[PATCH 1/3] PM: Handle device registrations during suspend/resume

[PATCH 1/3] PM: Handle device registrations during suspend/resume

[Rafael J. Wysocki]

From: Rafael J. Wysocki <rjw@sisk.pl>

Modify the PM core to protect its data structures, specifically the
dpm_active list, from being corrupted if a child of the currently
suspending device is registered concurrently with its ->suspend()
callback.  In that case, since the new device (the child) is added
to dpm_active after its parent, the PM core will attempt to
suspend it after the parent, which is wrong.

Introduce a new member of struct dev_pm_info, called 'sleeping',
and use it to check if the parent of the device being added to
dpm_active has been suspended, in which case the device registration
fails.  Also, use 'sleeping' for checking if the ordering of devices
on dpm_active is correct.

Introduce variable 'all_sleeping' that will be set to 'true' once all
devices have been suspended and make new device registrations fail
until 'all_sleeping' is reset to 'false', in order to avoid having
unsuspended devices around while the system is going into a sleep state.

Remove pm_sleep_rwsem which is not necessary any more.

Special thanks to Alan Stern for discussions and suggestions that
lead to the creation of this patch.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
---
 Documentation/power/devices.txt |    5 +++
 drivers/base/core.c             |    6 +++-
 drivers/base/power/main.c       |   57 ++++++++++++++++++----------------------
 drivers/base/power/power.h      |   23 ++--------------
 include/linux/pm.h              |    1 
 5 files changed, 40 insertions(+), 52 deletions(-)

Index: linux-2.6/include/linux/pm.h
===================================================================
--- linux-2.6.orig/include/linux/pm.h
+++ linux-2.6/include/linux/pm.h
@@ -183,6 +183,7 @@ typedef struct pm_message {
 struct dev_pm_info {
 	pm_message_t		power_state;
 	unsigned		can_wakeup:1;
+	bool			sleeping:1;	/* Owned by the PM core */
 #ifdef	CONFIG_PM_SLEEP
 	unsigned		should_wakeup:1;
 	struct list_head	entry;
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
@@ -54,7 +54,8 @@ static LIST_HEAD(dpm_destroy);
 
 static DEFINE_MUTEX(dpm_list_mtx);
 
-static DECLARE_RWSEM(pm_sleep_rwsem);
+/* 'true' if all devices have been suspended, protected by dpm_list_mtx */
+static bool all_sleeping;
 
 int (*platform_enable_wakeup)(struct device *dev, int is_on);
 
@@ -62,14 +63,28 @@ int (*platform_enable_wakeup)(struct dev
  *	device_pm_add - add a device to the list of active devices
  *	@dev:	Device to be added to the list
  */
-void device_pm_add(struct device *dev)
+int device_pm_add(struct device *dev)
 {
+	int error = 0;
+
 	pr_debug("PM: Adding info for %s:%s\n",
 		 dev->bus ? dev->bus->name : "No Bus",
 		 kobject_name(&dev->kobj));
 	mutex_lock(&dpm_list_mtx);
-	list_add_tail(&dev->power.entry, &dpm_active);
+	if ((dev->parent && dev->parent->power.sleeping) || all_sleeping) {
+		if (dev->parent->power.sleeping)
+			dev_warn(dev,
+				"parent %s is sleeping, will not add\n",
+				dev->parent->bus_id);
+		else
+			dev_warn(dev, "devices are sleeping, will not add\n");
+		WARN_ON(true);
+		error = -EBUSY;
+	} else {
+		list_add_tail(&dev->power.entry, &dpm_active);
+	}
 	mutex_unlock(&dpm_list_mtx);
+	return error;
 }
 
 /**
@@ -107,32 +122,6 @@ void device_pm_schedule_removal(struct d
 }
 EXPORT_SYMBOL_GPL(device_pm_schedule_removal);
 
-/**
- *	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 -------------------------*/
 
 /**
@@ -242,11 +231,13 @@ static int resume_device(struct device *
 static void dpm_resume(void)
 {
 	mutex_lock(&dpm_list_mtx);
+	all_sleeping = false;
 	while(!list_empty(&dpm_off)) {
 		struct list_head *entry = dpm_off.next;
 		struct device *dev = to_device(entry);
 
 		list_move_tail(entry, &dpm_active);
+		dev->power.sleeping = false;
 		mutex_unlock(&dpm_list_mtx);
 		resume_device(dev);
 		mutex_lock(&dpm_list_mtx);
@@ -285,7 +276,6 @@ void device_resume(void)
 	might_sleep();
 	dpm_resume();
 	unregister_dropped_devices();
-	up_write(&pm_sleep_rwsem);
 }
 EXPORT_SYMBOL_GPL(device_resume);
 
@@ -426,6 +416,9 @@ static int dpm_suspend(pm_message_t stat
 		struct list_head *entry = dpm_active.prev;
 		struct device *dev = to_device(entry);
 
