On 03/22/2013 03:23 AM, Thomas Gleixner wrote:
> All idle functions in arch/* are more or less the same, plus minus a
> few bugs and extra instrumentation, tickless support and other
> optional items.
>
> Implement a generic idle function which resembles the functionality
> found in arch/. Provide weak arch_cpu_idle_* functions which can be
> overridden by the architecture code if needed.
>
> Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> ---
> arch/Kconfig | 3 +
> include/linux/cpu.h | 8 +++
> kernel/cpu/idle.c | 105 ++++++++++++++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 116 insertions(+)
[...]
> +
> +/*
> + * Generic idle loop implementation
> + */
> +static void cpu_idle_loop(void)
> +{
> + while (1) {
> + tick_nohz_idle_enter();
> +
> + while (!need_resched()) {
> + check_pgt_cache();
> + rmb();
> +
> + if (cpu_is_offline(smp_processor_id()))
> + arch_cpu_idle_dead();
> +
> + local_irq_disable();
> + arch_cpu_idle_enter();
> +
> + if (cpu_idle_force_poll) {
> + cpu_idle_poll();
> + } else {
> + current_clr_polling();
> + if (!need_resched()) {
> + stop_critical_timings();
> + rcu_idle_enter();
> + arch_cpu_idle();
> + WARN_ON_ONCE(!irqs_disabled());
I understand that you have changed it to WARN_ON_ONCE(irqs_disabled()) in
the v2 hosted in your git tree..
Sometime ago, Deepthi (in CC) had added such a check and Rafael had faced
some weird problems with that, and hence it was removed. Below are some
links to that discussion.
https://lkml.org/lkml/2012/6/22/48
https://lkml.org/lkml/2012/6/24/132
https://lkml.org/lkml/2012/6/25/402
Rafael, do you still see that problem after applying Thomas' patches?
> + rcu_idle_exit();
> + start_critical_timings();
> + } else {
> + local_irq_enable();
> + }
> + current_set_polling();
> + }
> + arch_cpu_idle_exit();
> + }
> + tick_nohz_idle_exit();
> + schedule_preempt_disabled();
> + }
> +}
> +
> +void cpu_startup_entry(enum cpuhp_state state)
> +{
> + current_set_polling();
> + arch_cpu_idle_prepare();
> + cpu_idle_loop();
> +}
> +#endif
>
>
Regards,
Srivatsa S. Bhat
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