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SubjectRe: [PATCH] PM: Acquire device locks on suspend
Date
On Saturday, 5 of January 2008, Alan Stern wrote:
> On Sat, 5 Jan 2008, Rafael J. Wysocki wrote:
>
> > On Saturday, 5 of January 2008, Alan Stern wrote:
> > > On Sat, 5 Jan 2008, Rafael J. Wysocki wrote:
> > >
> > > > > Another thing to watch out for: Just in case somebody ends up calling
> > > > > destroy_suspended_device(dev) from within dev's own resume method, you
> > > > > should interchange the resume_device() and the list_move_tail()
> > > > > calls in dpm_resume().
> > > >
> > > > However, if we unregister them all at once after releasing pm_sleep_rwsem,
> > > > that shouldn't be necessary, right?
> > >
> > > It's still necessary, because destroy_suspended_device() still has to
> > > move the device from one list to another. You don't want it to end up
> > > on the dpm_locked list.
> >
> > Hmm. That means we'd have to do the same thing in dpm_power_up() in case
> > someone calls destroy_suspended_device() from resume_device_early(dev).
>
> Yes.
>
> > Still, even doing that is not enough, since someone can call
> > destroy_suspended_device() from a .suspend() routine and then the device
> > will end up on a wrong list just as well.
>
> That should never happen. The whole idea of destroy_suspended_device()
> is that the device couldn't be resumed and in fact should be
> unregistered because it is no longer working or no longer present. A
> suspend routine won't detect this sort of thing since it doesn't try to
> resume the device.
>
> But it wouldn't hurt to mention in the kerneldoc that
> destroy_suspended_device() is meant to be called only during a system
> resume.

Hmm. Please have a look at the appended patch.

I have removed the warning from device_del() and used list_empty() to detect
removed devices in the .suspend() routines. Is that viable?

Rafael


---
arch/x86/kernel/cpuid.c | 6
arch/x86/kernel/msr.c | 6
drivers/base/core.c | 67 +++++-
drivers/base/power/main.c | 454 ++++++++++++++++++++++++++-------------------
drivers/base/power/power.h | 12 +
include/linux/device.h | 8
6 files changed, 354 insertions(+), 199 deletions(-)
Index: linux-2.6/drivers/base/core.c
===================================================================
--- linux-2.6.orig/drivers/base/core.c
+++ linux-2.6/drivers/base/core.c
@@ -726,11 +726,20 @@ int device_add(struct device *dev)
{
struct device *parent = NULL;
struct class_interface *class_intf;
- int error = -EINVAL;
+ int error;
+
+ error = pm_sleep_lock();
+ if (error) {
+ dev_warn(dev, "Illegal %s during suspend\n", __FUNCTION__);
+ dump_stack();
+ return error;
+ }

dev = get_device(dev);
- if (!dev || !strlen(dev->bus_id))
- goto Error;
+ if (!dev || !strlen(dev->bus_id)) {
+ error = -EINVAL;
+ goto Done;
+ }

pr_debug("DEV: registering device: ID = '%s'\n", dev->bus_id);

@@ -795,6 +804,7 @@ int device_add(struct device *dev)
}
Done:
put_device(dev);
+ pm_sleep_unlock();
return error;
BusError:
device_pm_remove(dev);
@@ -1156,14 +1173,11 @@ error:
EXPORT_SYMBOL_GPL(device_create);

/**
- * device_destroy - removes a device that was created with device_create()
+ * find_device - finds a device that was created with device_create()
* @class: pointer to the struct class that this device was registered with
* @devt: the dev_t of the device that was previously registered
- *
- * This call unregisters and cleans up a device that was created with a
- * call to device_create().
*/
-void device_destroy(struct class *class, dev_t devt)
+static struct device *find_device(struct class *class, dev_t devt)
{
struct device *dev = NULL;
struct device *dev_tmp;
@@ -1176,12 +1190,49 @@ void device_destroy(struct class *class,
}
}
up(&class->sem);
+ return dev;
+}
+
+/**
+ * device_destroy - removes a device that was created with device_create()
+ * @class: pointer to the struct class that this device was registered with
+ * @devt: the dev_t of the device that was previously registered
+ *
+ * This call unregisters and cleans up a device that was created with a
+ * call to device_create().
+ */
+void device_destroy(struct class *class, dev_t devt)
+{
+ struct device *dev;

+ dev = find_device(class, devt);
if (dev)
device_unregister(dev);
}
EXPORT_SYMBOL_GPL(device_destroy);