+		WARN_ON(dev->parent && dev->parent->power.sleeping);
+
+		dev->power.sleeping = true;
 		mutex_unlock(&dpm_list_mtx);
 		error = suspend_device(dev, state);
 		mutex_lock(&dpm_list_mtx);
@@ -437,11 +430,14 @@ static int dpm_suspend(pm_message_t stat
 					(error == -EAGAIN ?
 					" (please convert to suspend_late)" :
 					""));
+			dev->power.sleeping = false;
 			break;
 		}
 		if (!list_empty(&dev->power.entry))
 			list_move(&dev->power.entry, &dpm_off);
 	}
+	if (!error)
+		all_sleeping = true;
 	mutex_unlock(&dpm_list_mtx);
 
 	return error;
@@ -459,7 +455,6 @@ int device_suspend(pm_message_t state)
 	int error;
 
 	might_sleep();
-	down_write(&pm_sleep_rwsem);
 	error = dpm_suspend(state);
 	if (error)
 		device_resume();
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
@@ -11,30 +11,13 @@ static inline struct device *to_device(s
 	return container_of(entry, struct device, power.entry);
 }
 
-extern void device_pm_add(struct device *);
+extern int device_pm_add(struct device *);
 extern void device_pm_remove(struct device *);
-extern int pm_sleep_lock(void);
-extern void pm_sleep_unlock(void);
 
 #else /* CONFIG_PM_SLEEP */
 
-
-static inline void device_pm_add(struct device *dev)
-{
-}
-
-static inline void device_pm_remove(struct device *dev)
-{
-}
-
-static inline int pm_sleep_lock(void)
-{
-	return 0;
-}
-
-static inline void pm_sleep_unlock(void)
-{
-}
+static inline int device_pm_add(struct device *dev) { return 0; }
+static inline void device_pm_remove(struct device *dev) {}
 
 #endif
 
Index: linux-2.6/drivers/base/core.c
===================================================================
--- linux-2.6.orig/drivers/base/core.c
+++ linux-2.6/drivers/base/core.c
@@ -815,7 +815,11 @@ int device_add(struct device *dev)
 	error = dpm_sysfs_add(dev);
 	if (error)
 		goto PMError;
-	device_pm_add(dev);
+	error = device_pm_add(dev);
+	if (error) {
+		dpm_sysfs_remove(dev);
+		goto PMError;
+	}
 	error = bus_add_device(dev);
 	if (error)
 		goto BusError;
Index: linux-2.6/Documentation/power/devices.txt
===================================================================
--- linux-2.6.orig/Documentation/power/devices.txt
+++ linux-2.6/Documentation/power/devices.txt
@@ -196,6 +196,11 @@ its parent; and can't be removed or susp
 
 The policy is that the device tree should match hardware bus topology.
 (Or at least the control bus, for devices which use multiple busses.)
+In particular, this means that a device registration may fail if the parent of
+the device is suspending (ie. has been chosen by the PM core as the next
+device to suspend) or has already suspended, as well as after all of the other
+devices have been suspended.  Device drivers must be prepared to cope with such
+situations.
 
 
 Suspending Devices

[PATCH 2/3] Driver core: Call device_pm_add() after bus_add_device() in device_add()

[Rafael J. Wysocki]

From: Rafael J. Wysocki <rjw@sisk.pl>

Include dpm_sysfs_add() into device_pm_add(), in analogy with
device_pm_remove(), and modify device_add() to call the latter after
bus_add_device(), to avoid situations in which the PM core may
attempt to suspend a device the registration of which has not been
successful.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
---
 drivers/base/core.c       |   15 +++++----------
 drivers/base/power/main.c |    4 +++-
 2 files changed, 8 insertions(+), 11 deletions(-)

Index: linux-2.6/drivers/base/core.c
===================================================================
--- linux-2.6.orig/drivers/base/core.c
+++ linux-2.6/drivers/base/core.c
@@ -812,17 +812,12 @@ int device_add(struct device *dev)
 	error = device_add_attrs(dev);
 	if (error)
 		goto AttrsError;
-	error = dpm_sysfs_add(dev);
-	if (error)
-		goto PMError;
-	error = device_pm_add(dev);
-	if (error) {
-		dpm_sysfs_remove(dev);
-		goto PMError;
-	}
 	error = bus_add_device(dev);
 	if (error)
 		goto BusError;
+	error = device_pm_add(dev);
+	if (error)
+		goto PMError;
 	kobject_uevent(&dev->kobj, KOBJ_ADD);
 	bus_attach_device(dev);
 	if (parent)
@@ -842,9 +837,9 @@ int device_add(struct device *dev)
  Done:
 	put_device(dev);
 	return error;
- BusError:
-	device_pm_remove(dev);
  PMError:
+	bus_remove_device(dev);
+ BusError:
 	if (dev->bus)
 		blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
 					     BUS_NOTIFY_DEL_DEVICE, dev);
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
@@ -81,7 +81,9 @@ int device_pm_add(struct device *dev)
 		WARN_ON(true);
 		error = -EBUSY;
 	} else {
-		list_add_tail(&dev->power.entry, &dpm_active);
+		error = dpm_sysfs_add(dev);
+		if (!error)
+			list_add_tail(&dev->power.entry, &dpm_active);
 	}
 	mutex_unlock(&dpm_list_mtx);
 	return error;

