14 files changed, 375 insertions, 10 deletions

diff --git a/Documentation/ABI/testing/sysfs-power b/Documentation/ABI/testing/sysfs-power
index d6a801f45b48..2875f1f74a07 100644
--- a/Documentation/ABI/testing/sysfs-power
+++ b/Documentation/ABI/testing/sysfs-power
@@ -114,3 +114,18 @@ 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 put the
+                system into a sleep state while taking into account the
+                concurrent arrival of wakeup events.  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.
diff --git a/drivers/base/power/Makefile b/drivers/base/power/Makefile
index 89de75325cea..cbccf9a3cee4 100644
--- a/drivers/base/power/Makefile
+++ b/drivers/base/power/Makefile
@@ -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
diff --git a/drivers/base/power/main.c b/drivers/base/power/main.c
index 941fcb87e52a..5419a49ff135 100644
--- a/drivers/base/power/main.c
+++ b/drivers/base/power/main.c
@@ -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);
 }
 
diff --git a/drivers/base/power/sysfs.c b/drivers/base/power/sysfs.c
index a4c33bc51257..81d344e0e95d 100644
--- a/drivers/base/power/sysfs.c
+++ b/drivers/base/power/sysfs.c
@@ -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 +146,16 @@ wake_store(struct device * dev, struct device_attribute *attr,
 
 static DEVICE_ATTR(wakeup, 0644, wake_show, wake_store);
 
+#ifdef CONFIG_PM_SLEEP
+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);
+#endif
+
 #ifdef CONFIG_PM_ADVANCED_DEBUG
 #ifdef CONFIG_PM_RUNTIME
 
@@ -230,6 +242,9 @@ static struct attribute * power_attrs[] = {
         &dev_attr_control.attr,
 #endif
         &dev_attr_wakeup.attr,
+#ifdef CONFIG_PM_SLEEP
+        &dev_attr_wakeup_count.attr,
+#endif
 #ifdef CONFIG_PM_ADVANCED_DEBUG
         &dev_attr_async.attr,
 #ifdef CONFIG_PM_RUNTIME
diff --git a/drivers/base/power/wakeup.c b/drivers/base/power/wakeup.c
new file mode 100644
index 000000000000..25599077c39c
--- /dev/null
+++ b/drivers/base/power/wakeup.c
@@ -0,0 +1,229 @@
+/*
+ * 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);
+
+/*
+ * 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) {
+                events_in_progress--;
+                event_count++;
+        }
+        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;
+
+        while (events_in_progress && !signal_pending(current)) {
+                spin_unlock_irq(&events_lock);
+
+                schedule_timeout_interruptible(msecs_to_jiffies(100));
+
+                spin_lock_irq(&events_lock);
+        }
+        *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;
+}
diff --git a/drivers/pci/pci-acpi.c b/drivers/pci/pci-acpi.c
index 2e7a3bf13824..1ab98bbe58dd 100644
--- a/drivers/pci/pci-acpi.c
+++ b/drivers/pci/pci-acpi.c
@@ -48,6 +48,7 @@ static void pci_acpi_wake_dev(acpi_handle handle, u32 event, void *context)
         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);
         }
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 740fb4ea9669..130ed1daf0f8 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -1275,6 +1275,22 @@ bool pci_check_pme_status(struct pci_dev *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 *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;
 }
 
diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
index f8077b3c8c8c..c8b7fd056ccd 100644
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -56,6 +56,7 @@ extern void pci_update_current_state(struct pci_dev *dev, pci_power_t state);
 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);
diff --git a/drivers/pci/pcie/pme/pcie_pme.c b/drivers/pci/pcie/pme/pcie_pme.c
index d672a0a63816..bbdea18693d9 100644
--- a/drivers/pci/pcie/pme/pcie_pme.c
+++ b/drivers/pci/pcie/pme/pcie_pme.c
@@ -154,6 +154,7 @@ static bool pcie_pme_walk_bus(struct pci_bus *bus)
                 /* 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(struct pci_dev *port, u16 req_id)
         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) {
                 /*
diff --git a/include/linux/pm.h b/include/linux/pm.h
index 8e258c727971..b417fc46f3fc 100644
--- a/include/linux/pm.h
+++ b/include/linux/pm.h
@@ -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(const char *function, void *fn, int ret);
         } 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_message_t state)
 #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() */
diff --git a/include/linux/suspend.h b/include/linux/suspend.h
index bc7d6bb4cd8e..bf1bab7b059c 100644
--- a/include/linux/suspend.h
+++ b/include/linux/suspend.h
@@ -286,6 +286,13 @@ extern int unregister_pm_notifier(struct notifier_block *nb);
                 { .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)
diff --git a/kernel/power/hibernate.c b/kernel/power/hibernate.c
index aa9e916da4d5..f61202916631 100644
--- a/kernel/power/hibernate.c
+++ b/kernel/power/hibernate.c
@@ -277,7 +277,7 @@ static int create_image(int platform_mode)
                 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_mode)
                         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();
 
diff --git a/kernel/power/main.c b/kernel/power/main.c
index b58800b21fc0..62b0bc6e4983 100644
--- a/kernel/power/main.c
+++ b/kernel/power/main.c
@@ -204,6 +204,60 @@ static ssize_t state_store(struct kobject *kobj, struct kobj_attribute *attr,
 
 power_attr(state);
 
+#ifdef CONFIG_PM_SLEEP
+/*
+ * 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);
+#endif /* CONFIG_PM_SLEEP */
+
 #ifdef CONFIG_PM_TRACE
 int pm_trace_enabled;
 
@@ -236,6 +290,7 @@ 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
diff --git a/kernel/power/suspend.c b/kernel/power/suspend.c
index f37cb7dd4402..5f8d09f94325 100644
--- a/kernel/power/suspend.c
+++ b/kernel/power/suspend.c
@@ -163,8 +163,10 @@ static int suspend_enter(suspend_state_t state)
 
         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();
         }