+#ifdef CONFIG_PM_SLEEP
+/**
+ * destroy_suspended_device - asks the PM core to remove a suspended device
+ * @class: pointer to the struct class that this device was registered with
+ * @devt: the dev_t of the device that was previously registered
+ *
+ * This call causes the PM core to release and unregister a suspended device
+ * created with a call to device_create() (devices cannot be unregistered
+ * directly while suspended, since the PM core holds their semaphores at that
+ * time).
+ */
+void destroy_suspended_device(struct class *class, dev_t devt)
+{
+ struct device *dev;
+
+ dev = find_device(class, devt);
+ if (dev)
+ device_pm_destroy_suspended(dev);
+}
+EXPORT_SYMBOL_GPL(destroy_suspended_device);
+#endif /* CONFIG_PM_SLEEP */
+
/**
* device_rename - renames a device
* @dev: the pointer to the struct device to be renamed
Index: linux-2.6/include/linux/device.h
===================================================================
--- linux-2.6.orig/include/linux/device.h
+++ linux-2.6/include/linux/device.h
@@ -521,6 +521,14 @@ extern struct device *device_create(stru
dev_t devt, const char *fmt, ...)
__attribute__((format(printf,4,5)));
extern void device_destroy(struct class *cls, dev_t devt);
+#ifdef CONFIG_PM_SLEEP
+extern void destroy_suspended_device(struct class *cls, dev_t devt);
+#else /* !CONFIG_PM_SLEEP */
+static inline void destroy_suspended_device(struct class *cls, dev_t devt)
+{
+ device_destroy(cls, devt);
+}
+#endif /* !CONFIG_PM_SLEEP */

/*
* Platform "fixup" functions - allow the platform to have their say
Index: linux-2.6/drivers/base/power/power.h
===================================================================
--- linux-2.6.orig/drivers/base/power/power.h
+++ linux-2.6/drivers/base/power/power.h
@@ -20,6 +20,9 @@ static inline struct device *to_device(s

extern void device_pm_add(struct device *);
extern void device_pm_remove(struct device *);
+extern void device_pm_destroy_suspended(struct device *);
+extern int pm_sleep_lock(void);
+extern void pm_sleep_unlock(void);

#else /* CONFIG_PM_SLEEP */

@@ -32,6 +35,15 @@ static inline void device_pm_remove(stru
{
}

+static inline int pm_sleep_lock(void)
+{
+ return 0;
+}
+
+static inline void pm_sleep_unlock(void)
+{
+}
+
#endif

#ifdef CONFIG_PM
Index: linux-2.6/drivers/base/power/main.c
===================================================================
--- linux-2.6.orig/drivers/base/power/main.c
+++ linux-2.6/drivers/base/power/main.c
@@ -24,17 +24,38 @@
#include <linux/mutex.h>
#include <linux/pm.h>
#include <linux/resume-trace.h>
+#include <linux/rwsem.h>

#include "../base.h"
#include "power.h"

+/*
+ * The entries in the dpm_active list are in a depth first order, simply
+ * because children are guaranteed to be discovered after parents, and
+ * are inserted at the back of the list on discovery.
+ *
+ * All the other lists are kept in the same order, for consistency.
+ * However the lists aren't always traversed in the same order.
+ * Semaphores must be acquired from the top (i.e., front) down
+ * and released in the opposite order. Devices must be suspended
+ * from the bottom (i.e., end) up and resumed in the opposite order.
+ * That way no parent will be suspended while it still has an active
+ * child.
+ *
+ * Since device_pm_add() may be called with a device semaphore held,
+ * we must never try to acquire a device semaphore while holding
+ * dpm_list_mutex.
+ */
+
LIST_HEAD(dpm_active);
+static LIST_HEAD(dpm_locked);
static LIST_HEAD(dpm_off);
static LIST_HEAD(dpm_off_irq);

-static DEFINE_MUTEX(dpm_mtx);
static DEFINE_MUTEX(dpm_list_mtx);

+static DECLARE_RWSEM(pm_sleep_rwsem);
+
int (*platform_enable_wakeup)(struct device *dev, int is_on);