[PATCH 3/3] PM: make wakeup flags available whenever CONFIG_PM is set

[Rafael J. Wysocki]

From: Alan Stern <stern@rowland.harvard.edu>

The various wakeup flags and their accessor macros in struct
dev_pm_info should be available whenever CONFIG_PM is enabled, not
just when CONFIG_PM_SLEEP is on.  Otherwise remote wakeup won't always
be configurable for runtime power management.  This patch (as1056)
fixes the oversight.

[rjw: rebased the patch on top of the previous two.]

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
CC: David Brownell <david-b@pacbell.net>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
---
 drivers/base/power/main.c  |    2 -
 drivers/base/power/sysfs.c |    2 +
 include/linux/pm.h         |   64 +++++++++++++++++++++++++--------------------
 3 files changed, 38 insertions(+), 30 deletions(-)

Index: linux-2.6/include/linux/pm.h
===================================================================
--- linux-2.6.orig/include/linux/pm.h
+++ linux-2.6/include/linux/pm.h
@@ -183,9 +183,9 @@ typedef struct pm_message {
 struct dev_pm_info {
 	pm_message_t		power_state;
 	unsigned		can_wakeup:1;
+	unsigned		should_wakeup:1;
 	bool			sleeping:1;	/* Owned by the PM core */
 #ifdef	CONFIG_PM_SLEEP
-	unsigned		should_wakeup:1;
 	struct list_head	entry;
 #endif
 };
@@ -198,11 +198,6 @@ extern void device_resume(void);
 extern int device_suspend(pm_message_t state);
 extern int device_prepare_suspend(pm_message_t state);
 
-#define device_set_wakeup_enable(dev,val) \
-	((dev)->power.should_wakeup = !!(val))
-#define device_may_wakeup(dev) \
-	(device_can_wakeup(dev) && (dev)->power.should_wakeup)
-
 extern void __suspend_report_result(const char *function, void *fn, int ret);
 
 #define suspend_report_result(fn, ret)					\
@@ -210,6 +205,35 @@ extern void __suspend_report_result(cons
 		__suspend_report_result(__FUNCTION__, fn, ret);		\
 	} while (0)
 
+#else /* !CONFIG_PM_SLEEP */
+
+static inline int device_suspend(pm_message_t state)
+{
+	return 0;
+}
+
+#define suspend_report_result(fn, ret) 		do {} while (0)
+
+#endif /* !CONFIG_PM_SLEEP */
+
+#ifdef CONFIG_PM
+
+/* changes to device_may_wakeup take effect on the next pm state change.
+ * by default, devices should wakeup if they can.
+ */
+#define device_can_wakeup(dev) \
+	((dev)->power.can_wakeup)
+#define device_init_wakeup(dev,val) \
+	do { \
+		device_can_wakeup(dev) = !!(val); \
+		device_set_wakeup_enable(dev,val); \
+	} while(0)
+
+#define device_set_wakeup_enable(dev,val) \
+	((dev)->power.should_wakeup = !!(val))
+#define device_may_wakeup(dev) \
+	(device_can_wakeup(dev) && (dev)->power.should_wakeup)
+
 /*
  * Platform hook to activate device wakeup capability, if that's not already
  * handled by enable_irq_wake() etc.
@@ -224,35 +248,19 @@ static inline int call_platform_enable_w
 	return 0;
 }
 
-#else /* !CONFIG_PM_SLEEP */
-
-static inline int device_suspend(pm_message_t state)
-{
-	return 0;
-}
-
-#define device_set_wakeup_enable(dev,val)	do{}while(0)
-#define device_may_wakeup(dev)			(0)
+#else /* !CONFIG_PM */
 
-#define suspend_report_result(fn, ret) do { } while (0)
+#define device_can_wakeup(dev)			0
+#define device_init_wakeup(dev,val)		do {} while (0)
+#define device_set_wakeup_enable(dev,val)	do {} while (0)
+#define device_may_wakeup(dev)			0
 
 static inline int call_platform_enable_wakeup(struct device *dev, int is_on)
 {
 	return 0;
 }
 
