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Message-ID: <20140414092547.GJ13658@twins.programming.kicks-ass.net>
Date: Mon, 14 Apr 2014 11:25:47 +0200
From: Peter Zijlstra <peterz@...radead.org>
To: Nicolas Pitre <nicolas.pitre@...aro.org>
Cc: mingo@...nel.org, tglx@...utronix.de, luto@...capital.net,
daniel.lezcano@...aro.org, umgwanakikbuti@...il.com,
linux-kernel@...r.kernel.org
Subject: Re: [RFC][PATCH 8/8] sched,idle: Reflow cpuidle_idle_call()
On Mon, Apr 14, 2014 at 10:59:11AM +0200, Peter Zijlstra wrote:
> > Why not using braces here and moving the use_default code block inside
> > it instead?
>
> I didn't because there's two goto use_default sites, but sure, I can do
> that.
---
Subject: sched,idle: Reflow cpuidle_idle_call()
From: Peter Zijlstra <peterz@...radead.org>
Date: Fri Apr 11 13:55:48 CEST 2014
Apply goto to reduce lines and nesting levels.
Cc: Nicolas Pitre <nicolas.pitre@...aro.org>
Cc: Daniel Lezcano <daniel.lezcano@...aro.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Signed-off-by: Peter Zijlstra <peterz@...radead.org>
Link: http://lkml.kernel.org/n/tip-xt260n72av3ip7jsaef2ps3h@git.kernel.org
---
kernel/sched/idle.c | 131 +++++++++++++++++++++++-----------------------------
1 file changed, 58 insertions(+), 73 deletions(-)
--- a/kernel/sched/idle.c
+++ b/kernel/sched/idle.c
@@ -73,7 +73,7 @@ static int cpuidle_idle_call(void)
{
struct cpuidle_device *dev = __this_cpu_read(cpuidle_devices);
struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
- int next_state, entered_state, ret;
+ int next_state, entered_state;
bool broadcast;
/*
@@ -102,90 +102,75 @@ static int cpuidle_idle_call(void)
* Check if the cpuidle framework is ready, otherwise fallback
* to the default arch specific idle method
*/
- ret = cpuidle_enabled(drv, dev);
-
- if (!ret) {
- /*
- * Ask the governor to choose an idle state it thinks
- * it is convenient to go to. There is *always* a
- * convenient idle state
- */
- next_state = cpuidle_select(drv, dev);
-
+ if (cpuidle_enabled(drv, dev)) {
+use_default:
/*
- * The idle task must be scheduled, it is pointless to
- * go to idle, just update no idle residency and get
- * out of this function
+ * We can't use the cpuidle framework, let's use the default
+ * idle routine.
*/
- if (current_clr_polling_and_test()) {
- dev->last_residency = 0;
- entered_state = next_state;
+ if (current_clr_polling_and_test())
local_irq_enable();
- } else {
- broadcast = !!(drv->states[next_state].flags &
- CPUIDLE_FLAG_TIMER_STOP);
-
- if (broadcast) {
- /*
- * Tell the time framework to switch
- * to a broadcast timer because our
- * local timer will be shutdown. If a
- * local timer is used from another
- * cpu as a broadcast timer, this call
- * may fail if it is not available
- */
- ret = clockevents_notify(
- CLOCK_EVT_NOTIFY_BROADCAST_ENTER,
- &dev->cpu);
- }
-
- if (!ret) {
- trace_cpu_idle_rcuidle(next_state, dev->cpu);
-
- /*
- * Enter the idle state previously
- * returned by the governor
- * decision. This function will block
- * until an interrupt occurs and will
- * take care of re-enabling the local
- * interrupts
- */
- entered_state = cpuidle_enter(drv, dev,
- next_state);
-
- trace_cpu_idle_rcuidle(PWR_EVENT_EXIT,
- dev->cpu);
-
- if (broadcast)
- clockevents_notify(
- CLOCK_EVT_NOTIFY_BROADCAST_EXIT,
- &dev->cpu);
-
- /*
- * Give the governor an opportunity to reflect on the
- * outcome
- */
- cpuidle_reflect(dev, entered_state);
- }
- }
+ else
+ arch_cpu_idle();
+
+ goto exit_idle;
}
/*
- * We can't use the cpuidle framework, let's use the default
- * idle routine
+ * Ask the governor to choose an idle state it thinks
+ * it is convenient to go to. There is *always* a
+ * convenient idle state
*/
- if (ret) {
- if (!current_clr_polling_and_test())
- arch_cpu_idle();
- else
- local_irq_enable();
+ next_state = cpuidle_select(drv, dev);
+
+ /*
+ * The idle task must be scheduled, it is pointless to
+ * go to idle, just update no idle residency and get
+ * out of this function
+ */
+ if (current_clr_polling_and_test()) {
+ dev->last_residency = 0;
+ entered_state = next_state;
+ local_irq_enable();
+ goto exit_idle;
}
+ broadcast = !!(drv->states[next_state].flags & CPUIDLE_FLAG_TIMER_STOP);
+
+ /*
+ * Tell the time framework to switch to a broadcast timer
+ * because our local timer will be shutdown. If a local timer
+ * is used from another cpu as a broadcast timer, this call may
+ * fail if it is not available
+ */
+ if (broadcast &&
+ clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_ENTER, &dev->cpu))
+ goto use_default;
+
+ trace_cpu_idle_rcuidle(next_state, dev->cpu);
+
+ /*
+ * Enter the idle state previously returned by the governor decision.
+ * This function will block until an interrupt occurs and will take
+ * care of re-enabling the local interrupts
+ */
+ entered_state = cpuidle_enter(drv, dev, next_state);
+
+ trace_cpu_idle_rcuidle(PWR_EVENT_EXIT, dev->cpu);
+
+ if (broadcast)
+ clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_EXIT, &dev->cpu);
+
+ /*
+ * Give the governor an opportunity to reflect on the outcome
+ */
+ cpuidle_reflect(dev, entered_state);
+
+exit_idle:
__current_set_polling();
/*
- * It is up to the idle functions to enable back the local
- * interrupt
+ * It is up to the idle functions to reenable local interrupts
*/
if (WARN_ON_ONCE(irqs_disabled()))
local_irq_enable();
--
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