On 2014年09月17日 17:03, Gautham R Shenoy wrote:
> Hi Lan,
>
> Sorry missed this repost! Couple of comments.
>
Np, Thanks for review :)
> On Fri, Aug 22, 2014 at 04:33:40PM +0800, Lan Tianyu wrote:
>
> [.. snip ..]
>>
>> +static int _cpu_up_with_trace(int cpu)
>> +{
>> + int error;
>> +
>> + trace_suspend_resume(TPS("CPU_ON"), cpu, true);
>> + error = _cpu_up(cpu, 1);
>> + trace_suspend_resume(TPS("CPU_ON"), cpu, false);
>> + if (error) {
>> + pr_warn("Error taking CPU%d up: %d\n", cpu, error);
>> + return error;
>> + }
>> +
>> + pr_info("CPU%d is up\n", cpu);
>> + return 0;
>> +}
>> +
>> +static int async_enable_nonboot_cpus(void *data)
>> +{
>> + int cpu;
>> +
>> + cpu_maps_update_begin();
>> + arch_enable_nonboot_cpus_begin();
>> +
>> + for_each_cpu(cpu, frozen_cpus) {
>> + _cpu_up_with_trace(cpu);
>> + }
>> +
>> + arch_enable_nonboot_cpus_end();
>> + cpumask_clear(frozen_cpus);
>> + cpu_maps_update_done();
>> + return 0;
>> +}
>> +
>> void __ref enable_nonboot_cpus(void)
>> {
>> + struct task_struct *tsk;
>> int cpu, error;
>>
>> /* Allow everyone to use the CPU hotplug again */
>> @@ -563,22 +597,34 @@ void __ref enable_nonboot_cpus(void)
>>
>> pr_info("Enabling non-boot CPUs ...\n");
>>
>> - arch_enable_nonboot_cpus_begin();
>> + cpu = cpumask_first(frozen_cpus);
>> + cpumask_clear_cpu(cpu, frozen_cpus);
>>
>> - for_each_cpu(cpu, frozen_cpus) {
>> - trace_suspend_resume(TPS("CPU_ON"), cpu, true);
>> - error = _cpu_up(cpu, 1);
>> - trace_suspend_resume(TPS("CPU_ON"), cpu, false);
>> - if (!error) {
>> - pr_info("CPU%d is up\n", cpu);
>> - continue;
>> + error = _cpu_up_with_trace(cpu);
>
> If cpu fails to come up, you need to add a pr_warn() citing the
> reason why it failed to come up.
Ok.
>
>
>> + if (cpumask_empty(frozen_cpus))
>> + goto out;
>> +
>> + if (error) {
>> + /*
>> + * If fail to bring up the first frozen cpus,
>> + * enable the rest frozen cpus on the boot cpu.
>> + */
>> + arch_enable_nonboot_cpus_begin();
>> + for_each_cpu(cpu, frozen_cpus) {
>> + _cpu_up_with_trace(cpu);
>> }
>> - pr_warn("Error taking CPU%d up: %d\n", cpu, error);
>> - }
>> + arch_enable_nonboot_cpus_end();
>>
>> - arch_enable_nonboot_cpus_end();
>> + } else {
>> + tsk = kthread_create_on_cpu(async_enable_nonboot_cpus,
>> + NULL, cpu, "async-enable-nonboot-cpus");
>> + if (IS_ERR(tsk)) {
>> + pr_err("Failed to create async enable nonboot cpus
>> thread.\n");
>> + goto out;
>
> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ This is not good. If you fail to
> create a kthread on the first non-boot cpu, that means none of the
> other non-boot cpus will be brought up.
>
> Hence you might want to consider reordering the code in such a manner
> that if the first non-boot cpu fails to come up or if you fail to
> create the kthread task, then the boot cpu will boot the remaining non
> boot cpus.
Yes, this sounds good and will do it in the new version.
>
> --
> Thanks and Regards
> gautham.
>
--
Best regards
Tianyu Lan
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