-#endif /* !CONFIG_PM_SLEEP */
-
-/* changes to device_may_wakeup take effect on the next pm state change.
- * by default, devices should wakeup if they can.
- */
-#define device_can_wakeup(dev) \
-	((dev)->power.can_wakeup)
-#define device_init_wakeup(dev,val) \
-	do { \
-		device_can_wakeup(dev) = !!(val); \
-		device_set_wakeup_enable(dev,val); \
-	} while(0)
+#endif /* !CONFIG_PM */
 
 /*
  * Global Power Management flags
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
@@ -57,8 +57,6 @@ static DEFINE_MUTEX(dpm_list_mtx);
 /* 'true' if all devices have been suspended, protected by dpm_list_mtx */
 static bool all_sleeping;
 
-int (*platform_enable_wakeup)(struct device *dev, int is_on);
-
 /**
  *	device_pm_add - add a device to the list of active devices
  *	@dev:	Device to be added to the list
Index: linux-2.6/drivers/base/power/sysfs.c
===================================================================
--- linux-2.6.orig/drivers/base/power/sysfs.c
+++ linux-2.6/drivers/base/power/sysfs.c
@@ -6,6 +6,8 @@
 #include <linux/string.h>
 #include "power.h"
 
+int (*platform_enable_wakeup)(struct device *dev, int is_on);
+
 
 /*
  *	wakeup - Report/change current wakeup option for device

Re: [PATCH 1/3] PM: Handle device registrations during suspend/resume

[Pavel Machek]

On Wed 2008-03-12 00:57:22, Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rjw@sisk.pl>
> 
> Modify the PM core to protect its data structures, specifically the
> dpm_active list, from being corrupted if a child of the currently
> suspending device is registered concurrently with its ->suspend()
> callback.  In that case, since the new device (the child) is added
> to dpm_active after its parent, the PM core will attempt to
> suspend it after the parent, which is wrong.
> 
> Introduce a new member of struct dev_pm_info, called 'sleeping',
> and use it to check if the parent of the device being added to
> dpm_active has been suspended, in which case the device registration
> fails.  Also, use 'sleeping' for checking if the ordering of devices
> on dpm_active is correct.
> 
> Introduce variable 'all_sleeping' that will be set to 'true' once all
> devices have been suspended and make new device registrations fail
> until 'all_sleeping' is reset to 'false', in order to avoid having
> unsuspended devices around while the system is going into a sleep state.
> 
> Remove pm_sleep_rwsem which is not necessary any more.
> 
> Special thanks to Alan Stern for discussions and suggestions that
> lead to the creation of this patch.
> 
> Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>

ACK.

-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

Re: [PATCH 2/3] Driver core: Call device_pm_add() after bus_add_device() in device_add()

[Pavel Machek]

On Wed 2008-03-12 00:59:38, Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rjw@sisk.pl>
> 
> Include dpm_sysfs_add() into device_pm_add(), in analogy with
> device_pm_remove(), and modify device_add() to call the latter after
> bus_add_device(), to avoid situations in which the PM core may
> attempt to suspend a device the registration of which has not been
> successful.
> 
> Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>

ACK.

-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

Re: [PATCH 3/3] PM: make wakeup flags available whenever CONFIG_PM is set

[Pavel Machek]

On Wed 2008-03-12 01:01:47, Rafael J. Wysocki wrote:
> From: Alan Stern <stern@rowland.harvard.edu>
> 
> The various wakeup flags and their accessor macros in struct
> dev_pm_info should be available whenever CONFIG_PM is enabled, not
> just when CONFIG_PM_SLEEP is on.  Otherwise remote wakeup won't always
> be configurable for runtime power management.  This patch (as1056)
> fixes the oversight.
> 
> [rjw: rebased the patch on top of the previous two.]
> 
> Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
> CC: David Brownell <david-b@pacbell.net>
> Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>

ACK. But I wonder if we should reduce ammount of config options we
have in power management. All those combinations are hard to test...
									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

patch driver-core-call-device_pm_add-after-bus_add_device-in-device_add.patch added to gregkh-2.6 tree

[gregkh]

This is a note to let you know that I've just added the patch titled

     Subject: Driver core: Call device_pm_add() after bus_add_device() in device_add()

to my gregkh-2.6 tree.  Its filename is

     driver-core-call-device_pm_add-after-bus_add_device-in-device_add.patch

This tree can be found at 
    http://www.kernel.org/pub/linux/kernel/people/gregkh/gregkh-2.6/patches/


>From rjw@sisk.pl  Thu Mar 13 13:45:38 2008
From: "Rafael J. Wysocki" <rjw@sisk.pl>
Date: Wed, 12 Mar 2008 00:59:38 +0100
Subject: Driver core: Call device_pm_add() after bus_add_device() in device_add()
To: Greg KH <greg@kroah.com>
Cc: Alan Stern <stern@rowland.harvard.edu>, Andrew Morton <akpm@linux-foundation.org>, David Brownell <david-b@pacbell.net>, LKML <linux-kernel@vger.kernel.org>, Pavel Machek <pavel@ucw.cz>, pm list <linux-pm@lists.linux-foundation.org>
Message-ID: <200803120059.39902.rjw@sisk.pl>
Content-Disposition: inline


