[PATCH v2 4/4] PM / core: Print warn if device gets enabled as wakeup source during sleep

From: Ulf Hansson <ulf.hansson@linaro.org>
To: "Rafael J . Wysocki" <rjw@rjwysocki.net>, linux-pm@vger.kernel.org
Cc: Kevin Hilman <khilman@kernel.org>,
	Viresh Kumar <viresh.kumar@linaro.org>,
	Geert Uytterhoeven <geert+renesas@glider.be>,
	Simon Horman <horms@verge.net.au>,
	Niklas Soderlund <niklas.soderlund+renesas@ragnatech.se>,
	Vincent Guittot <vincent.guittot@linaro.org>,
	linux-renesas-soc@vger.kernel.org,
	Ulf Hansson <ulf.hansson@linaro.org>
Subject: [PATCH v2 4/4] PM / core: Print warn if device gets enabled as wakeup source during sleep
Date: Fri, 29 Dec 2017 12:37:03 +0100	[thread overview]
Message-ID: <1514547423-18965-5-git-send-email-ulf.hansson@linaro.org> (raw)
In-Reply-To: <1514547423-18965-1-git-send-email-ulf.hansson@linaro.org>

In general, wakeup settings are not supposed to be changed during any of
the system wide PM phases. The reason is simply that it would break
guarantees provided by the PM core, to properly act on active wakeup
sources.

However, there are exceptions to when, in particular, disabling a device as
wakeup source makes sense. For example, in cases when a driver realizes
that its device is dead during system suspend. For these scenarios, we
don't need to care about acting on the wakeup source correctly, because a
dead device shouldn't deliver wakeup signals.

To this reasoning and to help users to properly manage wakeup settings,
let's print a warning in cases someone calls device_wakeup_enable() during
system sleep.

Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
---
 drivers/base/power/main.c   | 4 ++++
 drivers/base/power/wakeup.c | 4 ++++
 include/linux/pm.h          | 1 +
 3 files changed, 9 insertions(+)

diff --git a/drivers/base/power/main.c b/drivers/base/power/main.c
index 1327726..6b0d312 100644
--- a/drivers/base/power/main.c
+++ b/drivers/base/power/main.c
@@ -1030,6 +1030,8 @@ static void device_complete(struct device *dev, pm_message_t state)
 		callback(dev);
 	}
 
+	dev->power.may_set_wakeup = dev->power.can_wakeup;
+
 	device_unlock(dev);
 
 	pm_runtime_put(dev);
@@ -1747,6 +1749,7 @@ static int device_prepare(struct device *dev, pm_message_t state)
 
 	device_lock(dev);
 
+	dev->power.may_set_wakeup = false;
 	dev->power.wakeup_path = false;
 
 	if (dev->power.no_pm_callbacks) {
@@ -1775,6 +1778,7 @@ static int device_prepare(struct device *dev, pm_message_t state)
 	if (ret < 0) {
 		suspend_report_result(callback, ret);
 		pm_runtime_put(dev);
+		dev->power.may_set_wakeup = dev->power.can_wakeup;
 		return ret;
 	}
 	/*
diff --git a/drivers/base/power/wakeup.c b/drivers/base/power/wakeup.c
index cb72965..5445bea 100644
--- a/drivers/base/power/wakeup.c
+++ b/drivers/base/power/wakeup.c
@@ -268,6 +268,9 @@ int device_wakeup_enable(struct device *dev)
 	if (!dev || !dev->power.can_wakeup)
 		return -EINVAL;
 
+	if (!dev->power.may_set_wakeup)
+		dev_warn(dev, "don't enable as wakup source during sleep!\n");
+
 	ws = wakeup_source_register(dev_name(dev));
 	if (!ws)
 		return -ENOMEM;
@@ -413,6 +416,7 @@ void device_set_wakeup_capable(struct device *dev, bool capable)
 		return;
 
 	dev->power.can_wakeup = capable;
+	dev->power.may_set_wakeup = capable;
 	if (device_is_registered(dev) && !list_empty(&dev->power.entry)) {
 		if (capable) {
 			int ret = wakeup_sysfs_add(dev);
diff --git a/include/linux/pm.h b/include/linux/pm.h
index ebc6ef8..106fb15 100644
--- a/include/linux/pm.h
+++ b/include/linux/pm.h
@@ -606,6 +606,7 @@ struct dev_pm_info {
 	struct list_head	entry;
 	struct completion	completion;
 	struct wakeup_source	*wakeup;
+	bool			may_set_wakeup:1;
 	bool			wakeup_path:1;
 	bool			syscore:1;
 	bool			no_pm_callbacks:1;	/* Owned by the PM core */
-- 
2.7.4
