* Jacob Pan [off-list ref] wrote:

From: Peter Zijlstra <peterz@infradead.org>

Idle injection drivers such as Intel powerclamp and ACPI PAD drivers use
realtime tasks to take control of CPU then inject idle. There are two issues
with this approach:

'CPU' is capitalized properly here.

And here:

 #define PF_VCPU		0x00000010	/* I'm a virtual CPU */

But not later in the patch.

Sloppy formulation: how can the idle task be inherited? Also, capitalize comments 
please.

+	/*
+	 * If the arch has a polling bit, we maintain an invariant:
+	 *
+	 * Our polling bit is clear if we're not scheduled (i.e. if
+	 * rq->curr != rq->idle).  This means that, if rq->idle has
+	 * the polling bit set, then setting need_resched is
+	 * guaranteed to cause the cpu to reschedule.
+	 */

'CPU' is not properly capitalized here.

+	/* In poll mode we reenable interrupts and spin.
+	 * Also if we detected in the wakeup from idle
+	 * path that the tick broadcast device expired
+	 * for us, we don't want to go deep idle as we
+	 * know that the IPI is going to arrive right
+	 * away
+	 */
+		if (cpu_idle_force_poll || tick_check_broadcast_expired())
+			cpu_idle_poll();
+		else
+			cpuidle_idle_call();
+		arch_cpu_idle_exit();

Sigh: that's not standard comment style, nor is it standard coding style.

Also, multi-sentence comments should end with a full stop.

+	/*
+	 * We promise to call sched_ttwu_pending and reschedule
+	 * if need_resched is set while polling is set.  That
+	 * means that clearing polling needs to be visible
+	 * before doing these things.
+	 */

When referring to functions in comments please spell them as "fn()", i.e. with 
parentheses.

+	/*
+	 * If duration is 0, we will return after a natural wake event occurs. If
+	 * duration is none zero, we will go back to sleep if we were woken up earlier.
+	 * We also set up a timer to make sure we don't oversleep in deep idle.
+	 */
+	if (!duration_ms)
+		do_idle();
+	else {
+		hrtimer_init_on_stack(&timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
+		timer.function = idle_inject_timer_fn;
+		hrtimer_start(&timer, ms_to_ktime(duration_ms),
+			HRTIMER_MODE_REL_PINNED);
+		end_time = jiffies + msecs_to_jiffies(duration_ms);
+
+		while (time_after(end_time, jiffies))
+			do_idle();
+	}

Curly braces should be balanced and nonsensical line breaks should be omitted.

Also, comments should be read and grammar should be fixed.

Thanks,

	Ingo