[0/4] pm_idle, default_idle cleanup

[0/4] pm_idle, default_idle cleanup

[Len Brown]

The 1st three patches in this series are specific to x86.
With an ack from the x86 crew (the main patch still has Ingo's ack
from 16 months ago) I think they could be 3.6-rc1 cleanup candidates.

The 4th patch is enabled by the first 3 -- removing pm_idle() from pm.h
touches 10 architectures.  That one will need a bunch of acks and
post rc1 linux-next build testing to make sure it doesn't break 3.7.

thanks,
Len Brown, Intel Open Source Technology Center

[PATCH 1/4] Revert "x86 idle APM: deprecate CONFIG_APM_CPU_IDLE" to prepare for actual removal

[Len Brown]

From: Len Brown <len.brown@intel.com>

Remove warning that perplex users about removal of CONFIG_APM_CPU_IDLE in 2012.
This allows applying the original removal patch cleanly.

In retrospect, adding this warning was a mistake.
We should have shipped the removal patch 16 months ago.

cc: x86@kernel.org
cc: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Len Brown <len.brown@intel.com>
---
 Documentation/feature-removal-schedule.txt | 10 ++++++++++
 arch/x86/kernel/apm_32.c                   |  2 ++
 2 files changed, 12 insertions(+)

diff --git a/Documentation/feature-removal-schedule.txt b/Documentation/feature-removal-schedule.txt
index 5540615..fc505c1 100644
--- a/Documentation/feature-removal-schedule.txt
+++ b/Documentation/feature-removal-schedule.txt
@@ -14,6 +14,16 @@ Who:	Len Brown <len.brown@intel.com>

 ---------------------------

+What:	CONFIG_APM_CPU_IDLE, and its ability to call APM BIOS in idle
+When:	2012
+Why:	This optional sub-feature of APM is of dubious reliability,
+	and ancient APM laptops are likely better served by calling HLT.
+	Deleting CONFIG_APM_CPU_IDLE allows x86 to stop exporting
+	the pm_idle function pointer to modules.
+Who:	Len Brown <len.brown@intel.com>
+
+----------------------------
+
 What:	x86_32 "no-hlt" cmdline param
 When:	2012

diff --git a/arch/x86/kernel/apm_32.c b/arch/x86/kernel/apm_32.c
index 0e4f24c..4c4ac32 100644
--- a/arch/x86/kernel/apm_32.c
+++ b/arch/x86/kernel/apm_32.c
@@ -359,6 +359,7 @@ struct apm_user {
  * idle percentage above which bios idle calls are done
  */
 #ifdef CONFIG_APM_CPU_IDLE
+#warning deprecated CONFIG_APM_CPU_IDLE will be deleted in 2012
 #define DEFAULT_IDLE_THRESHOLD	95
 #else
 #define DEFAULT_IDLE_THRESHOLD	100
@@ -902,6 +903,7 @@ static void apm_cpu_idle(void)
 	unsigned int jiffies_since_last_check = jiffies - last_jiffies;
 	unsigned int bucket;

+	WARN_ONCE(1, "deprecated apm_cpu_idle will be deleted in 2012");
 recalc:
 	if (jiffies_since_last_check > IDLE_CALC_LIMIT) {
 		use_apm_idle = 0;
--
1.7.12.rc0

Signed-off-by: Len Brown <len.brown@intel.com>
---
 Documentation/feature-removal-schedule.txt | 10 ----------
 arch/x86/kernel/apm_32.c                   |  2 --
 2 files changed, 12 deletions(-)

diff --git a/Documentation/feature-removal-schedule.txt b/Documentation/feature-removal-schedule.txt
index 56000b3..bb4f9e0 100644
--- a/Documentation/feature-removal-schedule.txt
+++ b/Documentation/feature-removal-schedule.txt
@@ -13,16 +13,6 @@ Who:	Jim Cromie <jim.cromie@gmail.com>, Jason Baron <jbaron@redhat.com>
 
 ---------------------------
 
-What:	CONFIG_APM_CPU_IDLE, and its ability to call APM BIOS in idle
-When:	2012
-Why:	This optional sub-feature of APM is of dubious reliability,
-	and ancient APM laptops are likely better served by calling HLT.
-	Deleting CONFIG_APM_CPU_IDLE allows x86 to stop exporting
-	the pm_idle function pointer to modules.
-Who:	Len Brown <len.brown@intel.com>
-
-----------------------------
-
 What:	x86_32 "no-hlt" cmdline param
 When:	2012
 Why:	remove a branch from idle path, simplify code used by everybody.
diff --git a/arch/x86/kernel/apm_32.c b/arch/x86/kernel/apm_32.c
index 07b0c0d..3a89ca3 100644
--- a/arch/x86/kernel/apm_32.c
+++ b/arch/x86/kernel/apm_32.c
@@ -358,7 +358,6 @@ struct apm_user {
  * idle percentage above which bios idle calls are done
  */
 #ifdef CONFIG_APM_CPU_IDLE
-#warning deprecated CONFIG_APM_CPU_IDLE will be deleted in 2012
 #define DEFAULT_IDLE_THRESHOLD	95
 #else
 #define DEFAULT_IDLE_THRESHOLD	100
@@ -902,7 +901,6 @@ static void apm_cpu_idle(void)
 	unsigned int jiffies_since_last_check = jiffies - last_jiffies;
 	unsigned int bucket;
 
-	WARN_ONCE(1, "deprecated apm_cpu_idle will be deleted in 2012");
 recalc:
 	if (jiffies_since_last_check > IDLE_CALC_LIMIT) {
 		use_apm_idle = 0;
-- 
1.7.12.rc0

[PATCH 2/4] x86 idle APM: delete apm_cpu_idle()

[Len Brown]

From: Len Brown <len.brown@intel.com>

The APM idle feature to call into the BIOS
is known to break some machines, and it has dubious benefit
on the (decades old) machines it doesn't break.

After this patch, systems running in APM mode will
simply run default_idle() and HALT, rather than calling
into the BIOS from their idle loop.

