3 files changed, 72 insertions, 7 deletions

diff --git a/kernel/power/hibernate.c b/kernel/power/hibernate.c
index aa9e916da4d..f6120291663 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 b58800b21fc..62b0bc6e498 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 f37cb7dd440..5f8d09f9432 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();
 	}