@@ -53,29 +74,124 @@ void device_pm_remove(struct device *dev
pr_debug("PM: Removing info for %s:%s\n",
dev->bus ? dev->bus->name : "No Bus",
kobject_name(&dev->kobj));
+
+ /* Don't remove a device while the PM core has it locked for suspend */
+ down(&dev->sem);
mutex_lock(&dpm_list_mtx);
dpm_sysfs_remove(dev);
list_del_init(&dev->power.entry);
mutex_unlock(&dpm_list_mtx);
+ up(&dev->sem);
+}
+
+void device_pm_destroy_suspended(struct device *dev)
+{
+ pr_debug("PM: Removing suspended device %s:%s\n",
+ dev->bus ? dev->bus->name : "No Bus",
+ kobject_name(&dev->kobj));
+ mutex_lock(&dpm_list_mtx);
+ list_del_init(&dev->power.entry);
+ mutex_unlock(&dpm_list_mtx);
+ up(&dev->sem);
+ device_unregister(dev);
+}
+
+/**
+ * pm_sleep_lock - mutual exclusion for registration and suspend
+ *
+ * Returns 0 if no suspend is underway and device registration
+ * may proceed, otherwise -EBUSY.
+ */
+int pm_sleep_lock(void)
+{
+ if (down_read_trylock(&pm_sleep_rwsem))
+ return 0;
+ return -EBUSY;
+}
+
+/**
+ * pm_sleep_unlock - mutual exclusion for registration and suspend
+ *
+ * This routine undoes the effect of device_pm_add_lock
+ * when a device's registration is complete.
+ */
+void pm_sleep_unlock(void)
+{
+ up_read(&pm_sleep_rwsem);
}


/*------------------------- Resume routines -------------------------*/

/**
- * resume_device - Restore state for one device.
+ * resume_device_early - Power on one device (early resume).
* @dev: Device.
*
+ * Must be called with interrupts disabled.
*/
-
-static int resume_device(struct device * dev)
+static int resume_device_early(struct device *dev)
{
int error = 0;

TRACE_DEVICE(dev);
TRACE_RESUME(0);

- down(&dev->sem);
+ if (dev->bus && dev->bus->resume_early) {
+ dev_dbg(dev,"EARLY resume\n");
+ error = dev->bus->resume_early(dev);
+ }
+
+ TRACE_RESUME(error);
+ return error;
+}
+
+/**
+ * dpm_power_up - Power on all regular (non-sysdev) devices.
+ *
+ * Walk the dpm_off_irq list and power each device up. This
+ * is used for devices that required they be powered down with
+ * interrupts disabled. As devices are powered on, they are moved
+ * to the dpm_off list.
+ *
+ * Interrupts must be disabled when calling this.
+ */
+static void dpm_power_up(void)
+{
+ while (!list_empty(&dpm_off_irq)) {
+ struct list_head *entry = dpm_off_irq.next;
+ struct device *dev = to_device(entry);
+
+ list_move_tail(entry, &dpm_off);
+ resume_device_early(dev);
+ }
+}
+
+/**
+ * device_power_up - Turn on all devices that need special attention.
+ *
+ * Power on system devices, then devices that required we shut them down
+ * with interrupts disabled.
+ *
+ * Must be called with interrupts disabled.
+ */
+void device_power_up(void)
+{
+ sysdev_resume();
+ dpm_power_up();
+}
+EXPORT_SYMBOL_GPL(device_power_up);
+
+/**
+ * resume_device - Restore state for one device.
+ * @dev: Device.
+ *
+ */
+static int resume_device(struct device *dev)
+{
+ int error = 0;
+
+ TRACE_DEVICE(dev);
+ TRACE_RESUME(0);

if (dev->bus && dev->bus->resume) {
dev_dbg(dev,"resuming\n");
@@ -92,126 +208,68 @@ static int resume_device(struct device *
error = dev->class->resume(dev);
}

- up(&dev->sem);
-
TRACE_RESUME(error);
return error;
}

-
-static int resume_device_early(struct device * dev)
+/**
+ * dpm_resume - Resume every device.
+ *
+ * Resume the devices that have either not gone through
+ * the late suspend, or that did go through it but also
+ * went through the early resume.
+ *
+ * Take devices from the dpm_off_list, resume them,
+ * and put them on the dpm_locked list.
+ */
+static void dpm_resume(void)
{
- int error = 0;
+ while(!list_empty(&dpm_off)) {
+ struct list_head *entry = dpm_off.next;
+ struct device *dev = to_device(entry);

- TRACE_DEVICE(dev);
- TRACE_RESUME(0);
- if (dev->bus && dev->bus->resume_early) {
- dev_dbg(dev,"EARLY resume\n");
- error = dev->bus->resume_early(dev);
+ resume_device(dev);
+ list_move_tail(entry, &dpm_locked);
}
- TRACE_RESUME(error);
- return error;
}

