[PATCH] Oops and panic while unloading holder of pm_idle

From: BlaisorBlade
Date: Fri Aug 20 2004 - 05:18:05 EST

(CC me on replies as I'm not subscribed).

A short description, with my hypothesis about how the panic() happened:

My 2.6.7 preemptible kernel oopsed because when I unloaded the "processor"
module (driver/acpi/processor.c), the pm_idle(see arch/i386/kernel/process.c)
function he provided was called after the module being unloaded (notice that
the "processor" module is not listed below).

I.e., cpu_idle did "idle = pm_idle", it was probably preempted (I run with
CONFIG_PREEMPT=y), the processor module was unloaded, and then it called
"(*idle)();". In fact it does not happen always (I just got again this panic
by unloading the same module, and checked that the address was from the
"processor", but I cannot get it again; don't ask me why it can be obtained
only the first time it is unloaded, but not after reloading and re-unloading
it).

This could happen as well on SMP, so we need a spinlock for accessing
pm_idle. We could maybe as well use a semaphore (since we will always be in
process context), but IMHO there is too much overhead. And it does not make
sense for the idle thread to sleep while holding a semaphore (I don't know if
it's a bug). So I attach spinlock-protect-pm_idle.patch (which corrects some
more things on some archs). With this patch applied, I cannot reproduce the
problem any more.

But that does not suffice: saying

static void (*pm_idle_save)(void);
pm_idle_save = pm_idle;
pm_idle = my_own_pm_idle;

does not work if you stack more modules onto it. Say, if module1 and module2
both install their pm_idle and then I unload module1 and after I unload
module2: module2 will restore module1_pm_idle, so we get Oopses. I.e. we need
a stack of pm_idle functions + some register_pm_idle() APIs. Do you agree?

This may be a bit overkill given that only APM and ACPI, and, on SPARC,
arch/sparc/kernel/{apc,pmc}.c, define their pm_idle function. So, as an
alternative, see this code (which assumes pm_idle is renamed to _pm_idle and
unexported, to force changes in all drivers):

int install_pm_idle(void (*idle)(void))
{
if (_pm_idle == NULL) {
_pm_idle = idle;
return 1;
} else
return 0;
}
EXPORT_SYMBOL(install_pm_idle);

Also, in my case, I don't think we have this kind of panic, because pm_idle is
just defined by APM and ACPI (CONFIG_APM=y, and APM is not supported by my
laptop). I also checked, when getting again the same panic, that the faulty
EIP was actually inside the processor module (from /proc/modules).

And also, it PANICKED, but CONTINUED TO RUN: notice the last 3 lines:
<0>Kernel panic: Attempted to kill the idle task!
In idle task - not syncing
<6>ACPI: Processor [CPU0] (supports C1 C2)
The third one comes from reloading the "processor" module.

For reference, I attach the Oops output and the cpu_idle disassemble, so that
you can check the EIP value. However I checked that it was actually calling
pm_idle.

Unable to handle kernel paging request at virtual address e0e8a238
printing eip:
e0e8a238
*pde = 1e1e1067
*pte = 00000000
Oops: 0000 [#1]
PREEMPT
Modules linked in: fan button battery non_fatal ac binfmt_misc snd_seq_oss
snd_seq_midi_event snd_seq snd_pcm_oss snd_mixer_oss snd_intel8x0
snd_ac97_codec snd_pcm snd_timer snd_page_alloc gameport snd_mpu401_uart
snd_rawmidi snd_seq_device snd soundcore af_packet ipv6 ds yenta_socket
pcmcia_core eth1394 tg3 ohci1394 ieee1394 nls_iso8859_15 nls_cp850 vfat fat
psmouse amd64_agp agpgart ide_cd cdrom sd_mod usb_storage scsi_mod tsdev
evdev dm_mod usbhid usbmouse ehci_hcd ohci_hcd usbcore rtc
CPU: 0
EIP: 0060:[<e0e8a238>] Not tainted
EFLAGS: 00010212 (2.6.7)
EIP is at 0xe0e8a238
eax: 00f6b2a4 ebx: 00008008 ecx: 00f6a78f edx: 00008008
esi: c15666b0 edi: c03d41c0 ebp: c1566600 esp: c03adfc8
ds: 007b es: 007b ss: 0068
Process swapper (pid: 0, threadinfo=c03ac000 task=c0330a40)
Stack: 00099100 00099100 c03ac000 00099100 c03d41c0 00426007 c01020cd c03ac000
c03ae61d 00000012 c03ae370 c03d3fc0 00000800 c010019f
Call Trace:
[<c01020cd>] cpu_idle+0x2d/0x40
[<c03ae61d>] start_kernel+0x14d/0x170
[<c03ae370>] unknown_bootoption+0x0/0x120

