===================================================================
@@ -204,6 +204,58 @@ static ssize_t state_store(struct kobjec
power_attr(state);
+/*
+ * The 'wakeup_count' attribute, along with the functions defined in
+ * drivers/base/power/wakeup.c, provides a means by which wakeup events can be
+ * handled in a non-racy way.
+ *
+ * If a wakeup event occurs when the system is in a sleep state, it simply is
+ * woken up. In turn, if an event that would wake the system up from a sleep
+ * state occurs when it is undergoing a transition to that sleep state, the
+ * transition should be aborted. Moreover, if such an event occurs when the
+ * system is in the working state, an attempt to start a transition to the
+ * given sleep state should fail during certain period after the detection of
+ * the event. Using the 'state' attribute alone is not sufficient to satisfy
+ * these requirements, because a wakeup event may occur exactly when 'state'
+ * is being written to and may be delivered to user space right before it is
+ * frozen, so the event will remain only partially processed until the system is
+ * woken up by another event. In particular, it won't cause the transition to
+ * a sleep state to be aborted.
+ *
+ * This difficulty may be overcome if user space uses 'wakeup_count' before
+ * writing to 'state'. It first should read from 'wakeup_count' and store
+ * the read value. Then, after carrying out its own preparations for the system
+ * transition to a sleep state, it should write the stored value to
+ * 'wakeup_count'. If that fails, at least one wakeup event has occured since
+ * 'wakeup_count' was read and 'state' should not be written to. Otherwise, it
+ * is allowed to write to 'state', but the transition will be aborted if there
+ * are any wakeup events detected after 'wakeup_count' was written to.
+ */
+
+static ssize_t wakeup_count_show(struct kobject *kobj,
+ struct kobj_attribute *attr,
+ char *buf)
+{
+ unsigned long val;
+
+ return pm_get_wakeup_count(&val) ? sprintf(buf, "%lu\n", val) : -EINTR;
+}
+
+static ssize_t wakeup_count_store(struct kobject *kobj,
+ struct kobj_attribute *attr,
+ const char *buf, size_t n)
+{
+ unsigned long val;
+
+ if (sscanf(buf, "%lu", &val) == 1) {
+ if (pm_save_wakeup_count(val))
+ return n;
+ }
+ return -EINVAL;
+}
+
+power_attr(wakeup_count);
+
#ifdef CONFIG_PM_TRACE
int pm_trace_enabled;
@@ -236,6 +288,7 @@ static struct attribute * g[] = {
#endif
#ifdef CONFIG_PM_SLEEP
&pm_async_attr.attr,
+ &wakeup_count_attr.attr,
#ifdef CONFIG_PM_DEBUG
&pm_test_attr.attr,
#endif
===================================================================
@@ -0,0 +1,240 @@
+/*
+ * drivers/base/power/wakeup.c - System wakeup events framework
+ *
+ * Copyright (c) 2010 Rafael J. Wysocki <rjw@sisk.pl>, Novell Inc.
+ *
+ * This file is released under the GPLv2.
+ */
+
+#include <linux/device.h>
+#include <linux/slab.h>
+#include <linux/sched.h>
+#include <linux/capability.h>
+#include <linux/suspend.h>
+#include <linux/pm.h>
+
+/*
+ * If set, the suspend/hibernate code will abort transitions to a sleep state
+ * if wakeup events are registered during or immediately before the transition.
+ */
+bool events_check_enabled;
+
+/* The counter of registered wakeup events. */
+static unsigned long event_count;
+/* A preserved old value of event_count. */
+static unsigned long saved_event_count;
+/* The counter of wakeup events being processed. */
+static unsigned long events_in_progress;
+
+static DEFINE_SPINLOCK(events_lock);
+static DECLARE_WAIT_QUEUE_HEAD(events_wait_queue);
+
+/*
+ * The functions below use the observation that each wakeup event starts a
+ * period in which the system should not be suspended. The moment this period
+ * will end depends on how the wakeup event is going to be processed after being
+ * detected and all of the possible cases can be divided into two distinct
+ * groups.
