *grp, const char *parent_grp)
>>>  	 * length of grp_name == 0, it means, user wants to use root con_mon
>>>  	 * grp, so do nothing
>>>  	 */
>>
>> Could you please confirm that the comments are still accurate?
> 
> It's not, I missed it.
> 
>>> -	if (strlen(grp_name) == 0)
>>> +	if (!grp_name)
>>>  		return 0;
> 
> But now when looking into the surrounding code, to me it looks the correct 
> action here is to remove the comment and return -1 instead of 0. It makes
> this just an internal sanity check that grp_name is provided by the 
> caller.
> 

hmmm ... this should not be an error because the caller is not required
to provide grp_name. Not providing grp_name has a specific meaning
of this operating on the CON_MON group and a failure would break flows
operating on the CON_MON group.

Reinette