Code: Bad EIP value.
<0>Kernel panic: Attempted to kill the idle task!
In idle task - not syncing
<6>ACPI: Processor [CPU0] (supports C1 C2)

(gdb) disassemble cpu_idle
Dump of assembler code for function cpu_idle:
0xc01020a0 <cpu_idle+0>: push %ebx
0xc01020a1 <cpu_idle+1>: mov $0xffffe000,%ebx
0xc01020a6 <cpu_idle+6>: and %esp,%ebx
0xc01020a8 <cpu_idle+8>: jmp 0xc01020cd <cpu_idle+45>
0xc01020aa <cpu_idle+10>: lea 0x0(%esi),%esi
0xc01020b0 <cpu_idle+16>: mov 0xc03d3504,%eax
0xc01020b5 <cpu_idle+21>: mov $0xc0102030,%edx
0xc01020ba <cpu_idle+26>: test %eax,%eax
0xc01020bc <cpu_idle+28>: cmove %edx,%eax
0xc01020bf <cpu_idle+31>: mov 0xc0331e40,%edx
0xc01020c5 <cpu_idle+37>: mov %edx,0xc03e8e84
0xc01020cb <cpu_idle+43>: call *%eax
0xc01020cd <cpu_idle+45>: mov 0x8(%ebx),%eax
0xc01020d0 <cpu_idle+48>: test $0x8,%al
0xc01020d2 <cpu_idle+50>: je 0xc01020b0 <cpu_idle+16>
0xc01020d4 <cpu_idle+52>: call 0xc02d9200 <schedule>
0xc01020d9 <cpu_idle+57>: jmp 0xc01020cd <cpu_idle+45>
0xc01020db <cpu_idle+59>: nop
0xc01020dc <cpu_idle+60>: lea 0x0(%esi,1),%esi

--
Paolo Giarrusso, aka Blaisorblade
Linux registered user n. 292729










Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade_spam@xxxxxxxx>
---

vanilla-linux-2.6.7-SKAS-paolo/arch/arm/kernel/process.c | 9 +++++-
vanilla-linux-2.6.7-SKAS-paolo/arch/arm26/kernel/armksyms.c | 1
vanilla-linux-2.6.7-SKAS-paolo/arch/arm26/kernel/process.c | 7 ++++-
vanilla-linux-2.6.7-SKAS-paolo/arch/cris/kernel/crisksyms.c | 2 +
vanilla-linux-2.6.7-SKAS-paolo/arch/cris/kernel/process.c | 7 ++++-
vanilla-linux-2.6.7-SKAS-paolo/arch/i386/kernel/apm.c | 4 ++
vanilla-linux-2.6.7-SKAS-paolo/arch/i386/kernel/i386_ksyms.c | 1
vanilla-linux-2.6.7-SKAS-paolo/arch/i386/kernel/process.c | 7 ++++-
vanilla-linux-2.6.7-SKAS-paolo/arch/ia64/kernel/acpi.c | 2 +
vanilla-linux-2.6.7-SKAS-paolo/arch/ia64/kernel/process.c | 5 ++-
vanilla-linux-2.6.7-SKAS-paolo/arch/sparc/kernel/apc.c | 5 ++-
vanilla-linux-2.6.7-SKAS-paolo/arch/sparc/kernel/pmc.c | 2 +
vanilla-linux-2.6.7-SKAS-paolo/arch/sparc/kernel/process.c | 9 +++++-
vanilla-linux-2.6.7-SKAS-paolo/arch/sparc/kernel/sparc_ksyms.c | 1
vanilla-linux-2.6.7-SKAS-paolo/arch/x86_64/kernel/process.c | 13 ++++++---
vanilla-linux-2.6.7-SKAS-paolo/arch/x86_64/kernel/x8664_ksyms.c | 1
vanilla-linux-2.6.7-SKAS-paolo/drivers/acpi/processor.c | 7 ++++-
vanilla-linux-2.6.7-SKAS-paolo/include/linux/pm.h | 14 ++++++++++
18 files changed, 84 insertions(+), 13 deletions(-)

