linux-kernel - Re: [PATCH v5 4/5] selftests/resctrl: Cleanup properly when an error occurs in CAT test

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Date:   Mon, 23 Jan 2023 09:36:13 -0800
From:   Reinette Chatre <reinette.chatre@...el.com>
To:     "Shaopeng Tan (Fujitsu)" <tan.shaopeng@...itsu.com>,
        Fenghua Yu <fenghua.yu@...el.com>,
        Shuah Khan <shuah@...nel.org>
CC:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-kselftest@...r.kernel.org" <linux-kselftest@...r.kernel.org>
Subject: Re: [PATCH v5 4/5] selftests/resctrl: Cleanup properly when an error
 occurs in CAT test

Hi Shaopeng,

On 1/22/2023 8:22 PM, Shaopeng Tan (Fujitsu) wrote:
>> On 1/10/2023 11:58 PM, Shaopeng Tan wrote:

...

>>> diff --git a/tools/testing/selftests/resctrl/cat_test.c
>>> b/tools/testing/selftests/resctrl/cat_test.c
>>> index 6a8306b0a109..87302b882929 100644
>>> --- a/tools/testing/selftests/resctrl/cat_test.c
>>> +++ b/tools/testing/selftests/resctrl/cat_test.c
>>> @@ -103,7 +103,6 @@ int cat_perf_miss_val(int cpu_no, int n, char
>> *cache_type)
>>>  	unsigned long l_mask, l_mask_1;
>>>  	int ret, pipefd[2], sibling_cpu_no;
>>>  	char pipe_message;
>>> -	pid_t bm_pid;
>>>
>>>  	cache_size = 0;
>>>
>>> @@ -181,28 +180,29 @@ int cat_perf_miss_val(int cpu_no, int n, char
>> *cache_type)
>>>  		strcpy(param.filename, RESULT_FILE_NAME1);
>>>  		param.num_of_runs = 0;
>>>  		param.cpu_no = sibling_cpu_no;
>>> +	} else {
>>> +		ret = signal_handler_register();
>>> +		if (ret)
>>> +			goto out;
>>
>> The "goto" will unregister the signal handler. Is that necessary if the registration
>> failed?
>>
>> Also, if signal_handler_register() fails then the child will keep running and run
>> its test ... would child not then run forever?
> 
> A signal handler is needed here, but it is rarely used.
> Also, the registration rarely fails.
> Therefore, if registration failed, 
> just print a warning/info message as follow.
> how about this idea?
> 
> ksft_print_msg("Failed to register signal handler, signals SIGINT/SIGTERM/SIGHUP will not be handled as expected");
> 

I do not think this is necessary considering that signal_handler_register()
already prints an error on failure. 

Adding an error message does not address the two issues I raised.

Reinette