+ *
+ * First, a wakeup event may be detected by the same functional unit that will
+ * carry out the entire processing of it and possibly will pass it to user space
+ * for further processing. In that case the functional unit that has detected
+ * the event may later "close" the "no suspend" period associated with it
+ * directly as soon as it has been dealt with. The pair of pm_stay_awake() and
+ * pm_relax(), balanced with each other, is supposed to be used in such
+ * situations.
+ *
+ * Second, a wakeup event may be detected by one functional unit and processed
+ * by another one. In that case the unit that has detected it cannot really
+ * "close" the "no suspend" period associated with it, unless it knows in
+ * advance what's going to happen to the event during processing. This
+ * knowledge, however, may not be available to it, so it can simply specify time
+ * to wait before the system can be suspended and pass it as the second
+ * argument of pm_wakeup_event().
+ */
+
+/**
+ * pm_stay_awake - Notify the PM core that a wakeup event is being processed.
+ * @dev: Device the wakeup event is related to.
+ *
+ * Notify the PM core of a wakeup event (signaled by @dev) by incrementing the
+ * counter of wakeup events being processed. If @dev is not NULL, the counter
+ * of wakeup events related to @dev is incremented too.
+ *
+ * Call this function after detecting of a wakeup event if pm_relax() is going
+ * to be called directly after processing the event (and possibly passing it to
+ * user space for further processing).
+ *
+ * It is safe to call this function from interrupt context.
+ */
+void pm_stay_awake(struct device *dev)
+{
+ unsigned long flags;
+
+ spin_lock_irqsave(&events_lock, flags);
+ if (dev)
+ dev->power.wakeup_count++;
+
+ events_in_progress++;
+ spin_unlock_irqrestore(&events_lock, flags);
+}
+
+/**
+ * pm_relax - Notify the PM core that processing of a wakeup event has ended.
+ *
+ * Notify the PM core that a wakeup event has been processed by decrementing
+ * the counter of wakeup events being processed and incrementing the counter
+ * of registered wakeup events.
+ *
+ * Call this function for wakeup events whose processing started with calling
+ * pm_stay_awake().
+ *
+ * It is safe to call it from interrupt context.
+ */
+void pm_relax(void)
+{
+ unsigned long flags;
+
+ spin_lock_irqsave(&events_lock, flags);
+ if (events_in_progress) {
+ event_count++;
+ if (!--events_in_progress)
+ wake_up_all(&events_wait_queue);
+ }
+ spin_unlock_irqrestore(&events_lock, flags);
+}
+
+/**
+ * pm_wakeup_work_fn - Deferred closing of a wakeup event.
+ *
+ * Execute pm_relax() for a wakeup event detected in the past and free the
+ * work item object used for queuing up the work.
+ */
+static void pm_wakeup_work_fn(struct work_struct *work)
+{
+ struct delayed_work *dwork = to_delayed_work(work);
+
+ pm_relax();
+ kfree(dwork);
+}
+
+/**
+ * pm_wakeup_event - Notify the PM core of a wakeup event.
+ * @dev: Device the wakeup event is related to.
+ * @msec: Anticipated event processing time (in milliseconds).
+ *
+ * Notify the PM core of a wakeup event (signaled by @dev) that will take
+ * approximately @msec milliseconds to be processed by the kernel. Increment
+ * the counter of wakeup events being processed and queue up a work item
+ * that will execute pm_relax() for the event after @msec milliseconds. If @dev
+ * is not NULL, the counter of wakeup events related to @dev is incremented too.
+ *
+ * It is safe to call this function from interrupt context.
+ */
+void pm_wakeup_event(struct device *dev, unsigned int msec)
+{
+ unsigned long flags;
+ struct delayed_work *dwork;
+
+ dwork = msec ? kzalloc(sizeof(*dwork), GFP_ATOMIC) : NULL;
+
+ spin_lock_irqsave(&events_lock, flags);
+ if (dev)
+ dev->power.wakeup_count++;
+
+ if (dwork) {
+ INIT_DELAYED_WORK(dwork, pm_wakeup_work_fn);
+ schedule_delayed_work(dwork, msecs_to_jiffies(msec));
+
+ events_in_progress++;
+ } else {
+ event_count++;
+ }
+ spin_unlock_irqrestore(&events_lock, flags);
+}
+
+/**
+ * pm_check_wakeup_events - Check for new wakeup events.