diff -puN arch/arm/kernel/process.c~spinlock-protect-pm_idle arch/arm/kernel/process.c
--- vanilla-linux-2.6.7-SKAS/arch/arm/kernel/process.c~spinlock-protect-pm_idle 2004-08-17 20:21:20.000000000 +0200
+++ vanilla-linux-2.6.7-SKAS-paolo/arch/arm/kernel/process.c 2004-08-18 21:12:23.113797464 +0200
@@ -26,6 +26,7 @@
#include <linux/interrupt.h>
#include <linux/kallsyms.h>
#include <linux/init.h>
+#include <linux/pm.h>

#include <asm/system.h>
#include <asm/io.h>
@@ -78,6 +79,9 @@ EXPORT_SYMBOL(pm_idle);
void (*pm_power_off)(void);
EXPORT_SYMBOL(pm_power_off);

+spinlock_t pm_idle_lock = SPIN_LOCK_UNLOCKED;
+EXPORT_SYMBOL(pm_idle_lock);
+
/*
* This is our default idle handler. We need to disable
* interrupts here to ensure we don't miss a wakeup call.
@@ -99,7 +103,9 @@ void cpu_idle(void)
{
/* endless idle loop with no priority at all */
while (1) {
- void (*idle)(void) = pm_idle;
+ void (*idle)(void);
+ lock_pm_idle();
+ idle = pm_idle;
if (!idle)
idle = default_idle;
preempt_disable();
@@ -108,6 +114,7 @@ void cpu_idle(void)
idle();
leds_event(led_idle_end);
preempt_enable();
+ unlock_pm_idle();
schedule();
}
}
diff -puN arch/i386/kernel/process.c~spinlock-protect-pm_idle arch/i386/kernel/process.c
--- vanilla-linux-2.6.7-SKAS/arch/i386/kernel/process.c~spinlock-protect-pm_idle 2004-08-17 20:21:20.000000000 +0200
+++ vanilla-linux-2.6.7-SKAS-paolo/arch/i386/kernel/process.c 2004-08-17 21:04:06.000000000 +0200
@@ -36,6 +36,7 @@
#include <linux/module.h>
#include <linux/kallsyms.h>
#include <linux/ptrace.h>
+#include <linux/pm.h>

#include <asm/uaccess.h>
#include <asm/pgtable.h>
@@ -69,6 +70,7 @@ unsigned long thread_saved_pc(struct tas
* Powermanagement idle function, if any..
*/
void (*pm_idle)(void);
+spinlock_t pm_idle_lock = SPIN_LOCK_UNLOCKED;

void disable_hlt(void)
{
@@ -142,13 +144,16 @@ void cpu_idle (void)
/* endless idle loop with no priority at all */
while (1) {
while (!need_resched()) {
- void (*idle)(void) = pm_idle;
+ void (*idle)(void);
+ lock_pm_idle();
+ idle = pm_idle;

if (!idle)
idle = default_idle;

irq_stat[smp_processor_id()].idle_timestamp = jiffies;
idle();
+ unlock_pm_idle();
}
schedule();
}
diff -puN arch/cris/kernel/process.c~spinlock-protect-pm_idle arch/cris/kernel/process.c
--- vanilla-linux-2.6.7-SKAS/arch/cris/kernel/process.c~spinlock-protect-pm_idle 2004-08-17 20:21:20.000000000 +0200
+++ vanilla-linux-2.6.7-SKAS-paolo/arch/cris/kernel/process.c 2004-08-17 21:06:28.000000000 +0200
@@ -112,6 +112,7 @@
#include <linux/fs.h>
#include <linux/user.h>
#include <linux/elfcore.h>
+#include <linux/pm.h>

//#define DEBUG

@@ -179,6 +180,7 @@ EXPORT_SYMBOL(enable_hlt);
* The following aren't currently used.
*/
void (*pm_idle)(void);
+spinlock_t pm_idle_lock = SPIN_LOCK_UNLOCKED;

extern void default_idle(void);