This also deletes the last modular use use of (pm_idle)()
and default_idle().

Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Len Brown <len.brown@intel.com>
---
 arch/x86/Kconfig         |  11 ---
 arch/x86/kernel/apm_32.c | 232 -----------------------------------------------
 2 files changed, 243 deletions(-)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index c70684f..7da1e35 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -1847,17 +1847,6 @@ config APM_DO_ENABLE
 	  T400CDT. This is off by default since most machines do fine without
 	  this feature.
 
-config APM_CPU_IDLE
-	bool "Make CPU Idle calls when idle"
-	---help---
-	  Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
-	  On some machines, this can activate improved power savings, such as
-	  a slowed CPU clock rate, when the machine is idle. These idle calls
-	  are made after the idle loop has run for some length of time (e.g.,
-	  333 mS). On some machines, this will cause a hang at boot time or
-	  whenever the CPU becomes idle. (On machines with more than one CPU,
-	  this option does nothing.)
-
 config APM_DISPLAY_BLANK
 	bool "Enable console blanking using APM"
 	---help---
diff --git a/arch/x86/kernel/apm_32.c b/arch/x86/kernel/apm_32.c
index 3a89ca3..31b4196 100644
--- a/arch/x86/kernel/apm_32.c
+++ b/arch/x86/kernel/apm_32.c
@@ -175,8 +175,6 @@
  *         Ignore first resume after we generate our own resume event
  *         after a suspend (Thomas Hood)
  *         Daemonize now gets rid of our controlling terminal (sfr).
- *         CONFIG_APM_CPU_IDLE now just affects the default value of
- *         idle_threshold (sfr).
  *         Change name of kernel apm daemon (as it no longer idles) (sfr).
  *   1.16ac: Fix up SMP support somewhat. You can now force SMP on and we
  *	   make _all_ APM calls on the CPU#0. Fix unsafe sign bug.
@@ -260,12 +258,6 @@ extern int (*console_blank_hook)(int);
  *	    [no-]smp			Use apm even on an SMP box
  *	    bounce[-_]interval=<n>	number of ticks to ignore suspend
  *	    				bounces
- *          idle[-_]threshold=<n>       System idle percentage above which to
- *                                      make APM BIOS idle calls. Set it to
- *                                      100 to disable.
- *          idle[-_]period=<n>          Period (in 1/100s of a second) over
- *                                      which the idle percentage is
- *                                      calculated.
  */
 
 /* KNOWN PROBLEM MACHINES:
@@ -355,26 +347,12 @@ struct apm_user {
 #define APM_BIOS_MAGIC		0x4101
 
 /*
- * idle percentage above which bios idle calls are done
- */
-#ifdef CONFIG_APM_CPU_IDLE
-#define DEFAULT_IDLE_THRESHOLD	95
-#else
-#define DEFAULT_IDLE_THRESHOLD	100
-#endif
-#define DEFAULT_IDLE_PERIOD	(100 / 3)
-
-/*
  * Local variables
  */
 static struct {
 	unsigned long	offset;
 	unsigned short	segment;
 } apm_bios_entry;
-static int clock_slowed;
-static int idle_threshold __read_mostly = DEFAULT_IDLE_THRESHOLD;
-static int idle_period __read_mostly = DEFAULT_IDLE_PERIOD;
-static int set_pm_idle;
 static int suspends_pending;
 static int standbys_pending;
 static int ignore_sys_suspend;
@@ -804,165 +782,6 @@ static int set_system_power_state(u_short state)
 }
 