From: Rafael J. Wysocki <rjw@sisk.pl>

Include dpm_sysfs_add() into device_pm_add(), in analogy with
device_pm_remove(), and modify device_add() to call the latter after
bus_add_device(), to avoid situations in which the PM core may
attempt to suspend a device the registration of which has not been
successful.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
 drivers/base/core.c       |   15 +++++----------
 drivers/base/power/main.c |    4 +++-
 2 files changed, 8 insertions(+), 11 deletions(-)

--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -818,17 +818,12 @@ int device_add(struct device *dev)
 	error = device_add_attrs(dev);
 	if (error)
 		goto AttrsError;
-	error = dpm_sysfs_add(dev);
-	if (error)
-		goto PMError;
-	error = device_pm_add(dev);
-	if (error) {
-		dpm_sysfs_remove(dev);
-		goto PMError;
-	}
 	error = bus_add_device(dev);
 	if (error)
 		goto BusError;
+	error = device_pm_add(dev);
+	if (error)
+		goto PMError;
 	kobject_uevent(&dev->kobj, KOBJ_ADD);
 	bus_attach_device(dev);
 	if (parent)
@@ -848,9 +843,9 @@ int device_add(struct device *dev)
  Done:
 	put_device(dev);
 	return error;
- BusError:
-	device_pm_remove(dev);
  PMError:
+	bus_remove_device(dev);
+ BusError:
 	if (dev->bus)
 		blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
 					     BUS_NOTIFY_DEL_DEVICE, dev);
--- a/drivers/base/power/main.c
+++ b/drivers/base/power/main.c
@@ -81,7 +81,9 @@ int device_pm_add(struct device *dev)
 		WARN_ON(true);
 		error = -EBUSY;
 	} else {
-		list_add_tail(&dev->power.entry, &dpm_active);
+		error = dpm_sysfs_add(dev);
+		if (!error)
+			list_add_tail(&dev->power.entry, &dpm_active);
 	}
 	mutex_unlock(&dpm_list_mtx);
 	return error;


Patches currently in gregkh-2.6 which might be from rjw@sisk.pl are

driver-core/power_state-remove-it-from-driver-core.patch
driver-core/pm-handle-device-registrations-during-suspend-resume.patch
driver-core/pm-make-wakeup-flags-available-whenever-config_pm-is-set.patch
driver-core/driver-core-call-device_pm_add-after-bus_add_device-in-device_add.patch

patch pm-handle-device-registrations-during-suspend-resume.patch added to gregkh-2.6 tree

[gregkh]

This is a note to let you know that I've just added the patch titled

     Subject: PM: Handle device registrations during suspend/resume

to my gregkh-2.6 tree.  Its filename is

     pm-handle-device-registrations-during-suspend-resume.patch

This tree can be found at 
    http://www.kernel.org/pub/linux/kernel/people/gregkh/gregkh-2.6/patches/


>From rjw@sisk.pl  Thu Mar 13 13:44:50 2008
From: "Rafael J. Wysocki" <rjw@sisk.pl>
Date: Wed, 12 Mar 2008 00:57:22 +0100
Subject: PM: Handle device registrations during suspend/resume
To: Greg KH <greg@kroah.com>
Cc: Alan Stern <stern@rowland.harvard.edu>, Andrew Morton <akpm@linux-foundation.org>, David Brownell <david-b@pacbell.net>, LKML <linux-kernel@vger.kernel.org>, Pavel Machek <pavel@ucw.cz>, pm list <linux-pm@lists.linux-foundation.org>
Message-ID: <200803120057.23101.rjw@sisk.pl>
Content-Disposition: inline


From: Rafael J. Wysocki <rjw@sisk.pl>

Modify the PM core to protect its data structures, specifically the
dpm_active list, from being corrupted if a child of the currently
suspending device is registered concurrently with its ->suspend()
callback.  In that case, since the new device (the child) is added
to dpm_active after its parent, the PM core will attempt to
suspend it after the parent, which is wrong.

Introduce a new member of struct dev_pm_info, called 'sleeping',
and use it to check if the parent of the device being added to
dpm_active has been suspended, in which case the device registration
fails.  Also, use 'sleeping' for checking if the ordering of devices
on dpm_active is correct.

Introduce variable 'all_sleeping' that will be set to 'true' once all
devices have been suspended and make new device registrations fail
until 'all_sleeping' is reset to 'false', in order to avoid having
unsuspended devices around while the system is going into a sleep state.

Remove pm_sleep_rwsem which is not necessary any more.