+ *
+ * Compare the current number of registered wakeup events with its preserved
+ * value from the past to check if new wakeup events have been registered since
+ * the old value was stored. Check if the current number of wakeup events being
+ * processed is zero.
+ */
+bool pm_check_wakeup_events(void)
+{
+ unsigned long flags;
+ bool ret = true;
+
+ spin_lock_irqsave(&events_lock, flags);
+ if (events_check_enabled) {
+ ret = (event_count == saved_event_count) && !events_in_progress;
+ events_check_enabled = ret;
+ }
+ spin_unlock_irqrestore(&events_lock, flags);
+ return ret;
+}
+
+/**
+ * pm_get_wakeup_count - Read the number of registered wakeup events.
+ * @count: Address to store the value at.
+ *
+ * Store the number of registered wakeup events at the address in @count. Block
+ * if the current number of wakeup events being processed is nonzero.
+ *
+ * Return false if the wait for the number of wakeup events being processed to
+ * drop down to zero has been interrupted by a signal (and the current number
+ * of wakeup events being processed is still nonzero). Otherwise return true.
+ */
+bool pm_get_wakeup_count(unsigned long *count)
+{
+ bool ret;
+
+ spin_lock_irq(&events_lock);
+ if (capable(CAP_SYS_ADMIN))
+ events_check_enabled = false;
+
+ if (events_in_progress) {
+ DEFINE_WAIT(wait);
+
+ do {
+ prepare_to_wait(&events_wait_queue, &wait,
+ TASK_INTERRUPTIBLE);
+ if (!events_in_progress)
+ break;
+ spin_unlock_irq(&events_lock);
+
+ schedule();
+
+ spin_lock_irq(&events_lock);
+ } while (!signal_pending(current));
+ finish_wait(&events_wait_queue, &wait);
+ }
+ *count = event_count;
+ ret = !events_in_progress;
+ spin_unlock_irq(&events_lock);
+ return ret;
+}
+
+/**
+ * pm_save_wakeup_count - Save the current number of registered wakeup events.
+ * @count: Value to compare with the current number of registered wakeup events.
+ *
+ * If @count is equal to the current number of registered wakeup events and the
+ * current number of wakeup events being processed is zero, store @count as the
+ * old number of registered wakeup events to be used by pm_check_wakeup_events()
+ * and return true. Otherwise return false.
+ */
+bool pm_save_wakeup_count(unsigned long count)
+{
+ bool ret = false;
+
+ spin_lock_irq(&events_lock);
+ if (count == event_count && !events_in_progress) {
+ saved_event_count = count;
+ events_check_enabled = true;
+ ret = true;
+ }
+ spin_unlock_irq(&events_lock);
+ return ret;
+}
===================================================================
@@ -457,6 +457,7 @@ struct dev_pm_info {
#ifdef CONFIG_PM_SLEEP
struct list_head entry;
struct completion completion;
+ unsigned long wakeup_count;
#endif
#ifdef CONFIG_PM_RUNTIME
struct timer_list suspend_timer;
@@ -552,6 +553,11 @@ extern void __suspend_report_result(cons
} while (0)
extern void device_pm_wait_for_dev(struct device *sub, struct device *dev);
+
+/* drivers/base/power/wakeup.c */
+extern void pm_wakeup_event(struct device *dev, unsigned int msec);
+extern void pm_stay_awake(struct device *dev);
+extern void pm_relax(void);
#else /* !CONFIG_PM_SLEEP */
#define device_pm_lock() do {} while (0)
@@ -565,6 +571,10 @@ static inline int dpm_suspend_start(pm_m
#define suspend_report_result(fn, ret) do {} while (0)
static inline void device_pm_wait_for_dev(struct device *a, struct device *b) {}
+
+static inline void pm_wakeup_event(struct device *dev, unsigned int msec) {}