-/*
- * Resume the devices that have either not gone through
- * the late suspend, or that did go through it but also
- * went through the early resume
+/**
+ * unlock_all_devices - Release each device's semaphore
+ *
+ * Go through the dpm_off list. Put each device on the dpm_active
+ * list and unlock it.
*/
-static void dpm_resume(void)
+static void unlock_all_devices(void)
{
mutex_lock(&dpm_list_mtx);
- while(!list_empty(&dpm_off)) {
- struct list_head * entry = dpm_off.next;
- struct device * dev = to_device(entry);
-
- get_device(dev);
- list_move_tail(entry, &dpm_active);
-
- mutex_unlock(&dpm_list_mtx);
- resume_device(dev);
- mutex_lock(&dpm_list_mtx);
- put_device(dev);
- }
+ while (!list_empty(&dpm_locked)) {
+ struct list_head *entry = dpm_locked.prev;
+ struct device *dev = to_device(entry);
+
+ list_move(entry, &dpm_active);
+ up(&dev->sem);
+ }
mutex_unlock(&dpm_list_mtx);
}

-
/**
* device_resume - Restore state of each device in system.
*
- * Walk the dpm_off list, remove each entry, resume the device,
- * then add it to the dpm_active list.
+ * Resume all the devices, unlock them all, and allow new
+ * devices to be registered once again.
*/
-
void device_resume(void)
{
might_sleep();
- mutex_lock(&dpm_mtx);
dpm_resume();
- mutex_unlock(&dpm_mtx);
+ unlock_all_devices();
+ up_write(&pm_sleep_rwsem);
}
-
EXPORT_SYMBOL_GPL(device_resume);


-/**
- * dpm_power_up - Power on some devices.
- *
- * Walk the dpm_off_irq list and power each device up. This
- * is used for devices that required they be powered down with
- * interrupts disabled. As devices are powered on, they are moved
- * to the dpm_active list.
- *
- * Interrupts must be disabled when calling this.
- */
-
-static void dpm_power_up(void)
-{
- while(!list_empty(&dpm_off_irq)) {
- struct list_head * entry = dpm_off_irq.next;
- struct device * dev = to_device(entry);
-
- list_move_tail(entry, &dpm_off);
- resume_device_early(dev);
- }
-}
-
-
-/**
- * device_power_up - Turn on all devices that need special attention.
- *
- * Power on system devices then devices that required we shut them down
- * with interrupts disabled.
- * Called with interrupts disabled.
- */
-
-void device_power_up(void)
-{
- sysdev_resume();
- dpm_power_up();
-}
-
-EXPORT_SYMBOL_GPL(device_power_up);
-
-
/*------------------------- Suspend routines -------------------------*/

-/*
- * The entries in the dpm_active list are in a depth first order, simply
- * because children are guaranteed to be discovered after parents, and
- * are inserted at the back of the list on discovery.
- *
- * All list on the suspend path are done in reverse order, so we operate
- * on the leaves of the device tree (or forests, depending on how you want
- * to look at it ;) first. As nodes are removed from the back of the list,
- * they are inserted into the front of their destintation lists.
- *
- * Things are the reverse on the resume path - iterations are done in
- * forward order, and nodes are inserted at the back of their destination
- * lists. This way, the ancestors will be accessed before their descendents.
- */
-
static inline char *suspend_verb(u32 event)
{
switch (event) {
@@ -222,7 +280,6 @@ static inline char *suspend_verb(u32 eve
}
}

-
static void
suspend_device_dbg(struct device *dev, pm_message_t state, char *info)
{
@@ -232,16 +289,70 @@ suspend_device_dbg(struct device *dev, p
}

/**
- * suspend_device - Save state of one device.
+ * suspend_device_late - Shut down one device (late suspend).
* @dev: Device.
* @state: Power state device is entering.
+ *
+ * This is called with interrupts off and only a single CPU running.
*/
+static int suspend_device_late(struct device *dev, pm_message_t state)
+{
+ int error = 0;