@@ -193,12 +195,15 @@ void cpu_idle (void)
/* endless idle loop with no priority at all */
while (1) {
while (!need_resched()) {
- void (*idle)(void) = pm_idle;
+ void (*idle)(void);
+ lock_pm_idle();
+ idle = pm_idle;

if (!idle)
idle = default_idle;

idle();
+ unlock_pm_idle();
}
schedule();
}
diff -puN arch/ia64/kernel/process.c~spinlock-protect-pm_idle arch/ia64/kernel/process.c
--- vanilla-linux-2.6.7-SKAS/arch/ia64/kernel/process.c~spinlock-protect-pm_idle 2004-08-17 20:21:20.000000000 +0200
+++ vanilla-linux-2.6.7-SKAS-paolo/arch/ia64/kernel/process.c 2004-08-17 20:57:07.000000000 +0200
@@ -228,7 +228,9 @@ cpu_idle (void *unused)

/* endless idle loop with no priority at all */
while (1) {
- void (*idle)(void) = pm_idle;
+ void (*idle)(void);
+ lock_pm_idle();
+ idle = pm_idle;
if (!idle)
idle = default_idle;

@@ -241,6 +243,7 @@ cpu_idle (void *unused)
(*mark_idle)(1);
(*idle)();
}
+ unlock_pm_idle();

if (mark_idle)
(*mark_idle)(0);
diff -puN arch/arm26/kernel/process.c~spinlock-protect-pm_idle arch/arm26/kernel/process.c
--- vanilla-linux-2.6.7-SKAS/arch/arm26/kernel/process.c~spinlock-protect-pm_idle 2004-08-17 20:21:20.000000000 +0200
+++ vanilla-linux-2.6.7-SKAS-paolo/arch/arm26/kernel/process.c 2004-08-17 21:04:06.000000000 +0200
@@ -26,6 +26,7 @@
#include <linux/reboot.h>
#include <linux/interrupt.h>
#include <linux/init.h>
+#include <linux/pm.h>

#include <asm/system.h>
#include <asm/io.h>
@@ -72,6 +73,7 @@ __setup("hlt", hlt_setup);
*/
void (*pm_idle)(void);
void (*pm_power_off)(void);
+spinlock_t pm_idle_lock = SPIN_LOCK_UNLOCKED;

/*
* This is our default idle handler. We need to disable
@@ -94,12 +96,15 @@ void cpu_idle(void)
/* endless idle loop with no priority at all */
preempt_disable();
while (1) {
- void (*idle)(void) = pm_idle;
+ void (*idle)(void);
+ lock_pm_idle();
+ idle = pm_idle;
if (!idle)
idle = default_idle;
leds_event(led_idle_start);
while (!need_resched())
idle();
+ unlock_pm_idle();
leds_event(led_idle_end);
schedule();
}
diff -puN arch/sparc/kernel/process.c~spinlock-protect-pm_idle arch/sparc/kernel/process.c
--- vanilla-linux-2.6.7-SKAS/arch/sparc/kernel/process.c~spinlock-protect-pm_idle 2004-08-17 20:21:20.000000000 +0200
+++ vanilla-linux-2.6.7-SKAS-paolo/arch/sparc/kernel/process.c 2004-08-17 21:04:06.000000000 +0200
@@ -48,6 +48,7 @@
* Set in pm platform drivers
*/
void (*pm_idle)(void);
+spinlock_t pm_idle_lock = SPIN_LOCK_UNLOCKED;

/*
* Power-off handler instantiation for pm.h compliance
@@ -90,6 +91,7 @@ int cpu_idle(void)

/* endless idle loop with no priority at all */
for (;;) {
+ void (*idle)(void);
if (ARCH_SUN4C_SUN4) {
static int count = HZ;
static unsigned long last_jiffies;
@@ -121,9 +123,12 @@ int cpu_idle(void)
local_irq_restore(flags);
}