+static inline void pm_stay_awake(struct device *dev) {}
+static inline void pm_relax(void) {}
#endif /* !CONFIG_PM_SLEEP */
/* How to reorder dpm_list after device_move() */
===================================================================
@@ -1,5 +1,5 @@
obj-$(CONFIG_PM) += sysfs.o
-obj-$(CONFIG_PM_SLEEP) += main.o
+obj-$(CONFIG_PM_SLEEP) += main.o wakeup.o
obj-$(CONFIG_PM_RUNTIME) += runtime.o
obj-$(CONFIG_PM_OPS) += generic_ops.o
obj-$(CONFIG_PM_TRACE_RTC) += trace.o
===================================================================
@@ -59,6 +59,7 @@ void device_pm_init(struct device *dev)
{
dev->power.status = DPM_ON;
init_completion(&dev->power.completion);
+ dev->power.wakeup_count = 0;
pm_runtime_init(dev);
}
===================================================================
@@ -172,8 +172,10 @@ static int suspend_enter(suspend_state_t
error = sysdev_suspend(PMSG_SUSPEND);
if (!error) {
- if (!suspend_test(TEST_CORE))
+ if (!suspend_test(TEST_CORE) && pm_check_wakeup_events()) {
error = suspend_ops->enter(state);
+ events_check_enabled = false;
+ }
sysdev_resume();
}
===================================================================
@@ -277,7 +277,7 @@ static int create_image(int platform_mod
goto Enable_irqs;
}
- if (hibernation_test(TEST_CORE))
+ if (hibernation_test(TEST_CORE) || !pm_check_wakeup_events())
goto Power_up;
in_suspend = 1;
@@ -288,8 +288,10 @@ static int create_image(int platform_mod
error);
/* Restore control flow magically appears here */
restore_processor_state();
- if (!in_suspend)
+ if (!in_suspend) {
+ events_check_enabled = false;
platform_leave(platform_mode);
+ }
Power_up:
sysdev_resume();
@@ -511,14 +513,20 @@ int hibernation_platform_enter(void)
local_irq_disable();
sysdev_suspend(PMSG_HIBERNATE);
+ if (!pm_check_wakeup_events()) {
+ error = -EAGAIN;
+ goto Power_up;
+ }
+
hibernation_ops->enter();
/* We should never get here */
while (1);
- /*
- * We don't need to reenable the nonboot CPUs or resume consoles, since
- * the system is going to be halted anyway.
- */
+ Power_up:
+ sysdev_resume();
+ local_irq_enable();
+ enable_nonboot_cpus();
+
Platform_finish:
hibernation_ops->finish();
===================================================================
@@ -48,6 +48,7 @@ static void pci_acpi_wake_dev(acpi_handl
if (event == ACPI_NOTIFY_DEVICE_WAKE && pci_dev) {
pci_check_pme_status(pci_dev);
pm_runtime_resume(&pci_dev->dev);
+ pci_wakeup_event(pci_dev);
if (pci_dev->subordinate)
pci_pme_wakeup_bus(pci_dev->subordinate);
}
===================================================================
@@ -154,6 +154,7 @@ static bool pcie_pme_walk_bus(struct pci
/* Skip PCIe devices in case we started from a root port. */
if (!pci_is_pcie(dev) && pci_check_pme_status(dev)) {
pm_request_resume(&dev->dev);
+ pci_wakeup_event(dev);
ret = true;
}
@@ -254,8 +255,10 @@ static void pcie_pme_handle_request(stru
if (found) {
/* The device is there, but we have to check its PME status. */
found = pci_check_pme_status(dev);
- if (found)
+ if (found) {
pm_request_resume(&dev->dev);
+ pci_wakeup_event(dev);
+ }
pci_dev_put(dev);
} else if (devfn) {
/*
===================================================================
@@ -73,6 +73,8 @@
* device are known to the PM core. However, for some devices this
* attribute is set to "enabled" by bus type code or device drivers and in
* that cases it should be safe to leave the default value.