-static int suspend_device(struct device * dev, pm_message_t state)
+ if (dev->bus && dev->bus->suspend_late) {
+ suspend_device_dbg(dev, state, "LATE ");
+ error = dev->bus->suspend_late(dev, state);
+ suspend_report_result(dev->bus->suspend_late, error);
+ }
+ return error;
+}
+
+/**
+ * device_power_down - Shut down special devices.
+ * @state: Power state to enter.
+ *
+ * Power down devices that require interrupts to be disabled
+ * and move them from the dpm_off list to the dpm_off_irq list.
+ * Then power down system devices.
+ *
+ * Must be called with interrupts disabled and only one CPU running.
+ */
+int device_power_down(pm_message_t state)
+{
+ int error = 0;
+
+ while (!list_empty(&dpm_off)) {
+ struct list_head *entry = dpm_off.prev;
+ struct device *dev = to_device(entry);
+
+ error = suspend_device_late(dev, state);
+ if (error) {
+ printk(KERN_ERR "Could not power down device %s: "
+ "error %d\n",
+ kobject_name(&dev->kobj), error);
+ break;
+ }
+ if (!list_empty(&dev->power.entry))
+ list_move(&dev->power.entry, &dpm_off_irq);
+ }
+
+ if (!error)
+ error = sysdev_suspend(state);
+ if (error)
+ dpm_power_up();
+ return error;
+}
+EXPORT_SYMBOL_GPL(device_power_down);
+
+/**
+ * suspend_device - Save state of one device.
+ * @dev: Device.
+ * @state: Power state device is entering.
+ */
+int suspend_device(struct device *dev, pm_message_t state)
{
int error = 0;

- down(&dev->sem);
if (dev->power.power_state.event) {
dev_dbg(dev, "PM: suspend %d-->%d\n",
dev->power.power_state.event, state.event);
@@ -264,123 +375,96 @@ static int suspend_device(struct device
error = dev->bus->suspend(dev, state);
suspend_report_result(dev->bus->suspend, error);
}
- up(&dev->sem);
return error;
}

-
-/*
- * This is called with interrupts off, only a single CPU
- * running. We can't acquire a mutex or semaphore (and we don't
- * need the protection)
+/**
+ * dpm_suspend - Suspend every device.
+ * @state: Power state to put each device in.
+ *
+ * Walk the dpm_locked list. Suspend each device and move it
+ * to the dpm_off list.
+ *
+ * (For historical reasons, if it returns -EAGAIN, that used to mean
+ * that the device would be called again with interrupts disabled.
+ * These days, we use the "suspend_late()" callback for that, so we
+ * print a warning and consider it an error).
*/
-static int suspend_device_late(struct device *dev, pm_message_t state)
+static int dpm_suspend(pm_message_t state)
{
int error = 0;

- if (dev->bus && dev->bus->suspend_late) {
- suspend_device_dbg(dev, state, "LATE ");
- error = dev->bus->suspend_late(dev, state);
- suspend_report_result(dev->bus->suspend_late, error);
+ while (!list_empty(&dpm_locked)) {
+ struct list_head *entry = dpm_locked.prev;
+ struct device *dev = to_device(entry);
+
+ error = suspend_device(dev, state);
+ if (error) {
+ printk(KERN_ERR "Could not suspend device %s: "
+ "error %d%s\n",
+ kobject_name(&dev->kobj),
+ error,
+ (error == -EAGAIN ?
+ " (please convert to suspend_late)" :
+ ""));
+ break;
+ }
+ if (!list_empty(&dev->power.entry))
+ list_move(&dev->power.entry, &dpm_off);
}
+
return error;
}

/**
- * device_suspend - Save state and stop all devices in system.
- * @state: Power state to put each device in.
- *
- * Walk the dpm_active list, call ->suspend() for each device, and move
- * it to the dpm_off list.
- *
- * (For historical reasons, if it returns -EAGAIN, that used to mean
- * that the device would be called again with interrupts disabled.
- * These days, we use the "suspend_late()" callback for that, so we
- * print a warning and consider it an error).
- *
- * If we get a different error, try and back out.
- *
- * If we hit a failure with any of the devices, call device_resume()
- * above to bring the suspended devices back to life.
+ * lock_all_devices - Acquire every device's semaphore
*
+ * Go through the dpm_active list. Carefully lock each device's
+ * semaphore and put it in on the dpm_locked list.
*/
-
-int device_suspend(pm_message_t state)
+static void lock_all_devices(void)
{
- int error = 0;
-
- might_sleep();
- mutex_lock(&dpm_mtx);
mutex_lock(&dpm_list_mtx);
- while (!list_empty(&dpm_active) && error == 0) {
- struct list_head * entry = dpm_active.prev;
- struct device * dev = to_device(entry);
-
+ while (!list_empty(&dpm_active)) {
+ struct list_head *entry = dpm_active.next;
+ struct device *dev = to_device(entry);
+
+ /* Required locking order is dev->sem first,
+ * then dpm_list_mutex. Hence this awkward code.
+ */
get_device(dev);
mutex_unlock(&dpm_list_mtx);
-
- error = suspend_device(dev, state);
-
+ down(&dev->sem);
mutex_lock(&dpm_list_mtx);