 /**
- *	apm_do_idle	-	perform power saving
- *
- *	This function notifies the BIOS that the processor is (in the view
- *	of the OS) idle. It returns -1 in the event that the BIOS refuses
- *	to handle the idle request. On a success the function returns 1
- *	if the BIOS did clock slowing or 0 otherwise.
- */
-
-static int apm_do_idle(void)
-{
-	u32 eax;
-	u8 ret = 0;
-	int idled = 0;
-	int polling;
-	int err = 0;
-
-	polling = !!(current_thread_info()->status & TS_POLLING);
-	if (polling) {
-		current_thread_info()->status &= ~TS_POLLING;
-		/*
-		 * TS_POLLING-cleared state must be visible before we
-		 * test NEED_RESCHED:
-		 */
-		smp_mb();
-	}
-	if (!need_resched()) {
-		idled = 1;
-		ret = apm_bios_call_simple(APM_FUNC_IDLE, 0, 0, &eax, &err);
-	}
-	if (polling)
-		current_thread_info()->status |= TS_POLLING;
-
-	if (!idled)
-		return 0;
-
-	if (ret) {
-		static unsigned long t;
-
-		/* This always fails on some SMP boards running UP kernels.
-		 * Only report the failure the first 5 times.
-		 */
-		if (++t < 5) {
-			printk(KERN_DEBUG "apm_do_idle failed (%d)\n", err);
-			t = jiffies;
-		}
-		return -1;
-	}
-	clock_slowed = (apm_info.bios.flags & APM_IDLE_SLOWS_CLOCK) != 0;
-	return clock_slowed;
-}
-
-/**
- *	apm_do_busy	-	inform the BIOS the CPU is busy
- *
- *	Request that the BIOS brings the CPU back to full performance.
- */
-
-static void apm_do_busy(void)
-{
-	u32 dummy;
-	int err;
-
-	if (clock_slowed || ALWAYS_CALL_BUSY) {
-		(void)apm_bios_call_simple(APM_FUNC_BUSY, 0, 0, &dummy, &err);
-		clock_slowed = 0;
-	}
-}
-
-/*
- * If no process has really been interested in
- * the CPU for some time, we want to call BIOS
- * power management - we probably want
- * to conserve power.
- */
-#define IDLE_CALC_LIMIT	(HZ * 100)
-#define IDLE_LEAKY_MAX	16
-
-static void (*original_pm_idle)(void) __read_mostly;
-
-/**
- * apm_cpu_idle		-	cpu idling for APM capable Linux
- *
- * This is the idling function the kernel executes when APM is available. It
- * tries to do BIOS powermanagement based on the average system idle time.
- * Furthermore it calls the system default idle routine.
- */
-
-static void apm_cpu_idle(void)
-{
-	static int use_apm_idle; /* = 0 */
-	static unsigned int last_jiffies; /* = 0 */
-	static unsigned int last_stime; /* = 0 */
-
-	int apm_idle_done = 0;
-	unsigned int jiffies_since_last_check = jiffies - last_jiffies;
-	unsigned int bucket;
-
-recalc:
-	if (jiffies_since_last_check > IDLE_CALC_LIMIT) {
-		use_apm_idle = 0;
-		last_jiffies = jiffies;
-		last_stime = current->stime;
-	} else if (jiffies_since_last_check > idle_period) {
-		unsigned int idle_percentage;
-
-		idle_percentage = current->stime - last_stime;
-		idle_percentage *= 100;
-		idle_percentage /= jiffies_since_last_check;
-		use_apm_idle = (idle_percentage > idle_threshold);
-		if (apm_info.forbid_idle)
-			use_apm_idle = 0;
-		last_jiffies = jiffies;
-		last_stime = current->stime;
-	}
-
-	bucket = IDLE_LEAKY_MAX;
-
-	while (!need_resched()) {
-		if (use_apm_idle) {
-			unsigned int t;
-
-			t = jiffies;
-			switch (apm_do_idle()) {
-			case 0:
-				apm_idle_done = 1;
-				if (t != jiffies) {
-					if (bucket) {
-						bucket = IDLE_LEAKY_MAX;
-						continue;
-					}
-				} else if (bucket) {
-					bucket--;
-					continue;
-				}
-				break;
-			case 1:
-				apm_idle_done = 1;
-				break;
-			default: /* BIOS refused */
-				break;
-			}
-		}
-		if (original_pm_idle)
-			original_pm_idle();
-		else
-			default_idle();
-		local_irq_disable();
-		jiffies_since_last_check = jiffies - last_jiffies;
-		if (jiffies_since_last_check > idle_period)
-			goto recalc;
-	}
-
-	if (apm_idle_done)
-		apm_do_busy();
-
-	local_irq_enable();
-}
-
-/**
  *	apm_power_off	-	ask the BIOS to power off
  *
  *	Handle the power off sequence. This is the one piece of code we
@@ -1869,12 +1688,6 @@ static int __init apm_setup(char *str)
 		if ((strncmp(str, "bounce-interval=", 16) == 0) ||
 		    (strncmp(str, "bounce_interval=", 16) == 0))
 			bounce_interval = simple_strtol(str + 16, NULL, 0);
-		if ((strncmp(str, "idle-threshold=", 15) == 0) ||
-		    (strncmp(str, "idle_threshold=", 15) == 0))
-			idle_threshold = simple_strtol(str + 15, NULL, 0);
-		if ((strncmp(str, "idle-period=", 12) == 0) ||
-		    (strncmp(str, "idle_period=", 12) == 0))
-			idle_period = simple_strtol(str + 12, NULL, 0);
 		invert = (strncmp(str, "no-", 3) == 0) ||
 			(strncmp(str, "no_", 3) == 0);
 		if (invert)
@@ -1886,7 +1699,6 @@ static int __init apm_setup(char *str)
 			power_off = !invert;
 		if (strncmp(str, "smp", 3) == 0) {
 			smp = !invert;
-			idle_threshold = 100;
 		}
 		if ((strncmp(str, "allow-ints", 10) == 0) ||
 		    (strncmp(str, "allow_ints", 10) == 0))
@@ -1987,17 +1799,6 @@ static int __init apm_is_horked_d850md(const struct dmi_system_id *d)
 	return 0;
 }
 
-/* Some APM bioses hang on APM idle calls */
-static int __init apm_likes_to_melt(const struct dmi_system_id *d)
-{
-	if (apm_info.forbid_idle == 0) {
-		apm_info.forbid_idle = 1;
-		printk(KERN_INFO "%s machine detected. "
-		       "Disabling APM idle calls.\n", d->ident);
-	}
-	return 0;
-}
-
 /*
  *  Check for clue free BIOS implementations who use
  *  the following QA technique
@@ -2138,16 +1939,6 @@ static struct dmi_system_id __initdata apm_dmi_table[] = {
 			DMI_MATCH(DMI_BIOS_VENDOR, "Phoenix Technologies LTD"),
 			DMI_MATCH(DMI_BIOS_VERSION, "A11"), },
 	},
-	{	/* APM idle hangs */
-		apm_likes_to_melt, "Jabil AMD",
-		{	DMI_MATCH(DMI_BIOS_VENDOR, "American Megatrends Inc."),
-			DMI_MATCH(DMI_BIOS_VERSION, "0AASNP06"), },
-	},
-	{	/* APM idle hangs */
-		apm_likes_to_melt, "AMI Bios",
-		{	DMI_MATCH(DMI_BIOS_VENDOR, "American Megatrends Inc."),
-			DMI_MATCH(DMI_BIOS_VERSION, "0AASNP05"), },
-	},
 	{	/* Handle problems with APM on Sony Vaio PCG-N505X(DE) */
 		swab_apm_power_in_minutes, "Sony VAIO",
 		{	DMI_MATCH(DMI_BIOS_VENDOR, "Phoenix Technologies LTD"),
@@ -2377,14 +2168,6 @@ static int __init apm_init(void)
 	if (misc_register(&apm_device))
 		printk(KERN_WARNING "apm: Could not register misc device.\n");
 
-	if (HZ != 100)
-		idle_period = (idle_period * HZ) / 100;
-	if (idle_threshold < 100) {
-		original_pm_idle = pm_idle;
-		pm_idle  = apm_cpu_idle;
-		set_pm_idle = 1;
-	}
-
 	return 0;
 }
 
@@ -2392,15 +2175,6 @@ static void __exit apm_exit(void)
 {
 	int error;
 
