[PATCH 05/18] cpuidle: make a single register function for all

[daniel.lezcano@linaro.org (Daniel Lezcano)]

On 04/10/2013 04:59 PM, Rob Herring wrote:
> On 04/10/2013 09:22 AM, Daniel Lezcano wrote:
>> The usual scheme to initialize a cpuidle driver on a SMP is:
>>
>> 	cpuidle_register_driver(drv);
>> 	for_each_possible_cpu(cpu) {
>> 		device = &per_cpu(cpuidle_dev, cpu);
>> 		cpuidle_register_device(device);
>> 	}
>>
>> This code is duplicated in each cpuidle driver.
>>
>> On UP systems, it is done this way:
>>
>> 	cpuidle_register_driver(drv);
>> 	device = &per_cpu(cpuidle_dev, cpu);
>> 	cpuidle_register_device(device);
>>
>> On UP, the macro 'for_each_cpu' does one iteration:
>>
>> #define for_each_cpu(cpu, mask)                 \
>>         for ((cpu) = 0; (cpu) < 1; (cpu)++, (void)mask)
>>
>> Hence, the initialization loop is the same for UP than SMP.
>>
>> Beside, we saw different bugs / mis-initialization / return code unchecked in
>> the different drivers, the code is duplicated including bugs. After fixing all
>> these ones, it appears the initialization pattern is the same for everyone.
>>
>> Let's add a wrapper function doing this initialization with a cpumask parameter
>> for the coupled idle states and use it for all the drivers.
>>
>> That will save a lot of LOC, consolidate the code, and the modifications in the
>> future could be done in a single place. Another benefit is the consolidation of
>> the cpuidle_device variable which is now in the cpuidle framework and no longer
>> spread accross the different arch specific drivers.
>>
>> Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
>> ---
> 
> Perhaps my ack was too quick...
> 
>> +int cpuidle_register(struct cpuidle_driver *drv,
>> +		     const struct cpumask *const coupled_cpus)
>> +{
>> +	int ret, cpu;
>> +	struct cpuidle_device *device;
>> +
>> +	ret = cpuidle_register_driver(drv);
>> +	if (ret) {
>> +		printk(KERN_ERR "failed to register cpuidle driver\n");
>> +		return ret;
>> +	}
>> +
>> +	for_each_possible_cpu(cpu) {
>> +		device = &per_cpu(cpuidle_dev, cpu);
>> +		device->cpu = cpu;
>> +#ifdef CONFIG_ARCH_NEEDS_CPU_IDLE_COUPLED
>> +		device->coupled_cpus = *coupled_cpus;
> 
> This needs a NULL check. CONFIG_ARCH_NEEDS_CPU_IDLE_COUPLED is most
> likely going to be enabled with multi-platform kernels and this will crash.

Good point, I will fix it.

> Also, I think typically struct copies have a note that it is copy.
> 
> Rob
> 


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