Special thanks to Alan Stern for discussions and suggestions that
lead to the creation of this patch.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
 Documentation/power/devices.txt |    5 +++
 drivers/base/core.c             |    6 +++-
 drivers/base/power/main.c       |   57 ++++++++++++++++++----------------------
 drivers/base/power/power.h      |   23 ++--------------
 include/linux/pm.h              |    1 
 5 files changed, 40 insertions(+), 52 deletions(-)

--- a/Documentation/power/devices.txt
+++ b/Documentation/power/devices.txt
@@ -196,6 +196,11 @@ its parent; and can't be removed or susp
 
 The policy is that the device tree should match hardware bus topology.
 (Or at least the control bus, for devices which use multiple busses.)
+In particular, this means that a device registration may fail if the parent of
+the device is suspending (ie. has been chosen by the PM core as the next
+device to suspend) or has already suspended, as well as after all of the other
+devices have been suspended.  Device drivers must be prepared to cope with such
+situations.
 
 
 Suspending Devices
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -821,7 +821,11 @@ int device_add(struct device *dev)
 	error = dpm_sysfs_add(dev);
 	if (error)
 		goto PMError;
-	device_pm_add(dev);
+	error = device_pm_add(dev);
+	if (error) {
+		dpm_sysfs_remove(dev);
+		goto PMError;
+	}
 	error = bus_add_device(dev);
 	if (error)
 		goto BusError;
--- a/drivers/base/power/main.c
+++ b/drivers/base/power/main.c
@@ -54,7 +54,8 @@ static LIST_HEAD(dpm_destroy);
 
 static DEFINE_MUTEX(dpm_list_mtx);
 
-static DECLARE_RWSEM(pm_sleep_rwsem);
+/* 'true' if all devices have been suspended, protected by dpm_list_mtx */
+static bool all_sleeping;
 
 int (*platform_enable_wakeup)(struct device *dev, int is_on);
 
@@ -62,14 +63,28 @@ int (*platform_enable_wakeup)(struct dev
  *	device_pm_add - add a device to the list of active devices
  *	@dev:	Device to be added to the list
  */
-void device_pm_add(struct device *dev)
+int device_pm_add(struct device *dev)
 {
+	int error = 0;
+
 	pr_debug("PM: Adding info for %s:%s\n",
 		 dev->bus ? dev->bus->name : "No Bus",
 		 kobject_name(&dev->kobj));
 	mutex_lock(&dpm_list_mtx);
-	list_add_tail(&dev->power.entry, &dpm_active);
+	if ((dev->parent && dev->parent->power.sleeping) || all_sleeping) {
+		if (dev->parent->power.sleeping)
+			dev_warn(dev,
+				"parent %s is sleeping, will not add\n",
+				dev->parent->bus_id);
+		else
+			dev_warn(dev, "devices are sleeping, will not add\n");
+		WARN_ON(true);
+		error = -EBUSY;
+	} else {
+		list_add_tail(&dev->power.entry, &dpm_active);
+	}
 	mutex_unlock(&dpm_list_mtx);
+	return error;
 }
 
 /**
@@ -107,32 +122,6 @@ void device_pm_schedule_removal(struct d
 }
 EXPORT_SYMBOL_GPL(device_pm_schedule_removal);
 
-/**
- *	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 -------------------------*/
 
 /**
@@ -242,11 +231,13 @@ static int resume_device(struct device *
 static void dpm_resume(void)
 {
 	mutex_lock(&dpm_list_mtx);
+	all_sleeping = false;
 	while(!list_empty(&dpm_off)) {
 		struct list_head *entry = dpm_off.next;
 		struct device *dev = to_device(entry);
 
 		list_move_tail(entry, &dpm_active);
+		dev->power.sleeping = false;
 		mutex_unlock(&dpm_list_mtx);
 		resume_device(dev);
 		mutex_lock(&dpm_list_mtx);
@@ -285,7 +276,6 @@ void device_resume(void)
 	might_sleep();
 	dpm_resume();
 	unregister_dropped_devices();
-	up_write(&pm_sleep_rwsem);
 }
 EXPORT_SYMBOL_GPL(device_resume);
 
@@ -421,6 +411,9 @@ static int dpm_suspend(pm_message_t stat
 		struct list_head *entry = dpm_active.prev;
 		struct device *dev = to_device(entry);
 
+		WARN_ON(dev->parent && dev->parent->power.sleeping);
+
+		dev->power.sleeping = true;
 		mutex_unlock(&dpm_list_mtx);
 		error = suspend_device(dev, state);
 		mutex_lock(&dpm_list_mtx);
@@ -432,11 +425,14 @@ static int dpm_suspend(pm_message_t stat
 					(error == -EAGAIN ?
 					" (please convert to suspend_late)" :
 					""));
+			dev->power.sleeping = false;
 			break;
 		}
 		if (!list_empty(&dev->power.entry))
 			list_move(&dev->power.entry, &dpm_off);
 	}
+	if (!error)
+		all_sleeping = true;
 	mutex_unlock(&dpm_list_mtx);
 
 	return error;
@@ -454,7 +450,6 @@ int device_suspend(pm_message_t state)
 	int error;
 
 	might_sleep();
-	down_write(&pm_sleep_rwsem);
 	error = dpm_suspend(state);
 	if (error)
 		device_resume();
--- a/drivers/base/power/power.h
+++ b/drivers/base/power/power.h
@@ -11,30 +11,13 @@ static inline struct device *to_device(s
 	return container_of(entry, struct device, power.entry);
 }
 