- while((!need_resched()) && pm_idle) {
- (*pm_idle)(); /* XXX Huh? On sparc?! */
+ lock_pm_idle();
+ idle = pm_idle;
+ while((!need_resched()) && idle) {
+ (*idle)(); /* XXX Huh? On sparc?! */
}
+ unlock_pm_idle();

schedule();
check_pgt_cache();
diff -puN arch/x86_64/kernel/process.c~spinlock-protect-pm_idle arch/x86_64/kernel/process.c
--- vanilla-linux-2.6.7-SKAS/arch/x86_64/kernel/process.c~spinlock-protect-pm_idle 2004-08-17 20:21:20.000000000 +0200
+++ vanilla-linux-2.6.7-SKAS-paolo/arch/x86_64/kernel/process.c 2004-08-17 21:04:06.000000000 +0200
@@ -33,6 +33,7 @@
#include <linux/irq.h>
#include <linux/ptrace.h>
#include <linux/version.h>
+#include <linux/pm.h>

#include <asm/uaccess.h>
#include <asm/pgtable.h>
@@ -58,6 +59,7 @@ atomic_t hlt_counter = ATOMIC_INIT(0);
* Powermanagement idle function, if any..
*/
void (*pm_idle)(void);
+spinlock_t pm_idle_lock = SPIN_LOCK_UNLOCKED;

void disable_hlt(void)
{
@@ -130,11 +132,14 @@ void cpu_idle (void)
{
/* endless idle loop with no priority at all */
while (1) {
- void (*idle)(void) = pm_idle;
+ void (*idle)(void);
+ lock_pm_idle();
+ idle = pm_idle;
if (!idle)
idle = default_idle;
while (!need_resched())
idle();
+ unlock_pm_idle();
schedule();
}
}
@@ -170,8 +175,9 @@ void __init select_idle_routine(const st
* Skip, if setup has overridden idle.
* Also, take care of system with asymmetric CPUs.
* Use, mwait_idle only if all cpus support it.
- * If not, we fallback to default_idle()
+ * If not, we fallback to default_idle() in cpu_idle().
*/
+ lock_pm_idle();
if (!pm_idle) {
if (!printed) {
printk("using mwait in idle threads.\n");
@@ -179,10 +185,9 @@ void __init select_idle_routine(const st
}
pm_idle = mwait_idle;
}
+ unlock_pm_idle();
return;
}
- pm_idle = default_idle;
- return;
}

static int __init idle_setup (char *str)
diff -puN arch/ia64/kernel/acpi.c~spinlock-protect-pm_idle arch/ia64/kernel/acpi.c
--- vanilla-linux-2.6.7-SKAS/arch/ia64/kernel/acpi.c~spinlock-protect-pm_idle 2004-08-17 20:21:20.000000000 +0200
+++ vanilla-linux-2.6.7-SKAS-paolo/arch/ia64/kernel/acpi.c 2004-08-17 20:35:54.000000000 +0200
@@ -61,6 +61,8 @@
void (*pm_idle) (void);
EXPORT_SYMBOL(pm_idle);
void (*pm_power_off) (void);
+spinlock_t pm_idle_lock = SPIN_LOCK_UNLOCKED;
+EXPORT_SYMBOL(pm_idle_lock);

unsigned char acpi_kbd_controller_present = 1;
unsigned char acpi_legacy_devices;
diff -puN arch/i386/kernel/apm.c~spinlock-protect-pm_idle arch/i386/kernel/apm.c
--- vanilla-linux-2.6.7-SKAS/arch/i386/kernel/apm.c~spinlock-protect-pm_idle 2004-08-17 20:21:20.000000000 +0200
+++ vanilla-linux-2.6.7-SKAS-paolo/arch/i386/kernel/apm.c 2004-08-17 20:57:07.000000000 +0200
@@ -2032,8 +2032,10 @@ static int __init apm_init(void)
if (HZ != 100)
idle_period = (idle_period * HZ) / 100;
if (idle_threshold < 100) {
+ lock_pm_idle();
original_pm_idle = pm_idle;
pm_idle = apm_cpu_idle;
+ unlock_pm_idle();
set_pm_idle = 1;
}

@@ -2044,8 +2046,10 @@ static void __exit apm_exit(void)
{
int error;