-	if (set_pm_idle) {
-		pm_idle = original_pm_idle;
-		/*
-		 * We are about to unload the current idle thread pm callback
-		 * (pm_idle), Wait for all processors to update cached/local
-		 * copies of pm_idle before proceeding.
-		 */
-		kick_all_cpus_sync();
-	}
 	if (((apm_info.bios.flags & APM_BIOS_DISENGAGED) == 0)
 	    && (apm_info.connection_version > 0x0100)) {
 		error = apm_engage_power_management(APM_DEVICE_ALL, 0);
@@ -2437,12 +2211,6 @@ MODULE_PARM_DESC(broken_psr, "BIOS has a broken GetPowerStatus call");
 module_param(realmode_power_off, bool, 0444);
 MODULE_PARM_DESC(realmode_power_off,
 		"Switch to real mode before powering off");
-module_param(idle_threshold, int, 0444);
-MODULE_PARM_DESC(idle_threshold,
-	"System idle percentage above which to make APM BIOS idle calls");
-module_param(idle_period, int, 0444);
-MODULE_PARM_DESC(idle_period,
-	"Period (in sec/100) over which to caculate the idle percentage");
 module_param(smp, bool, 0444);
 MODULE_PARM_DESC(smp,
 	"Set this to enable APM use on an SMP platform. Use with caution on older systems");
-- 
1.7.12.rc0

[PATCH 3/4] x86, idle: make default_idle() static

[Len Brown]

From: Len Brown <len.brown@intel.com>

default_idle() was public and exported to modules
for the benefit of APM.  But APM no longer touches
default_idle(), so default_idle() can now be private.

Cc: x86@kernel.org
Signed-off-by: Len Brown <len.brown@intel.com>
---
 arch/x86/include/asm/processor.h | 1 -
 arch/x86/kernel/process.c        | 5 +----
 2 files changed, 1 insertion(+), 5 deletions(-)

diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index 39bc577..b02e48c 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -979,7 +979,6 @@ extern bool cpu_has_amd_erratum(const int *);
 extern unsigned long arch_align_stack(unsigned long sp);
 extern void free_init_pages(char *what, unsigned long begin, unsigned long end);
 
-void default_idle(void);
 bool set_pm_idle_to_default(void);
 
 void stop_this_cpu(void *dummy);
diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
index 735279e..165f870 100644
--- a/arch/x86/kernel/process.c
+++ b/arch/x86/kernel/process.c
@@ -479,7 +479,7 @@ void cpu_idle(void)
  * We use this if we don't have any better
  * idle routine..
  */
-void default_idle(void)
+static void default_idle(void)
 {
 	if (hlt_use_halt()) {
 		trace_power_start_rcuidle(POWER_CSTATE, 1, smp_processor_id());
@@ -504,9 +504,6 @@ void default_idle(void)
 		cpu_relax();
 	}
 }
-#ifdef CONFIG_APM_MODULE
-EXPORT_SYMBOL(default_idle);
-#endif
 
 bool set_pm_idle_to_default(void)
 {
-- 
1.7.12.rc0

[PATCH 4/4] PM: cleanup: stop mandating that platforms export (pm_idle)()

[Len Brown]

From: Len Brown <len.brown@intel.com>

(pm_idle)() was originally used on x86 to vector bewteen
ACPI and APM.  With the advent of CPU_IDLE, that reason
for pm_idle to exist vanished.

But x86 APM still scribbled on pm_idle from a module,
so pm_idle didn't go away.  Worse, it was declared in pm.h,
and so it spread to other architectures as dead code.

But today, APM no longer scribbles on pm_idle, so
x86 no longer requires pm_idle to be visible to modules,
or global at all.

Here we remove pm_idle from pm.h, to stop the mandate
that all architectures define it.

This deletes dead code from most architectures,
while some continue using their own internal pm_idle.

At the end of the day, pm_idle...
becomes static in sh, was global
becomes static in x86, was EXPORT_SYMBOL
becomes as global in sparc, was EXPORT_SYMBOL
continues as static in m32r (no pm.h use there)
and is deleted from all other places in the kernel.

Signed-off-by: Len Brown <len.brown@intel.com>
Cc: x86@kernel.org # x86
Cc: Mike Frysinger <vapier@gentoo.org> # blackfin
Cc: Jonas Bonn <jonas@southpole.se> # openrisc
Cc: Tony Luck <tony.luck@intel.com> # ia64
Cc: David Howells <dhowells@redhat.com> # mn10300
Cc: Mikael Starvik <starvik@axis.com> # cris
Cc: Michal Simek <monstr@monstr.eu> # microblaze
Cc: Paul Mundt <lethal@linux-sh.org> # sh
Cc: David S. Miller <davem@davemloft.net> # sparc
Cc: Russell King <linux@arm.linux.org.uk> # ARM
Cc: Rafael J. Wysocki <rjw@sisk.pl> # PM
---
 arch/arm/kernel/process.c         | 12 +++---------
 arch/blackfin/kernel/process.c    |  9 +--------
 arch/cris/kernel/process.c        | 17 ++---------------
 arch/ia64/include/asm/processor.h |  2 --
 arch/ia64/kernel/process.c        | 10 ++--------
 arch/ia64/kernel/setup.c          |  1 -
 arch/microblaze/kernel/process.c  |  8 +-------
 arch/mn10300/kernel/process.c     | 16 ++--------------
 arch/openrisc/kernel/idle.c       |  5 -----
 arch/sh/kernel/idle.c             |  2 +-
 arch/sparc/include/asm/setup.h    |  1 +
 arch/sparc/kernel/process_32.c    |  1 -
 arch/unicore32/kernel/process.c   |  5 -----
 arch/x86/kernel/process.c         |  5 +----
 include/linux/pm.h                |  1 -
 kernel/smp.c                      |  4 ++--
 16 files changed, 16 insertions(+), 83 deletions(-)

diff --git a/arch/arm/kernel/process.c b/arch/arm/kernel/process.c
index 19c95ea..6af852e 100644
--- a/arch/arm/kernel/process.c
+++ b/arch/arm/kernel/process.c
@@ -172,14 +172,8 @@ static void default_idle(void)
 	local_irq_enable();
 }
 