+ *
+ * wakeup_count - Report the number of wakeup events related to the device
*/
static const char enabled[] = "enabled";
@@ -144,6 +146,14 @@ wake_store(struct device * dev, struct d
static DEVICE_ATTR(wakeup, 0644, wake_show, wake_store);
+static ssize_t wakeup_count_show(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ return sprintf(buf, "%lu\n", dev->power.wakeup_count);
+}
+
+static DEVICE_ATTR(wakeup_count, 0444, wakeup_count_show, NULL);
+
#ifdef CONFIG_PM_ADVANCED_DEBUG
#ifdef CONFIG_PM_RUNTIME
@@ -230,6 +240,7 @@ static struct attribute * power_attrs[]
&dev_attr_control.attr,
#endif
&dev_attr_wakeup.attr,
+ &dev_attr_wakeup_count.attr,
#ifdef CONFIG_PM_ADVANCED_DEBUG
&dev_attr_async.attr,
#ifdef CONFIG_PM_RUNTIME
===================================================================
@@ -56,6 +56,7 @@ extern void pci_update_current_state(str
extern void pci_disable_enabled_device(struct pci_dev *dev);
extern bool pci_check_pme_status(struct pci_dev *dev);
extern int pci_finish_runtime_suspend(struct pci_dev *dev);
+extern void pci_wakeup_event(struct pci_dev *dev);
extern int __pci_pme_wakeup(struct pci_dev *dev, void *ign);
extern void pci_pme_wakeup_bus(struct pci_bus *bus);
extern void pci_pm_init(struct pci_dev *dev);
===================================================================
@@ -1275,6 +1275,22 @@ bool pci_check_pme_status(struct pci_dev
return ret;
}
+/*
+ * Time to wait before the system can be put into a sleep state after reporting
+ * a wakeup event signaled by a PCI device.
+ */
+#define PCI_WAKEUP_COOLDOWN 100
+
+/**
+ * pci_wakeup_event - Report a wakeup event related to a given PCI device.
+ * @dev: Device to report the wakeup event for.
+ */
+void pci_wakeup_event(struct pci_dev *dev)
+{
+ if (device_may_wakeup(&dev->dev))
+ pm_wakeup_event(&dev->dev, PCI_WAKEUP_COOLDOWN);
+}
+
/**
* pci_pme_wakeup - Wake up a PCI device if its PME Status bit is set.
* @dev: Device to handle.
@@ -1285,8 +1301,10 @@ bool pci_check_pme_status(struct pci_dev
*/
static int pci_pme_wakeup(struct pci_dev *dev, void *ign)
{
- if (pci_check_pme_status(dev))
+ if (pci_check_pme_status(dev)) {
pm_request_resume(&dev->dev);
+ pci_wakeup_event(dev);
+ }
return 0;
}
===================================================================
@@ -295,6 +295,13 @@ extern int unregister_pm_notifier(struct
{ .notifier_call = fn, .priority = pri }; \
register_pm_notifier(&fn##_nb); \
}
+
+/* drivers/base/power/wakeup.c */
+extern bool events_check_enabled;
+
+extern bool pm_check_wakeup_events(void);
+extern bool pm_get_wakeup_count(unsigned long *count);
+extern bool pm_save_wakeup_count(unsigned long count);
#else /* !CONFIG_PM_SLEEP */
static inline int register_pm_notifier(struct notifier_block *nb)
===================================================================
@@ -114,3 +114,17 @@ Description:
if this file contains "1", which is the default. It may be
disabled by writing "0" to this file, in which case all devices
will be suspended and resumed synchronously.
+
+What: /sys/power/wakeup_count
+Date: July 2010
+Contact: Rafael J. Wysocki <rjw@sisk.pl>
+Description:
+ The /sys/power/wakeup_count file allows user space to avoid
+ losing wakeup events when transitioning the system into a sleep
+ state. Reading from it returns the current number of registered
+ wakeup events and it blocks if some wakeup events are being
+ processed at the time the file is read from. Writing to it
+ will only succeed if the current number of wakeup events is
+ equal to the written value and, if successful, will make the
+ kernel abort a subsequent transition to a sleep state if any
+ wakeup events are reported after the write has returned.