linux-kernel - [PATCH 1/3] cpuidle: If disable_cpuidle() is called, set pm_idle to default

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Message-Id: <1320786914-10541-2-git-send-email-konrad.wilk@oracle.com>
Date:	Tue,  8 Nov 2011 16:15:12 -0500
From:	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
To:	linux-kernel@...r.kernel.org, x86@...nel.org, len.brown@...el.com,
	tglx@...utronix.de, jeremy@...p.org, hpa@...or.com, bp@...en8.de,
	tj@...nel.org, trenn@...e.de
Cc:	mingo@...hat.com, xen-devel@...ts.xensource.com,
	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
	stable@...nel.org
Subject: [PATCH 1/3] cpuidle: If disable_cpuidle() is called, set pm_idle to default_idle.

. however we ignore the disable_cpuidle() directive and
in select_idle_routine() set it to type preferred by the CPU.

This is a regression introduced by

 commit a0bfa1373859e9d11dc92561a8667588803e42d8
 Author: Len Brown <len.brown@...el.com>
 Date:   Fri Apr 1 19:34:59 2011 -0400

     cpuidle: stop depending on pm_idle

specifically this patch:

 commit d91ee5863b71e8c90eaf6035bff3078a85e2e7b5
 Author: Len Brown <len.brown@...el.com>
 Date:   Fri Apr 1 18:28:35 2011 -0400

     cpuidle: replace xen access to x86 pm_idle and default_idle

     ..scribble on pm_idle and access default_idle,
    have it simply disable_cpuidle() so acpi_idle will not load and
    architecture default HLT will be used.

.. but the default HLT does not get used. Instead we end up in the
situation that select_idle_routine() is called from arch/x86/kernel/cpu/common.c
and if we called cpuidle_disable(), then the pm_idle is not set, and
we end up setting pm_idle to mwait_idle or amd_e400_idle.

This patch uses the cpuidle_disabled() functionality and
makes select_idle_routine() adhere to that.

Reported-by: Stefan Bader <stefan.bader@...onical.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>

CC: Thomas Gleixner <tglx@...utronix.de>
CC: Ingo Molnar <mingo@...hat.com>
CC: "H. Peter Anvin" <hpa@...or.com>
CC: x86@...nel.org
CC: Len Brown <len.brown@...el.com>
CC: Borislav Petkov <bp@...en8.de>
CC: Tejun Heo <tj@...nel.org>
CC: Thomas Renninger <trenn@...e.de>
CC: stable@...nel.org
---
 arch/x86/kernel/process.c |    5 +++++
 include/linux/cpuidle.h   |    2 ++
 2 files changed, 7 insertions(+), 0 deletions(-)

diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
index e7e3b01..1f7f8c8 100644
--- a/arch/x86/kernel/process.c
+++ b/arch/x86/kernel/process.c
@@ -14,6 +14,7 @@
 #include <linux/utsname.h>
 #include <trace/events/power.h>
 #include <linux/hw_breakpoint.h>
+#include <linux/cpuidle.h>
 #include <asm/cpu.h>
 #include <asm/system.h>
 #include <asm/apic.h>
@@ -587,6 +588,10 @@ void __cpuinit select_idle_routine(const struct cpuinfo_x86 *c)
 	if (pm_idle)
 		return;
 
+	if (cpuidle_disabled()) {
+		pm_idle = default_idle;
+		return;
+	}
 	if (cpu_has(c, X86_FEATURE_MWAIT) && mwait_usable(c)) {
 		/*
 		 * One CPU supports mwait => All CPUs supports mwait
diff --git a/include/linux/cpuidle.h b/include/linux/cpuidle.h
index b51629e..123fe9e 100644
--- a/include/linux/cpuidle.h
+++ b/include/linux/cpuidle.h
@@ -122,6 +122,7 @@ struct cpuidle_driver {
 };
 
 #ifdef CONFIG_CPU_IDLE
+extern int cpuidle_disabled(void);
 extern void disable_cpuidle(void);
 extern int cpuidle_idle_call(void);
 
@@ -137,6 +138,7 @@ extern int cpuidle_enable_device(struct cpuidle_device *dev);
 extern void cpuidle_disable_device(struct cpuidle_device *dev);
 
 #else
+static inline int cpuidle_disabled(void) { return 1; }
 static inline void disable_cpuidle(void) { }
 static inline int cpuidle_idle_call(void) { return -ENODEV; }
 
-- 
1.7.7.1

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