+ lock_pm_idle();
if (set_pm_idle)
pm_idle = original_pm_idle;
+ unlock_pm_idle();
if (((apm_info.bios.flags & APM_BIOS_DISENGAGED) == 0)
&& (apm_info.connection_version > 0x0100)) {
error = apm_engage_power_management(APM_DEVICE_ALL, 0);
diff -puN drivers/acpi/processor.c~spinlock-protect-pm_idle drivers/acpi/processor.c
--- vanilla-linux-2.6.7-SKAS/drivers/acpi/processor.c~spinlock-protect-pm_idle 2004-08-17 20:21:20.000000000 +0200
+++ vanilla-linux-2.6.7-SKAS-paolo/drivers/acpi/processor.c 2004-08-17 20:57:07.000000000 +0200
@@ -2334,8 +2334,10 @@ acpi_processor_add (
* platforms that only support C1.
*/
if ((pr->id == 0) && (pr->flags.power)) {
+ lock_pm_idle();
pm_idle_save = pm_idle;
pm_idle = acpi_processor_idle;
+ unlock_pm_idle();
}

printk(KERN_INFO PREFIX "%s [%s] (supports",
@@ -2373,8 +2375,11 @@ acpi_processor_remove (
pr = (struct acpi_processor *) acpi_driver_data(device);

/* Unregister the idle handler when processor #0 is removed. */
- if (pr->id == 0)
+ if (pr->id == 0) {
+ lock_pm_idle();
pm_idle = pm_idle_save;
+ unlock_pm_idle();
+ }

status = acpi_remove_notify_handler(pr->handle, ACPI_DEVICE_NOTIFY,
acpi_processor_notify);
diff -puN include/linux/pm.h~spinlock-protect-pm_idle include/linux/pm.h
--- vanilla-linux-2.6.7-SKAS/include/linux/pm.h~spinlock-protect-pm_idle 2004-08-17 20:22:20.000000000 +0200
+++ vanilla-linux-2.6.7-SKAS-paolo/include/linux/pm.h 2004-08-17 20:28:42.000000000 +0200
@@ -25,6 +25,7 @@

#include <linux/config.h>
#include <linux/list.h>
+#include <linux/spinlock.h>
#include <asm/atomic.h>

/*
@@ -193,6 +194,19 @@ static inline void pm_dev_idle(struct pm
extern void (*pm_idle)(void);
extern void (*pm_power_off)(void);

+extern spinlock_t pm_idle_lock;
+
+/*Not sure if this should be a semaphore...*/
+static inline int lock_pm_idle(void)
+{
+ spin_lock(&pm_idle_lock);
+ return 0;
+}
+static inline void unlock_pm_idle(void)
+{
+ spin_unlock(&pm_idle_lock);
+}
+
enum {
PM_SUSPEND_ON,
PM_SUSPEND_STANDBY,
diff -puN arch/i386/kernel/i386_ksyms.c~spinlock-protect-pm_idle arch/i386/kernel/i386_ksyms.c
--- vanilla-linux-2.6.7-SKAS/arch/i386/kernel/i386_ksyms.c~spinlock-protect-pm_idle 2004-08-17 21:00:33.000000000 +0200
+++ vanilla-linux-2.6.7-SKAS-paolo/arch/i386/kernel/i386_ksyms.c 2004-08-17 21:04:06.000000000 +0200
@@ -84,6 +84,7 @@ EXPORT_SYMBOL(probe_irq_mask);
EXPORT_SYMBOL(kernel_thread);
EXPORT_SYMBOL(pm_idle);
EXPORT_SYMBOL(pm_power_off);
+EXPORT_SYMBOL(pm_idle_lock);
EXPORT_SYMBOL(get_cmos_time);
EXPORT_SYMBOL(cpu_khz);
EXPORT_SYMBOL(apm_info);
diff -puN arch/arm26/kernel/armksyms.c~spinlock-protect-pm_idle arch/arm26/kernel/armksyms.c
--- vanilla-linux-2.6.7-SKAS/arch/arm26/kernel/armksyms.c~spinlock-protect-pm_idle 2004-08-17 21:00:33.000000000 +0200
+++ vanilla-linux-2.6.7-SKAS-paolo/arch/arm26/kernel/armksyms.c 2004-08-17 21:04:06.000000000 +0200
@@ -115,6 +115,7 @@ EXPORT_SYMBOL(disable_irq);
EXPORT_SYMBOL(set_irq_type);
EXPORT_SYMBOL(pm_idle);
EXPORT_SYMBOL(pm_power_off);
+EXPORT_SYMBOL(pm_idle_lock);

