[tip:sched/core] sched/idle: Move the cpuidle entry point to the generic idle loop

tip-bot for Nicolas Pitre
2014-02-11T12:19:42Z

Commit-ID: af8cd8ef726f335815233d03b8723e9c52041edd
Gitweb: http://git.kernel.org/tip/af8cd8ef726f335815233d03b8723e9c52041edd
Author: Nicolas Pitre <nicolas.pitre@linaro.org>
AuthorDate: Wed, 29 Jan 2014 15:31:36 -0500
Committer: Ingo Molnar <mingo@kernel.org>
CommitDate: Tue, 11 Feb 2014 09:58:20 +0100

sched/idle: Move the cpuidle entry point to the generic idle loop

In order to integrate cpuidle with the scheduler, we must have a better
proximity in the core code with what cpuidle is doing and not delegate
such interaction to arch code.

Architectures implementing arch_cpu_idle() should simply enter
a cheap idle mode in the absence of a proper cpuidle driver.

In both cases i.e. whether it is a cpuidle driver or the default
arch_cpu_idle(), the calling convention expects IRQs to be disabled
on entry and enabled on exit. There is a warning in place already but
let's add a forced IRQ enable here as well. This will allow for
removing the forced IRQ enable some implementations do locally and
allowing for the warning to trig.

Signed-off-by: Nicolas Pitre <nico@linaro.org>
Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Olof Johansson <olof@lixom.net>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/alpine.LFD.2.11.1401291526320.1652@knanqh.ubzr
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
kernel/cpu/idle.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/kernel/cpu/idle.c b/kernel/cpu/idle.c
index 277f494..b7976a1 100644
--- a/kernel/cpu/idle.c
+++ b/kernel/cpu/idle.c
@@ -3,6 +3,7 @@
*/
#include <linux/sched.h>
#include <linux/cpu.h>
+#include <linux/cpuidle.h>
#include <linux/tick.h>
#include <linux/mm.h>
#include <linux/stackprotector.h>
@@ -95,8 +96,10 @@ static void cpu_idle_loop(void)
if (!current_clr_polling_and_test()) {
stop_critical_timings();
rcu_idle_enter();
- arch_cpu_idle();
- WARN_ON_ONCE(irqs_disabled());
+ if (cpuidle_idle_call())
+ arch_cpu_idle();
+ if (WARN_ON_ONCE(irqs_disabled()))
+ local_irq_enable();
rcu_idle_exit();
start_critical_timings();
} else {