-void (*pm_idle)(void) = default_idle;
-EXPORT_SYMBOL(pm_idle);
-
 /*
- * The idle thread, has rather strange semantics for calling pm_idle,
- * but this is what x86 does and we need to do the same, so that
- * things like cpuidle get called in the same way.  The only difference
- * is that we always respect 'hlt_counter' to prevent low power idle.
+ * Respect 'hlt_counter' to prevent low power idle.
  */
 void cpu_idle(void)
 {
@@ -210,10 +204,10 @@ void cpu_idle(void)
 			} else if (!need_resched()) {
 				stop_critical_timings();
 				if (cpuidle_idle_call())
-					pm_idle();
+					default_idle();
 				start_critical_timings();
 				/*
-				 * pm_idle functions must always
+				 * idle functions must always
 				 * return with IRQs enabled.
 				 */
 				WARN_ON(irqs_disabled());
diff --git a/arch/blackfin/kernel/process.c b/arch/blackfin/kernel/process.c
index 62bcea7..892402a 100644
--- a/arch/blackfin/kernel/process.c
+++ b/arch/blackfin/kernel/process.c
@@ -42,9 +42,6 @@ unsigned long l1_stack_len;
 /*
  * Powermanagement idle function, if any..
  */
-void (*pm_idle)(void) = NULL;
-EXPORT_SYMBOL(pm_idle);
-
 void (*pm_power_off)(void) = NULL;
 EXPORT_SYMBOL(pm_power_off);
 
@@ -81,18 +78,14 @@ void cpu_idle(void)
 {
 	/* endless idle loop with no priority at all */
 	while (1) {
-		void (*idle)(void) = pm_idle;
-
 #ifdef CONFIG_HOTPLUG_CPU
 		if (cpu_is_offline(smp_processor_id()))
 			cpu_die();
 #endif
-		if (!idle)
-			idle = default_idle;
 		tick_nohz_idle_enter();
 		rcu_idle_enter();
 		while (!need_resched())
-			idle();
+			default_idle();
 		rcu_idle_exit();
 		tick_nohz_idle_exit();
 		preempt_enable_no_resched();
diff --git a/arch/cris/kernel/process.c b/arch/cris/kernel/process.c
index 66fd017..ff20d39 100644
--- a/arch/cris/kernel/process.c
+++ b/arch/cris/kernel/process.c
@@ -54,12 +54,8 @@ void enable_hlt(void)
 EXPORT_SYMBOL(enable_hlt);
  
 /*
- * The following aren't currently used.
+ * The following is currently used.
  */
-void (*pm_idle)(void);
-
-extern void default_idle(void);
-
 void (*pm_power_off)(void);
 EXPORT_SYMBOL(pm_power_off);
 
@@ -75,16 +71,7 @@ void cpu_idle (void)
 	/* endless idle loop with no priority at all */
 	while (1) {
 		while (!need_resched()) {
-			void (*idle)(void);
-			/*
-			 * Mark this as an RCU critical section so that
-			 * synchronize_kernel() in the unload path waits
-			 * for our completion.
-			 */
-			idle = pm_idle;
-			if (!idle)
-				idle = default_idle;
-			idle();
+			default_idle();
 		}
 		schedule_preempt_disabled();
 	}
diff --git a/arch/ia64/include/asm/processor.h b/arch/ia64/include/asm/processor.h
index 832dd37..dea1ed3 100644
--- a/arch/ia64/include/asm/processor.h
+++ b/arch/ia64/include/asm/processor.h
@@ -717,8 +717,6 @@ extern unsigned long boot_option_idle_override;
 enum idle_boot_override {IDLE_NO_OVERRIDE=0, IDLE_HALT, IDLE_FORCE_MWAIT,
 			 IDLE_NOMWAIT, IDLE_POLL};
 
-void default_idle(void);
-
 #define ia64_platform_is(x) (strcmp(x, platform_name) == 0)
 
 #endif /* !__ASSEMBLY__ */
diff --git a/arch/ia64/kernel/process.c b/arch/ia64/kernel/process.c
index dd6fc14..e7c651c 100644
--- a/arch/ia64/kernel/process.c
+++ b/arch/ia64/kernel/process.c
@@ -56,8 +56,6 @@ void (*ia64_mark_idle)(int);
 
 unsigned long boot_option_idle_override = IDLE_NO_OVERRIDE;
 EXPORT_SYMBOL(boot_option_idle_override);
-void (*pm_idle) (void);
-EXPORT_SYMBOL(pm_idle);
 void (*pm_power_off) (void);
 EXPORT_SYMBOL(pm_power_off);
 
@@ -229,7 +227,7 @@ update_pal_halt_status(int status)
 /*
  * We use this if we don't have any better idle routine..
  */
-void
+static void
 default_idle (void)
 {
 	local_irq_enable();
@@ -291,7 +289,6 @@ cpu_idle (void)
 		}
 
 		if (!need_resched()) {
-			void (*idle)(void);
 #ifdef CONFIG_SMP
 			min_xtp();
 #endif
@@ -299,10 +296,7 @@ cpu_idle (void)
 			if (mark_idle)
 				(*mark_idle)(1);
 
-			idle = pm_idle;
-			if (!idle)
-				idle = default_idle;
-			(*idle)();
+			default_idle();
 			if (mark_idle)
 				(*mark_idle)(0);
 #ifdef CONFIG_SMP
diff --git a/arch/ia64/kernel/setup.c b/arch/ia64/kernel/setup.c
index aaefd9b..2029cc0 100644
--- a/arch/ia64/kernel/setup.c
+++ b/arch/ia64/kernel/setup.c
@@ -1051,7 +1051,6 @@ cpu_init (void)
 		max_num_phys_stacked = num_phys_stacked;
 	}
 	platform_cpu_init();
-	pm_idle = default_idle;
 }
 
 void __init
diff --git a/arch/microblaze/kernel/process.c b/arch/microblaze/kernel/process.c
index 1944e00..508d225 100644
--- a/arch/microblaze/kernel/process.c
+++ b/arch/microblaze/kernel/process.c
@@ -40,7 +40,6 @@ void show_regs(struct pt_regs *regs)
 				regs->msr, regs->ear, regs->esr, regs->fsr);
 }
 
