On Fri, 11 Apr 2014, Peter Zijlstra wrote:
> With the generic idle functions assuming !polling we should only clear
> the polling bit at the very last opportunity in order to avoid
> spurious IPIs.
>
> Ideally we'd flip the default to polling, but that means auditing all
> arch idle functions.
>
> Cc: Nicolas Pitre <nicolas.pi...@linaro.org>
> Cc: Daniel Lezcano <daniel.lezc...@linaro.org>
> Cc: Thomas Gleixner <t...@linutronix.de>
> Signed-off-by: Peter Zijlstra <pet...@infradead.org>
Acked-by: Nicolas Pitre <n...@linaro.org>
> ---
> kernel/sched/idle.c | 17 ++++++++++-------
> 1 file changed, 10 insertions(+), 7 deletions(-)
>
> --- a/kernel/sched/idle.c
> +++ b/kernel/sched/idle.c
> @@ -78,12 +78,10 @@ static int cpuidle_idle_call(void)
>
> /*
> * Check if the idle task must be rescheduled. If it is the
> - * case, exit the function after re-enabling the local irq and
> - * set again the polling flag
> + * case, exit the function after re-enabling the local irq.
> */
> - if (current_clr_polling_and_test()) {
> + if (need_resched()) {
> local_irq_enable();
> - __current_set_polling();
> return 0;
> }
>
> @@ -127,7 +125,7 @@ static int cpuidle_idle_call(void)
> broadcast = !!(drv->states[next_state].flags &
> CPUIDLE_FLAG_TIMER_STOP);
>
> - if (broadcast)
> + if (broadcast) {
> /*
> * Tell the time framework to switch
> * to a broadcast timer because our
> @@ -139,6 +137,7 @@ static int cpuidle_idle_call(void)
> ret = clockevents_notify(
> CLOCK_EVT_NOTIFY_BROADCAST_ENTER,
> &dev->cpu);
> + }
>
> if (!ret) {
> trace_cpu_idle_rcuidle(next_state, dev->cpu);
> @@ -175,8 +174,12 @@ static int cpuidle_idle_call(void)
> * We can't use the cpuidle framework, let's use the default
> * idle routine
> */
> - if (ret)
> - arch_cpu_idle();
> + if (ret) {
> + if (!current_clr_polling_and_test())
> + arch_cpu_idle();
> + else
> + local_irq_enable();
> + }
>
> __current_set_polling();
>
>
>
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
