The patch titled
PM: Handle device registrations during suspend/resume
has been removed from the -mm tree. Its filename was
pm-handle-device-registrations-during-suspend-resume.patch
This patch was dropped because it was merged into mainline or a subsystem tree
The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/
------------------------------------------------------
Subject: PM: Handle device registrations during suspend/resume
From: Rafael J. Wysocki <rjw@xxxxxxx>
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@xxxxxxx>
Cc: Greg KH <greg@xxxxxxxxx>
Cc: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
Cc: David Brownell <david-b@xxxxxxxxxxx>
Cc: Pavel Machek <pavel@xxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
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(-)
diff -puN Documentation/power/devices.txt~pm-handle-device-registrations-during-suspend-resume Documentation/power/devices.txt
--- a/Documentation/power/devices.txt~pm-handle-device-registrations-during-suspend-resume
+++ a/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
diff -puN drivers/base/core.c~pm-handle-device-registrations-during-suspend-resume drivers/base/core.c
--- a/drivers/base/core.c~pm-handle-device-registrations-during-suspend-resume
+++ a/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;
diff -puN drivers/base/power/main.c~pm-handle-device-registrations-during-suspend-resume drivers/base/power/main.c
--- a/drivers/base/power/main.c~pm-handle-device-registrations-during-suspend-resume
+++ a/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();
diff -puN drivers/base/power/power.h~pm-handle-device-registrations-during-suspend-resume drivers/base/power/power.h
--- a/drivers/base/power/power.h~pm-handle-device-registrations-during-suspend-resume
+++ a/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
diff -puN include/linux/pm.h~pm-handle-device-registrations-during-suspend-resume include/linux/pm.h
--- a/include/linux/pm.h~pm-handle-device-registrations-during-suspend-resume
+++ a/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 -mm which might be from rjw@xxxxxxx are
git-acpi.patch
pm-remove-legacy-pm.patch
mips-alchemy-crapectomy-after-removal-of-pm_send_all-calls.patch
pm-make-wakeup-flags-available-whenever-config_pm-is-set-checkpatch-fixes.patch
x86-fix-aperture-vs-suspend-problem.patch
x86-fix-aperture-vs-suspend-problem-checkpatch-fixes.patch
revert-pcie-utilize-pcie-transaction-pending-bit.patch
power-replace-remaining-__function__-occurrences.patch
pm-gxfb-add-hook-to-pm-console-layer-that-allows-disabling-of-suspend-vt-switch.patch
shrink_slab-handle-bad-shrinkers.patch
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