-extern void device_pm_add(struct device *);
+extern int device_pm_add(struct device *);
 extern void device_pm_remove(struct device *);
-extern int pm_sleep_lock(void);
-extern void pm_sleep_unlock(void);
 
 #else /* CONFIG_PM_SLEEP */
 
-
-static inline void device_pm_add(struct device *dev)
-{
-}
-
-static inline void device_pm_remove(struct device *dev)
-{
-}
-
-static inline int pm_sleep_lock(void)
-{
-	return 0;
-}
-
-static inline void pm_sleep_unlock(void)
-{
-}
+static inline int device_pm_add(struct device *dev) { return 0; }
+static inline void device_pm_remove(struct device *dev) {}
 
 #endif
 
--- a/include/linux/pm.h
+++ b/include/linux/pm.h
@@ -183,6 +183,7 @@ typedef struct pm_message {
 struct dev_pm_info {
 	pm_message_t		power_state;
 	unsigned		can_wakeup:1;
+	bool			sleeping:1;	/* Owned by the PM core */
 #ifdef	CONFIG_PM_SLEEP
 	unsigned		should_wakeup:1;
 	struct list_head	entry;


Patches currently in gregkh-2.6 which might be from rjw@sisk.pl are

driver-core/power_state-remove-it-from-driver-core.patch
driver-core/pm-handle-device-registrations-during-suspend-resume.patch
driver-core/pm-make-wakeup-flags-available-whenever-config_pm-is-set.patch
driver-core/driver-core-call-device_pm_add-after-bus_add_device-in-device_add.patch

patch pm-make-wakeup-flags-available-whenever-config_pm-is-set.patch added to gregkh-2.6 tree

[gregkh]

This is a note to let you know that I've just added the patch titled

     Subject: PM: make wakeup flags available whenever CONFIG_PM is set

to my gregkh-2.6 tree.  Its filename is

     pm-make-wakeup-flags-available-whenever-config_pm-is-set.patch

This tree can be found at 
    http://www.kernel.org/pub/linux/kernel/people/gregkh/gregkh-2.6/patches/


>From rjw@sisk.pl  Thu Mar 13 13:46:04 2008
From: Alan Stern <stern@rowland.harvard.edu>
Date: Wed, 12 Mar 2008 01:01:47 +0100
Subject: PM: make wakeup flags available whenever CONFIG_PM is set
To: Greg KH <greg@kroah.com>
Cc: Alan Stern <stern@rowland.harvard.edu>, Andrew Morton <akpm@linux-foundation.org>, David Brownell <david-b@pacbell.net>, LKML <linux-kernel@vger.kernel.org>, Pavel Machek <pavel@ucw.cz>, pm list <linux-pm@lists.linux-foundation.org>
Message-ID: <200803120101.48805.rjw@sisk.pl>
Content-Disposition: inline

From: Alan Stern <stern@rowland.harvard.edu>

The various wakeup flags and their accessor macros in struct
dev_pm_info should be available whenever CONFIG_PM is enabled, not
just when CONFIG_PM_SLEEP is on.  Otherwise remote wakeup won't always
be configurable for runtime power management.  This patch (as1056)
fixes the oversight.

[rjw: rebased the patch on top of the previous two.]

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
CC: David Brownell <david-b@pacbell.net>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
 drivers/base/power/main.c  |    2 -
 drivers/base/power/sysfs.c |    2 +
 include/linux/pm.h         |   64 +++++++++++++++++++++++++--------------------
 3 files changed, 38 insertions(+), 30 deletions(-)

--- a/drivers/base/power/main.c
+++ b/drivers/base/power/main.c
@@ -57,8 +57,6 @@ static DEFINE_MUTEX(dpm_list_mtx);
 /* 'true' if all devices have been suspended, protected by dpm_list_mtx */
 static bool all_sleeping;
 
-int (*platform_enable_wakeup)(struct device *dev, int is_on);
-
 /**
  *	device_pm_add - add a device to the list of active devices
  *	@dev:	Device to be added to the list
--- a/drivers/base/power/sysfs.c
+++ b/drivers/base/power/sysfs.c
@@ -6,6 +6,8 @@
 #include <linux/string.h>
 #include "power.h"
 