-void (*pm_idle)(void);
 void (*pm_power_off)(void) = NULL;
 EXPORT_SYMBOL(pm_power_off);
 
@@ -97,15 +96,10 @@ void cpu_idle(void)
 
 	/* endless idle loop with no priority at all */
 	while (1) {
-		void (*idle)(void) = pm_idle;
-
-		if (!idle)
-			idle = default_idle;
-
 		tick_nohz_idle_enter();
 		rcu_idle_enter();
 		while (!need_resched())
-			idle();
+			default_idle();
 		rcu_idle_exit();
 		tick_nohz_idle_exit();
 
diff --git a/arch/mn10300/kernel/process.c b/arch/mn10300/kernel/process.c
index 7dab0cd..6312a31 100644
--- a/arch/mn10300/kernel/process.c
+++ b/arch/mn10300/kernel/process.c
@@ -36,12 +36,6 @@
 #include "internal.h"
 
 /*
- * power management idle function, if any..
- */
-void (*pm_idle)(void);
-EXPORT_SYMBOL(pm_idle);
-
-/*
  * return saved PC of a blocked thread.
  */
 unsigned long thread_saved_pc(struct task_struct *tsk)
@@ -108,18 +102,12 @@ void cpu_idle(void)
 	/* endless idle loop with no priority at all */
 	for (;;) {
 		while (!need_resched()) {
-			void (*idle)(void);
-
 			smp_rmb();
-			idle = pm_idle;
-			if (!idle) {
 #if defined(CONFIG_SMP) && !defined(CONFIG_HOTPLUG_CPU)
-				idle = poll_idle;
+			poll_idle();
 #else  /* CONFIG_SMP && !CONFIG_HOTPLUG_CPU */
-				idle = default_idle;
+			default_idle();
 #endif /* CONFIG_SMP && !CONFIG_HOTPLUG_CPU */
-			}
-			idle();
 		}
 
 		schedule_preempt_disabled();
diff --git a/arch/openrisc/kernel/idle.c b/arch/openrisc/kernel/idle.c
index 7d618fe..5e8a3b6 100644
--- a/arch/openrisc/kernel/idle.c
+++ b/arch/openrisc/kernel/idle.c
@@ -39,11 +39,6 @@
 
 void (*powersave) (void) = NULL;
 
-static inline void pm_idle(void)
-{
-	barrier();
-}
-
 void cpu_idle(void)
 {
 	set_thread_flag(TIF_POLLING_NRFLAG);
diff --git a/arch/sh/kernel/idle.c b/arch/sh/kernel/idle.c
index 0c91016..f063b92 100644
--- a/arch/sh/kernel/idle.c
+++ b/arch/sh/kernel/idle.c
@@ -22,7 +22,7 @@
 #include <asm/smp.h>
 #include <asm/bl_bit.h>
 
-void (*pm_idle)(void);
+static void (*pm_idle)(void);
 
 static int hlt_counter;
 
diff --git a/arch/sparc/include/asm/setup.h b/arch/sparc/include/asm/setup.h
index 8a83699..33bef87 100644
--- a/arch/sparc/include/asm/setup.h
+++ b/arch/sparc/include/asm/setup.h
@@ -34,6 +34,7 @@ extern void sun_do_break(void);
 extern int stop_a_enabled;
 extern int scons_pwroff;
 
+extern void (*pm_idle)(void);
 #endif /* __KERNEL__ */
 
 #endif /* _SPARC_SETUP_H */
diff --git a/arch/sparc/kernel/process_32.c b/arch/sparc/kernel/process_32.c
index cb36e82..1c702bd 100644
--- a/arch/sparc/kernel/process_32.c
+++ b/arch/sparc/kernel/process_32.c
@@ -44,7 +44,6 @@
  * Set in pm platform drivers (apc.c and pmc.c)
  */
 void (*pm_idle)(void);
-EXPORT_SYMBOL(pm_idle);
 
 /* 
  * Power-off handler instantiation for pm.h compliance
diff --git a/arch/unicore32/kernel/process.c b/arch/unicore32/kernel/process.c
index b6f0458..3841ef97 100644
--- a/arch/unicore32/kernel/process.c
+++ b/arch/unicore32/kernel/process.c
@@ -45,11 +45,6 @@ static const char * const processor_modes[] = {
 	"UK18", "UK19", "UK1A", "EXTN", "UK1C", "UK1D", "UK1E", "SUSR"
 };
 
-/*
- * The idle thread, has rather strange semantics for calling pm_idle,
- * but this is what x86 does and we need to do the same, so that
- * things like cpuidle get called in the same way.
- */
 void cpu_idle(void)
 {
 	/* endless idle loop with no priority at all */
diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
index 165f870..c385cfa 100644
--- a/arch/x86/kernel/process.c
+++ b/arch/x86/kernel/process.c
@@ -372,10 +372,7 @@ EXPORT_SYMBOL(boot_option_idle_override);
 /*
  * Powermanagement idle function, if any..
  */
-void (*pm_idle)(void);
-#ifdef CONFIG_APM_MODULE
-EXPORT_SYMBOL(pm_idle);
-#endif
+static void (*pm_idle)(void);
 
 static inline int hlt_use_halt(void)
 {
diff --git a/include/linux/pm.h b/include/linux/pm.h
index f067e60..6b92c37 100644
--- a/include/linux/pm.h
+++ b/include/linux/pm.h
@@ -31,7 +31,6 @@
 /*
  * Callbacks for platform drivers to implement.
  */
-extern void (*pm_idle)(void);
 extern void (*pm_power_off)(void);
 extern void (*pm_power_off_prepare)(void);
 
