Re: [PATCH RT 3.18] irq_work: Provide a soft-irq based queue

From: Jan Kiszka
Date: Thu Apr 23 2015 - 02:50:38 EST


On 2015-04-23 08:11, Mike Galbraith wrote:
> @@ -103,6 +98,9 @@ EXPORT_SYMBOL_GPL(irq_work_queue_on);
> /* Enqueue the irq work @work on the current CPU */
> bool irq_work_queue(struct irq_work *work)
> {
> + bool realtime = IS_ENABLED(CONFIG_PREEMPT_RT_FULL);
> + bool raise = false;
> +
> /* Only queue if not already pending */
> if (!irq_work_claim(work))
> return false;
> @@ -110,25 +108,22 @@ bool irq_work_queue(struct irq_work *wor
> /* Queue the entry and raise the IPI if needed. */
> preempt_disable();
>
> -#ifdef CONFIG_PREEMPT_RT_FULL
> - if (work->flags & IRQ_WORK_HARD_IRQ) {
> + if (realtime && (work->flags & IRQ_WORK_HARD_IRQ)) {
> if (llist_add(&work->llnode, this_cpu_ptr(&hirq_work_list)))

This boils down to

#ifdef CONFIG_X
some_type x;
#endif
...

if (IS_ENABLED(CONFIG_X) && ...)
use(x);

And here we even have an indirection for IS_ENABLED via that local bool
variable. Is that pattern OK for Linux? Does it compile in all supported
optimization levels of all supported compilers?

Jan

--
Siemens AG, Corporate Technology, CT RTC ITP SES-DE
Corporate Competence Center Embedded Linux
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