+int (*platform_enable_wakeup)(struct device *dev, int is_on);
+
 
 /*
  *	wakeup - Report/change current wakeup option for device
--- a/include/linux/pm.h
+++ b/include/linux/pm.h
@@ -183,9 +183,9 @@ typedef struct pm_message {
 struct dev_pm_info {
 	pm_message_t		power_state;
 	unsigned		can_wakeup:1;
+	unsigned		should_wakeup:1;
 	bool			sleeping:1;	/* Owned by the PM core */
 #ifdef	CONFIG_PM_SLEEP
-	unsigned		should_wakeup:1;
 	struct list_head	entry;
 #endif
 };
@@ -198,11 +198,6 @@ extern void device_resume(void);
 extern int device_suspend(pm_message_t state);
 extern int device_prepare_suspend(pm_message_t state);
 
-#define device_set_wakeup_enable(dev,val) \
-	((dev)->power.should_wakeup = !!(val))
-#define device_may_wakeup(dev) \
-	(device_can_wakeup(dev) && (dev)->power.should_wakeup)
-
 extern void __suspend_report_result(const char *function, void *fn, int ret);
 
 #define suspend_report_result(fn, ret)					\
@@ -210,6 +205,35 @@ extern void __suspend_report_result(cons
 		__suspend_report_result(__FUNCTION__, fn, ret);		\
 	} while (0)
 
+#else /* !CONFIG_PM_SLEEP */
+
+static inline int device_suspend(pm_message_t state)
+{
+	return 0;
+}
+
+#define suspend_report_result(fn, ret) 		do {} while (0)
+
+#endif /* !CONFIG_PM_SLEEP */
+
+#ifdef CONFIG_PM
+
+/* changes to device_may_wakeup take effect on the next pm state change.
+ * by default, devices should wakeup if they can.
+ */
+#define device_can_wakeup(dev) \
+	((dev)->power.can_wakeup)
+#define device_init_wakeup(dev,val) \
+	do { \
+		device_can_wakeup(dev) = !!(val); \
+		device_set_wakeup_enable(dev,val); \
+	} while(0)
+
+#define device_set_wakeup_enable(dev,val) \
+	((dev)->power.should_wakeup = !!(val))
+#define device_may_wakeup(dev) \
+	(device_can_wakeup(dev) && (dev)->power.should_wakeup)
+
 /*
  * Platform hook to activate device wakeup capability, if that's not already
  * handled by enable_irq_wake() etc.
@@ -224,35 +248,19 @@ static inline int call_platform_enable_w
 	return 0;
 }
 
-#else /* !CONFIG_PM_SLEEP */
-
-static inline int device_suspend(pm_message_t state)
-{
-	return 0;
-}
-
-#define device_set_wakeup_enable(dev,val)	do{}while(0)
-#define device_may_wakeup(dev)			(0)
+#else /* !CONFIG_PM */
 
-#define suspend_report_result(fn, ret) do { } while (0)
+#define device_can_wakeup(dev)			0
+#define device_init_wakeup(dev,val)		do {} while (0)
+#define device_set_wakeup_enable(dev,val)	do {} while (0)
+#define device_may_wakeup(dev)			0
 
 static inline int call_platform_enable_wakeup(struct device *dev, int is_on)
 {
 	return 0;
 }
 
-#endif /* !CONFIG_PM_SLEEP */
-
-/* changes to device_may_wakeup take effect on the next pm state change.
- * by default, devices should wakeup if they can.
- */
-#define device_can_wakeup(dev) \
-	((dev)->power.can_wakeup)
-#define device_init_wakeup(dev,val) \
-	do { \
-		device_can_wakeup(dev) = !!(val); \
-		device_set_wakeup_enable(dev,val); \
-	} while(0)
+#endif /* !CONFIG_PM */
 
 /*
  * Global Power Management flags


Patches currently in gregkh-2.6 which might be from stern@rowland.harvard.edu are

usb/usb-convert-usb.h-struct-usb_device-to-kernel-doc.patch
usb/usb-make-usb_storage_onetouch-available-with-pm.patch
usb/usb-usb-ohci-sm501-driver-use-the-conventional-convention-for-suspend-and-resume.patch
usb/usb-reorganize-code-in-hub.c.patch
usb/usb-ehci-carry-out-port-handover-during-each-root-hub-resume.patch
usb/usb-new-quirk-flag-to-avoid-set-interface.patch
usb/drivers-usb-core-devio.c-suppress-warning-with-64k-page_size.patch
usb/usb-make-usb-persist-work-after-every-system-sleep.patch
usb/usb-remove-config_usb_persist-setting.patch
usb/usb-check-serial-number-string-after-device-reset.patch
usb/usb-enable-usb-persist-by-default.patch
usb/usb-remove-dev-power.power_state.patch
driver-core/pm-handle-device-registrations-during-suspend-resume.patch
driver-core/pm-make-wakeup-flags-available-whenever-config_pm-is-set.patch
driver-core/driver-core-call-device_pm_add-after-bus_add_device-in-device_add.patch