diff --git a/kernel/smp.c b/kernel/smp.c
index d0ae5b2..ede77e4 100644
--- a/kernel/smp.c
+++ b/kernel/smp.c
@@ -803,11 +803,11 @@ static void do_nothing(void *unused)
 /**
  * kick_all_cpus_sync - Force all cpus out of idle
  *
- * Used to synchronize the update of pm_idle function pointer. It's
+ * Used to synchronize the update of idle function pointer. It's
  * called after the pointer is updated and returns after the dummy
  * callback function has been executed on all cpus. The execution of
  * the function can only happen on the remote cpus after they have
- * left the idle function which had been called via pm_idle function
+ * left the idle function which had been called via idle function
  * pointer. So it's guaranteed that nothing uses the previous pointer
  * anymore.
  */
-- 
1.7.12.rc0

Re: [PATCH 2/4] x86 idle APM: delete apm_cpu_idle()

[Alan Cox]

On Fri, 27 Jul 2012 18:42:53 -0400
Len Brown <lenb@kernel.org> wrote:

> From: Len Brown <len.brown@intel.com>
> 
> The APM idle feature to call into the BIOS
> is known to break some machines, and it has dubious benefit
> on the (decades old) machines it doesn't break.

You mean "doesn't fit my current plan" I think. I see almost no bugzilla
APM reports. It's been solid for years.

It makes a big difference on older systems as it drops the clock. If we
are going to drop this we should probaly also drop APM support entirely
and 386/486 support.

If not IMHO it should stay. Various embedded platforms are still using
ancient hardware setups.

This is a small stable piece of code that has required no maintainance in
years

Furthermore we have a feature removal process. Mark it down to be removed
in July 2013 if there are no objections, and then wait as per proper
process.

NAK

Alan

Re: [PATCH 2/4] x86 idle APM: delete apm_cpu_idle()

[Alan Cox]

On Fri, 27 Jul 2012 18:42:53 -0400
Len Brown <lenb@kernel.org> wrote:

> From: Len Brown <len.brown@intel.com>
> 
> The APM idle feature to call into the BIOS
> is known to break some machines, and it has dubious benefit
> on the (decades old) machines it doesn't break.

You mean "doesn't fit my current plan" I think. I see almost no bugzilla
APM reports. It's been solid for years.

It makes a big difference on older systems as it drops the clock. If we
are going to drop this we should probaly also drop APM support entirely
and 386/486 support.

If not IMHO it should stay. Various embedded platforms are still using
ancient hardware setups.

This is a small stable piece of code that has required no maintainance in
years

Furthermore we have a feature removal process. Mark it down to be removed
in July 2013 if there are no objections, and then wait as per proper
process.

NAK

Alan

Re: [PATCH 2/4] x86 idle APM: delete apm_cpu_idle()

[Len Brown]

On 07/28/2012 06:11 AM, Alan Cox wrote:
> On Fri, 27 Jul 2012 18:42:53 -0400
> Len Brown <lenb@kernel.org> wrote:
> 
>> From: Len Brown <len.brown@intel.com>
>>
>> The APM idle feature to call into the BIOS
>> is known to break some machines, and it has dubious benefit
>> on the (decades old) machines it doesn't break.
> 
> You mean "doesn't fit my current plan" I think. I see almost no bugzilla
> APM reports. It's been solid for years.


Hm, I thought it was actually you that mentioned that this particular
feature of APM caused some systems to fail...

Unfortunately quiet bugzilla doesn't tell us the difference between
"solid as a rock and used by millions of users every day"
and "nobody anywhere running new software on this old hardware".

> It makes a big difference on older systems as it drops the clock. If we
> are going to drop this we should probaly also drop APM support entirely
> and 386/486 support.

Do you have an APM system that boots a 2012 kernel?
Are you willing to test new kernels on it?

> If not IMHO it should stay. Various embedded platforms are still using
> ancient hardware setups.
> 
> This is a small stable piece of code that has required no maintainance in
> years
> 
> Furthermore we have a feature removal process. Mark it down to be removed
> in July 2013 if there are no objections, and then wait as per proper
> process.
> 
> NAK

At your request 16 months ago, we did exactly that.
Further, we added build-time and run-time warnings and all they did
was cause distro mis-merges and requests to remove the warnings.

16 months ago we came within inches of dropping APM entirely,
as Stephen said he hadn't maintained it for a long time.
Jiri volunteered to look after it, and Pavel offered
that he had 1 surviving machine someplace that actually
supports APM, though I don't know if boots.

I don't dispute that there may be some APM systems running someplace,
but if nobody is going to test a 2012 kernel on such hardware,
then we are kidding ourselves if we say we "support" today's kernel on it.
Also, the whole idea was even if we do support such HW, this patch
is supposed to make that HW more stable, not less stable.

-Len

Re: [PATCH 2/4] x86 idle APM: delete apm_cpu_idle()

[Len Brown]

On 07/28/2012 06:11 AM, Alan Cox wrote:
> On Fri, 27 Jul 2012 18:42:53 -0400
> Len Brown <lenb@kernel.org> wrote:
> 
>> From: Len Brown <len.brown@intel.com>
>>
>> The APM idle feature to call into the BIOS
>> is known to break some machines, and it has dubious benefit
>> on the (decades old) machines it doesn't break.
> 
> You mean "doesn't fit my current plan" I think. I see almost no bugzilla
> APM reports. It's been solid for years.


Hm, I thought it was actually you that mentioned that this particular
feature of APM caused some systems to fail...

Unfortunately quiet bugzilla doesn't tell us the difference between
"solid as a rock and used by millions of users every day"
and "nobody anywhere running new software on this old hardware".

> It makes a big difference on older systems as it drops the clock. If we
> are going to drop this we should probaly also drop APM support entirely
> and 386/486 support.

