[PATCH v5] PM / sleep: Mechanism to find source aborting kernel suspend transition

[Vimal Kumar <vimal.kumar32@gmail.com>]

Sometimes kernel suspend transitions can be aborted unconditionally by
manipulating pm_abort_suspend value using "hard" wakeup triggers or
through "pm_system_wakeup()".

There is no way to trace the source path of module or subsystem which
aborted the suspend transitions. This change will create a list of
wakeup sources aborting suspend in progress through "hard" events as
well as subsytems aborting suspend using "pm_system_wakeup()".

Example: Existing suspend failure logs:
[  349.708359] PM: Some devices failed to suspend, or early wake event detected
[  350.327842] PM: suspend exit

Suspend failure logs with this change:
[  518.761835] PM: Some devices failed to suspend, or early wake event detected
[  519.486939] PM: wakeup source or subsystem uart_suspend_port aborted suspend
[  519.500594] PM: suspend exit

Here we can clearly identify the module triggerring abort suspend.

Co-developed-by: Chinmoy Ghosh <chinmoyghosh2001@gmail.com>
Signed-off-by: Chinmoy Ghosh <chinmoyghosh2001@gmail.com>
Co-developed-by: Mintu Patel <mintupatel89@gmail.com>
Signed-off-by: Mintu Patel <mintupatel89@gmail.com>
Co-developed-by: Vishal Badole <badolevishal1116@gmail.com>
Signed-off-by: Vishal Badole <badolevishal1116@gmail.com>
Signed-off-by: Vimal Kumar <vimal.kumar32@gmail.com>
---
Changes in v5:
- Removed CONFIG_PM_DEBUG
- Moved conditional directives to .h file
- Used spin_lock instead of raw_spin_lock
---
 drivers/base/power/power.h  | 14 ++++++
 drivers/base/power/wakeup.c | 86 ++++++++++++++++++++++++++++++++++++-
 2 files changed, 99 insertions(+), 1 deletion(-)

diff --git a/drivers/base/power/power.h b/drivers/base/power/power.h
index 922ed457db19..ace190358eb3 100644
--- a/drivers/base/power/power.h
+++ b/drivers/base/power/power.h
@@ -168,3 +168,17 @@ static inline void device_pm_init(struct device *dev)
	device_pm_sleep_init(dev);
	pm_runtime_init(dev);
 }
+
+#ifdef CONFIG_DEBUG_INFO
+
+static inline char *pm_abort_suspend_source_name(void)
+{
+	char *source_name = kasprintf(GFP_ATOMIC, "%pS", __builtin_return_address(0));
+	return source_name;
+}
+
+#else
+
+	static inline char *pm_abort_suspend_source_name(void) { return NULL; }
+
+#endif /* CONFIG_DEBUG_INFO */
diff --git a/drivers/base/power/wakeup.c b/drivers/base/power/wakeup.c
index a917219feea6..aae9a5329bcb 100644
--- a/drivers/base/power/wakeup.c
+++ b/drivers/base/power/wakeup.c
@@ -73,6 +73,14 @@ static struct wakeup_source deleted_ws = {

 static DEFINE_IDA(wakeup_ida);

+static DEFINE_SPINLOCK(pm_abort_suspend_list_lock);
+
+struct pm_abort_suspend_source {
+	struct list_head list;
+	char *source_triggering_abort_suspend;
+};
+static LIST_HEAD(pm_abort_suspend_list);
+
 /**
  * wakeup_source_create - Create a struct wakeup_source object.
  * @name: Name of the new wakeup source.
@@ -575,6 +583,52 @@ static void wakeup_source_activate(struct wakeup_source *ws)
	trace_wakeup_source_activate(ws->name, cec);
 }

+/**
+ * pm_abort_suspend_list_clear - Clear pm_abort_suspend_list.
+ *
+ * The pm_abort_suspend_list will be cleared when system PM exits.
+ */
+static void pm_abort_suspend_list_clear(void)
+{
+	unsigned long flags;
+	struct pm_abort_suspend_source *info, *tmp;
+
+	spin_lock_irqsave(&pm_abort_suspend_list_lock, flags);
+	list_for_each_entry_safe(info, tmp, &pm_abort_suspend_list, list) {
+		list_del(&info->list);
+		kfree(info);
+	}
+	spin_unlock_irqrestore(&pm_abort_suspend_list_lock, flags);
+}
+
+/**
+ * pm_abort_suspend_source_add - Update pm_abort_suspend_list
+ * @source_name: Wakeup_source or function aborting suspend transitions.
+ *
+ * Add the source name responsible for updating the abort_suspend flag in the
+ * pm_abort_suspend_list.
+ */
+static void pm_abort_suspend_source_add(const char *source_name)
+{
+	unsigned long flags;
+	struct pm_abort_suspend_source *info;
+
+	info = kmalloc(sizeof(*info), GFP_ATOMIC);
+	if (!info)
+		return;
+
+	INIT_LIST_HEAD(&info->list);
+	info->source_triggering_abort_suspend = kstrdup(source_name, GFP_ATOMIC);
+	if (!info->source_triggering_abort_suspend) {
+		kfree(info);
+		return;
+	}
+
+	spin_lock_irqsave(&pm_abort_suspend_list_lock, flags);
+	list_add_tail(&info->list, &pm_abort_suspend_list);
+	spin_unlock_irqrestore(&pm_abort_suspend_list_lock, flags);
+}
+
 /**
  * wakeup_source_report_event - Report wakeup event using the given source.
  * @ws: Wakeup source to report the event for.
@@ -590,8 +644,11 @@ static void wakeup_source_report_event(struct wakeup_source *ws, bool hard)
	if (!ws->active)
		wakeup_source_activate(ws);

-	if (hard)
+	if (hard) {
+		if (pm_suspend_target_state != PM_SUSPEND_ON)
+			pm_abort_suspend_source_add(ws->name);
		pm_system_wakeup();
+	}
 }

 /**
@@ -893,12 +950,39 @@ bool pm_wakeup_pending(void)
		pm_print_active_wakeup_sources();
	}

+	if (atomic_read(&pm_abort_suspend) > 0) {
+		struct pm_abort_suspend_source *info;
+
+		spin_lock_irqsave(&pm_abort_suspend_list_lock, flags);
+		list_for_each_entry(info, &pm_abort_suspend_list, list) {
+			pm_pr_dbg("wakeup source or subsystem %s aborted suspend\n",
+					info->source_triggering_abort_suspend);
+		}
+		spin_unlock_irqrestore(&pm_abort_suspend_list_lock, flags);
+		pm_abort_suspend_list_clear();
+	}
+
	return ret || atomic_read(&pm_abort_suspend) > 0;
 }
 EXPORT_SYMBOL_GPL(pm_wakeup_pending);

 void pm_system_wakeup(void)
 {
+
+	if (pm_suspend_target_state != PM_SUSPEND_ON) {
+		char *source_name = pm_abort_suspend_source_name();
+
+		if (!source_name) {
+			pm_pr_dbg("Some wakeup source or subsystem aborted suspend\n");
+			goto exit;
+		}
+
+		if (strcmp(source_name, "pm_wakeup_ws_event"))
+			pm_abort_suspend_source_add(source_name);
+
+		kfree(source_name);
+	}
+exit:
	atomic_inc(&pm_abort_suspend);
	s2idle_wake();
 }
--
2.25.1