- /* Check if the device got removed */
- if (!list_empty(&dev->power.entry)) {
- /* Move it to the dpm_off list */
- if (!error)
- list_move(&dev->power.entry, &dpm_off);
- }
- if (error)
- printk(KERN_ERR "Could not suspend device %s: "
- "error %d%s\n",
- kobject_name(&dev->kobj), error,
- error == -EAGAIN ? " (please convert to suspend_late)" : "");
+ if (list_empty(entry))
+ up(&dev->sem); /* Device was removed */
+ else
+ list_move_tail(entry, &dpm_locked);
put_device(dev);
}
mutex_unlock(&dpm_list_mtx);
- if (error)
- dpm_resume();
-
- mutex_unlock(&dpm_mtx);
- return error;
}

-EXPORT_SYMBOL_GPL(device_suspend);
-
/**
- * device_power_down - Shut down special devices.
- * @state: Power state to enter.
+ * device_suspend - Save state and stop all devices in system.
*
- * Walk the dpm_off_irq list, calling ->power_down() for each device that
- * couldn't power down the device with interrupts enabled. When we're
- * done, power down system devices.
+ * Prevent new devices from being registered, then lock all devices
+ * and suspend them.
*/
-
-int device_power_down(pm_message_t state)
+int device_suspend(pm_message_t state)
{
- int error = 0;
- struct device * dev;
-
- while (!list_empty(&dpm_off)) {
- struct list_head * entry = dpm_off.prev;
-
- dev = to_device(entry);
- error = suspend_device_late(dev, state);
- if (error)
- goto Error;
- list_move(&dev->power.entry, &dpm_off_irq);
- }
+ int error;

- error = sysdev_suspend(state);
- Done:
+ might_sleep();
+ down_write(&pm_sleep_rwsem);
+ lock_all_devices();
+ error = dpm_suspend(state);
+ if (error)
+ device_resume();
return error;
- Error:
- printk(KERN_ERR "Could not power down device %s: "
- "error %d\n", kobject_name(&dev->kobj), error);
- dpm_power_up();
- goto Done;
}
-
-EXPORT_SYMBOL_GPL(device_power_down);
+EXPORT_SYMBOL_GPL(device_suspend);

void __suspend_report_result(const char *function, void *fn, int ret)
{
Index: linux-2.6/arch/x86/kernel/msr.c
===================================================================
--- linux-2.6.orig/arch/x86/kernel/msr.c
+++ linux-2.6/arch/x86/kernel/msr.c
@@ -155,15 +155,15 @@ static int __cpuinit msr_class_cpu_callb

switch (action) {
case CPU_UP_PREPARE:
- case CPU_UP_PREPARE_FROZEN:
err = msr_device_create(cpu);
break;
case CPU_UP_CANCELED:
- case CPU_UP_CANCELED_FROZEN:
case CPU_DEAD:
- case CPU_DEAD_FROZEN:
msr_device_destroy(cpu);
break;
+ case CPU_UP_CANCELED_FROZEN:
+ destroy_suspended_device(msr_class, MKDEV(MSR_MAJOR, cpu));
+ break;
}
return err ? NOTIFY_BAD : NOTIFY_OK;
}
Index: linux-2.6/arch/x86/kernel/cpuid.c
===================================================================
--- linux-2.6.orig/arch/x86/kernel/cpuid.c
+++ linux-2.6/arch/x86/kernel/cpuid.c
@@ -157,15 +157,15 @@ static int __cpuinit cpuid_class_cpu_cal

switch (action) {
case CPU_UP_PREPARE:
- case CPU_UP_PREPARE_FROZEN:
err = cpuid_device_create(cpu);
break;
case CPU_UP_CANCELED:
- case CPU_UP_CANCELED_FROZEN:
case CPU_DEAD:
- case CPU_DEAD_FROZEN:
cpuid_device_destroy(cpu);
break;
+ case CPU_UP_CANCELED_FROZEN:
+ destroy_suspended_device(cpuid_class, MKDEV(CPUID_MAJOR, cpu));
+ break;
}
return err ? NOTIFY_BAD : NOTIFY_OK;
}

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