Do you have an APM system that boots a 2012 kernel?
Are you willing to test new kernels on it?

> If not IMHO it should stay. Various embedded platforms are still using
> ancient hardware setups.
> 
> This is a small stable piece of code that has required no maintainance in
> years
> 
> Furthermore we have a feature removal process. Mark it down to be removed
> in July 2013 if there are no objections, and then wait as per proper
> process.
> 
> NAK

At your request 16 months ago, we did exactly that.
Further, we added build-time and run-time warnings and all they did
was cause distro mis-merges and requests to remove the warnings.

16 months ago we came within inches of dropping APM entirely,
as Stephen said he hadn't maintained it for a long time.
Jiri volunteered to look after it, and Pavel offered
that he had 1 surviving machine someplace that actually
supports APM, though I don't know if boots.

I don't dispute that there may be some APM systems running someplace,
but if nobody is going to test a 2012 kernel on such hardware,
then we are kidding ourselves if we say we "support" today's kernel on it.
Also, the whole idea was even if we do support such HW, this patch
is supposed to make that HW more stable, not less stable.

-Len

Re: [linux-pm] [PATCH 4/4] PM: cleanup: stop mandating that platforms export (pm_idle)()

[Kevin Hilman]

+ linux-arm-kernel

Len Brown <lenb@kernel.org> writes:

> From: Len Brown <len.brown@intel.com>
>
> (pm_idle)() was originally used on x86 to vector bewteen
> ACPI and APM.  With the advent of CPU_IDLE, that reason
> for pm_idle to exist vanished.
>
> But x86 APM still scribbled on pm_idle from a module,
> so pm_idle didn't go away.  Worse, it was declared in pm.h,
> and so it spread to other architectures as dead code.
>
> But today, APM no longer scribbles on pm_idle, so
> x86 no longer requires pm_idle to be visible to modules,
> or global at all.
>
> Here we remove pm_idle from pm.h, to stop the mandate
> that all architectures define it.
>
> This deletes dead code from most architectures,
> while some continue using their own internal pm_idle.
>
> At the end of the day, pm_idle...
> becomes static in sh, was global
> becomes static in x86, was EXPORT_SYMBOL
> becomes as global in sparc, was EXPORT_SYMBOL
> continues as static in m32r (no pm.h use there)
> and is deleted from all other places in the kernel.
>
> Signed-off-by: Len Brown <len.brown@intel.com>
> Cc: x86@kernel.org # x86
> Cc: Mike Frysinger <vapier@gentoo.org> # blackfin
> Cc: Jonas Bonn <jonas@southpole.se> # openrisc
> Cc: Tony Luck <tony.luck@intel.com> # ia64
> Cc: David Howells <dhowells@redhat.com> # mn10300
> Cc: Mikael Starvik <starvik@axis.com> # cris
> Cc: Michal Simek <monstr@monstr.eu> # microblaze
> Cc: Paul Mundt <lethal@linux-sh.org> # sh
> Cc: David S. Miller <davem@davemloft.net> # sparc
> Cc: Russell King <linux@arm.linux.org.uk> # ARM
> Cc: Rafael J. Wysocki <rjw@sisk.pl> # PM
> ---
>  arch/arm/kernel/process.c         | 12 +++---------

Just looking at the ARM changes, it looks good to me.  I tested it with
and without CPUidle on my ARM-based TI/OMAP platforms (3430/n900,
4430/Panda)

So for the arch/arm changes:

Reviewed-by: Kevin Hilman <khilman@ti.com>
Tested-by: Kevin Hilman <khilman@ti.com>

Kevin

[linux-pm] [PATCH 4/4] PM: cleanup: stop mandating that platforms export (pm_idle)()

[Kevin Hilman]

+ linux-arm-kernel

Len Brown <lenb@kernel.org> writes:

> From: Len Brown <len.brown@intel.com>
>
> (pm_idle)() was originally used on x86 to vector bewteen
> ACPI and APM.  With the advent of CPU_IDLE, that reason
> for pm_idle to exist vanished.
>
> But x86 APM still scribbled on pm_idle from a module,
> so pm_idle didn't go away.  Worse, it was declared in pm.h,
> and so it spread to other architectures as dead code.
>
> But today, APM no longer scribbles on pm_idle, so
> x86 no longer requires pm_idle to be visible to modules,
> or global at all.
>
> Here we remove pm_idle from pm.h, to stop the mandate
> that all architectures define it.
>
> This deletes dead code from most architectures,
> while some continue using their own internal pm_idle.
>
> At the end of the day, pm_idle...
> becomes static in sh, was global
> becomes static in x86, was EXPORT_SYMBOL
> becomes as global in sparc, was EXPORT_SYMBOL
> continues as static in m32r (no pm.h use there)
> and is deleted from all other places in the kernel.
>
> Signed-off-by: Len Brown <len.brown@intel.com>
> Cc: x86 at kernel.org # x86
> Cc: Mike Frysinger <vapier@gentoo.org> # blackfin
> Cc: Jonas Bonn <jonas@southpole.se> # openrisc
> Cc: Tony Luck <tony.luck@intel.com> # ia64
> Cc: David Howells <dhowells@redhat.com> # mn10300
> Cc: Mikael Starvik <starvik@axis.com> # cris
> Cc: Michal Simek <monstr@monstr.eu> # microblaze
> Cc: Paul Mundt <lethal@linux-sh.org> # sh
> Cc: David S. Miller <davem@davemloft.net> # sparc
> Cc: Russell King <linux@arm.linux.org.uk> # ARM
> Cc: Rafael J. Wysocki <rjw@sisk.pl> # PM
> ---
>  arch/arm/kernel/process.c         | 12 +++---------

Just looking at the ARM changes, it looks good to me.  I tested it with
and without CPUidle on my ARM-based TI/OMAP platforms (3430/n900,
4430/Panda)

So for the arch/arm changes:

Reviewed-by: Kevin Hilman <khilman@ti.com>
Tested-by: Kevin Hilman <khilman@ti.com>

Kevin