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authorBenoit Goby <benoit@android.com>2013-10-17 10:48:46 -0700
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>2013-10-18 13:33:08 +0200
commit70fea60d888d472ac044910fd0dc46b304419705 (patch)
treeb5e884b2384ce0122481069aaa116678ea52bfa2 /drivers/base/power/main.c
parent61e6cfa80de5760bbe406f4e815b7739205754d2 (diff)
downloadop-kernel-dev-70fea60d888d472ac044910fd0dc46b304419705.zip
op-kernel-dev-70fea60d888d472ac044910fd0dc46b304419705.tar.gz
PM / Sleep: Detect device suspend/resume lockup and log event
Rather than hard-lock the kernel, dump the suspend/resume thread stack and panic() to capture a message in pstore when a driver takes too long to suspend/resume. Default suspend/resume watchdog timeout is set to 12 seconds to be longer than the usbhid 10 second timeout, but could be changed at compile time. Exclude from the watchdog the time spent waiting for children that are resumed asynchronously and time every device, whether or not they resumed synchronously. This patch is targeted for mobile devices where a suspend/resume lockup could cause a system reboot. Information about failing device can be retrieved in subsequent boot session by mounting pstore and inspecting the log. Laptops with EFI-enabled pstore could also benefit from this feature. The hardware watchdog timer is likely suspended during this time and couldn't be relied upon. The soft-lockup detector would eventually tell that tasks are not scheduled, but would provide little context as to why. The patch hence uses system timer and assumes it is still active while the devices are suspended/resumed. This feature can be enabled/disabled during kernel configuration. This change is based on earlier work by San Mehat. Signed-off-by: Benoit Goby <benoit@android.com> Signed-off-by: Zoran Markovic <zoran.markovic@linaro.org> Acked-by: Ulf Hansson <ulf.hansson@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Diffstat (limited to 'drivers/base/power/main.c')
-rw-r--r--drivers/base/power/main.c73
1 files changed, 73 insertions, 0 deletions
diff --git a/drivers/base/power/main.c b/drivers/base/power/main.c
index 9f098a8..ee039af 100644
--- a/drivers/base/power/main.c
+++ b/drivers/base/power/main.c
@@ -30,6 +30,8 @@
#include <linux/suspend.h>
#include <trace/events/power.h>
#include <linux/cpuidle.h>
+#include <linux/timer.h>
+
#include "../base.h"
#include "power.h"
@@ -390,6 +392,71 @@ static int dpm_run_callback(pm_callback_t cb, struct device *dev,
return error;
}
+#ifdef CONFIG_DPM_WATCHDOG
+struct dpm_watchdog {
+ struct device *dev;
+ struct task_struct *tsk;
+ struct timer_list timer;
+};
+
+#define DECLARE_DPM_WATCHDOG_ON_STACK(wd) \
+ struct dpm_watchdog wd
+
+/**
+ * dpm_watchdog_handler - Driver suspend / resume watchdog handler.
+ * @data: Watchdog object address.
+ *
+ * Called when a driver has timed out suspending or resuming.
+ * There's not much we can do here to recover so panic() to
+ * capture a crash-dump in pstore.
+ */
+static void dpm_watchdog_handler(unsigned long data)
+{
+ struct dpm_watchdog *wd = (void *)data;
+
+ dev_emerg(wd->dev, "**** DPM device timeout ****\n");
+ show_stack(wd->tsk, NULL);
+ panic("%s %s: unrecoverable failure\n",
+ dev_driver_string(wd->dev), dev_name(wd->dev));
+}
+
+/**
+ * dpm_watchdog_set - Enable pm watchdog for given device.
+ * @wd: Watchdog. Must be allocated on the stack.
+ * @dev: Device to handle.
+ */
+static void dpm_watchdog_set(struct dpm_watchdog *wd, struct device *dev)
+{
+ struct timer_list *timer = &wd->timer;
+
+ wd->dev = dev;
+ wd->tsk = current;
+
+ init_timer_on_stack(timer);
+ /* use same timeout value for both suspend and resume */
+ timer->expires = jiffies + HZ * CONFIG_DPM_WATCHDOG_TIMEOUT;
+ timer->function = dpm_watchdog_handler;
+ timer->data = (unsigned long)wd;
+ add_timer(timer);
+}
+
+/**
+ * dpm_watchdog_clear - Disable suspend/resume watchdog.
+ * @wd: Watchdog to disable.
+ */
+static void dpm_watchdog_clear(struct dpm_watchdog *wd)
+{
+ struct timer_list *timer = &wd->timer;
+
+ del_timer_sync(timer);
+ destroy_timer_on_stack(timer);
+}
+#else
+#define DECLARE_DPM_WATCHDOG_ON_STACK(wd)
+#define dpm_watchdog_set(x, y)
+#define dpm_watchdog_clear(x)
+#endif
+
/*------------------------- Resume routines -------------------------*/
/**
@@ -576,6 +643,7 @@ static int device_resume(struct device *dev, pm_message_t state, bool async)
pm_callback_t callback = NULL;
char *info = NULL;
int error = 0;
+ DECLARE_DPM_WATCHDOG_ON_STACK(wd);
TRACE_DEVICE(dev);
TRACE_RESUME(0);
@@ -584,6 +652,7 @@ static int device_resume(struct device *dev, pm_message_t state, bool async)
goto Complete;
dpm_wait(dev->parent, async);
+ dpm_watchdog_set(&wd, dev);
device_lock(dev);
/*
@@ -642,6 +711,7 @@ static int device_resume(struct device *dev, pm_message_t state, bool async)
Unlock:
device_unlock(dev);
+ dpm_watchdog_clear(&wd);
Complete:
complete_all(&dev->power.completion);
@@ -1060,6 +1130,7 @@ static int __device_suspend(struct device *dev, pm_message_t state, bool async)
pm_callback_t callback = NULL;
char *info = NULL;
int error = 0;
+ DECLARE_DPM_WATCHDOG_ON_STACK(wd);
dpm_wait_for_children(dev, async);
@@ -1083,6 +1154,7 @@ static int __device_suspend(struct device *dev, pm_message_t state, bool async)
if (dev->power.syscore)
goto Complete;
+ dpm_watchdog_set(&wd, dev);
device_lock(dev);
if (dev->pm_domain) {
@@ -1139,6 +1211,7 @@ static int __device_suspend(struct device *dev, pm_message_t state, bool async)
}
device_unlock(dev);
+ dpm_watchdog_clear(&wd);
Complete:
complete_all(&dev->power.completion);
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