linux-kernel - Re: [PATCH v8 6/6] cpufreq: powernv: Add sysfs attributes to show throttle stats

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Message-ID: <56B1BD71.2050403@linux.vnet.ibm.com>
Date:	Wed, 03 Feb 2016 14:12:25 +0530
From:	Shilpasri G Bhat <shilpa.bhat@...ux.vnet.ibm.com>
To:	Viresh Kumar <viresh.kumar@...aro.org>
CC:	linuxppc-dev@...abs.org, linux-kernel@...r.kernel.org,
	rjw@...ysocki.net, linux-pm@...r.kernel.org, pc@...ibm.com,
	anton@...ba.org, ego@...ux.vnet.ibm.com,
	shreyas@...ux.vnet.ibm.com, bsingharora@...il.com,
	mpe@...erman.id.au, linux-api@...r.kernel.org
Subject: Re: [PATCH v8 6/6] cpufreq: powernv: Add sysfs attributes to show
 throttle stats

Hi,

On 02/03/2016 01:57 PM, Viresh Kumar wrote:
> On 03-02-16, 01:11, Shilpasri G Bhat wrote:
>>  static int init_chip_info(void)
>>  {
>>  	unsigned int chip[256];
>> -	unsigned int cpu, i;
>> +	unsigned int cpu;
>>  	unsigned int prev_chip_id = UINT_MAX;
>>  	cpumask_t cpu_mask;
>> -	int ret = -ENOMEM;
>> +	int i, j, ret = -ENOMEM;
>>  
>>  	core_to_chip_map = kcalloc(cpu_nr_cores(), sizeof(unsigned int),
>>  				   GFP_KERNEL);
>> @@ -583,12 +711,51 @@ static int init_chip_info(void)
>>  		goto free_chip_map;
>>  
>>  	for (i = 0; i < nr_chips; i++) {
>> +		char name[10];
>> +
>>  		chips[i].id = chip[i];
>>  		cpumask_copy(&chips[i].mask, cpumask_of_node(chip[i]));
>>  		INIT_WORK(&chips[i].throttle, powernv_cpufreq_work_fn);
>> +
>> +		for (j = 0; j <= OCC_MAX_THROTTLE_STATUS; j++) {
>> +			chips[i].reason[j] =
>> +			     kcalloc(powernv_pstate_info.nr_pstates,
>> +				     sizeof(int), GFP_KERNEL);
>> +			if (!chips[i].reason[j]) {
>> +				ret = -ENOMEM;
>> +				goto free_chip;
>> +			}
>> +		}
>> +
>> +		snprintf(name, sizeof(name), "chip%d", chips[i].id);
>> +		ret = kobject_init_and_add(&chips[i].kobj,
>> +					   get_ktype(cpufreq_global_kobject),
> 
> Sorry but why do you need to create a kobject here ? A simple
> sysfs_create_group() can create groups (directories) for you.

I need the chip-id in the <attr>_show(). With just sysfs_create_group() I will
get the cpufreq_global_kobject in the <attr>_show() and I will not be able to
figure out the chip-id.

Thanks and Regards,
Shilpa
> 
>> +					   cpufreq_global_kobject, name);
>> +		if (ret)
>> +			goto free_chip;
>> +
>> +		ret = sysfs_create_group(&chips[i].kobj, &throttle_stat_group);
>> +		if (ret) {
>> +			pr_info("Chip %d failed to create throttle sysfs group\n",
>> +				chips[i].id);
>> +			goto free_kobject;
>> +		}
>>  	}
>