/* processor dependencies */
EXPORT_SYMBOL(__machine_arch_type);
diff -puN arch/sparc/kernel/sparc_ksyms.c~spinlock-protect-pm_idle arch/sparc/kernel/sparc_ksyms.c
--- vanilla-linux-2.6.7-SKAS/arch/sparc/kernel/sparc_ksyms.c~spinlock-protect-pm_idle 2004-08-17 21:00:34.000000000 +0200
+++ vanilla-linux-2.6.7-SKAS-paolo/arch/sparc/kernel/sparc_ksyms.c 2004-08-17 21:04:06.000000000 +0200
@@ -323,3 +323,4 @@ EXPORT_SYMBOL(do_BUG);

/* Sun Power Management Idle Handler */
EXPORT_SYMBOL(pm_idle);
+EXPORT_SYMBOL(pm_idle_lock);
diff -puN arch/x86_64/kernel/x8664_ksyms.c~spinlock-protect-pm_idle arch/x86_64/kernel/x8664_ksyms.c
--- vanilla-linux-2.6.7-SKAS/arch/x86_64/kernel/x8664_ksyms.c~spinlock-protect-pm_idle 2004-08-17 21:00:34.000000000 +0200
+++ vanilla-linux-2.6.7-SKAS-paolo/arch/x86_64/kernel/x8664_ksyms.c 2004-08-17 21:04:06.000000000 +0200
@@ -61,6 +61,7 @@ EXPORT_SYMBOL(probe_irq_mask);
EXPORT_SYMBOL(kernel_thread);
EXPORT_SYMBOL(pm_idle);
EXPORT_SYMBOL(pm_power_off);
+EXPORT_SYMBOL(pm_idle_lock);
EXPORT_SYMBOL(get_cmos_time);

EXPORT_SYMBOL_NOVERS(__down_failed);
diff -puN arch/sparc/kernel/pmc.c~spinlock-protect-pm_idle arch/sparc/kernel/pmc.c
--- vanilla-linux-2.6.7-SKAS/arch/sparc/kernel/pmc.c~spinlock-protect-pm_idle 2004-08-17 21:00:34.000000000 +0200
+++ vanilla-linux-2.6.7-SKAS-paolo/arch/sparc/kernel/pmc.c 2004-08-17 21:04:06.000000000 +0200
@@ -85,7 +85,9 @@ sbus_done:

#ifndef PMC_NO_IDLE
/* Assign power management IDLE handler */
+ lock_pm_idle();
pm_idle = pmc_swift_idle;
+ unlock_pm_idle();
#endif

printk(KERN_INFO "%s: power management initialized\n", PMC_DEVNAME);
diff -puN arch/sparc/kernel/apc.c~spinlock-protect-pm_idle arch/sparc/kernel/apc.c
--- vanilla-linux-2.6.7-SKAS/arch/sparc/kernel/apc.c~spinlock-protect-pm_idle 2004-08-17 21:00:34.000000000 +0200
+++ vanilla-linux-2.6.7-SKAS-paolo/arch/sparc/kernel/apc.c 2004-08-17 21:04:06.000000000 +0200
@@ -170,8 +170,11 @@ sbus_done:
}

/* Assign power management IDLE handler */
- if(!apc_no_idle)
+ if(!apc_no_idle) {
+ lock_pm_idle();
pm_idle = apc_swift_idle;
+ unlock_pm_idle();
+ }

printk(KERN_INFO "%s: power management initialized%s\n",
APC_DEVNAME, apc_no_idle ? " (CPU idle disabled)" : "");
diff -puN arch/cris/kernel/crisksyms.c~spinlock-protect-pm_idle arch/cris/kernel/crisksyms.c
--- vanilla-linux-2.6.7-SKAS/arch/cris/kernel/crisksyms.c~spinlock-protect-pm_idle 2004-08-17 21:05:13.000000000 +0200
+++ vanilla-linux-2.6.7-SKAS-paolo/arch/cris/kernel/crisksyms.c 2004-08-17 21:06:28.000000000 +0200
@@ -38,6 +38,8 @@ EXPORT_SYMBOL(disable_irq);
EXPORT_SYMBOL(kernel_thread);
EXPORT_SYMBOL(get_cmos_time);
EXPORT_SYMBOL(loops_per_usec);
+EXPORT_SYMBOL(pm_idle);
+EXPORT_SYMBOL(pm_idle_lock);

/* String functions */
EXPORT_SYMBOL(memcmp);
_