Hi Lan,
Sorry missed this repost! Couple of comments.
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.
> + 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.
--
Thanks and Regards
gautham.
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