3 files changed, 99 insertions, 10 deletions

diff --git a/drivers/base/power/main.c b/drivers/base/power/main.c
index 9f098a82cf04..ee039afe9078 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);
diff --git a/kernel/power/Kconfig b/kernel/power/Kconfig
index d444c4e834f4..2fac9cc79b3d 100644
--- a/kernel/power/Kconfig
+++ b/kernel/power/Kconfig
@@ -178,6 +178,22 @@ config PM_SLEEP_DEBUG
         def_bool y
         depends on PM_DEBUG && PM_SLEEP
 
+config DPM_WATCHDOG
+        bool "Device suspend/resume watchdog"
+        depends on PM_DEBUG && PSTORE
+        ---help---
+          Sets up a watchdog timer to capture drivers that are
+          locked up attempting to suspend/resume a device.
+          A detected lockup causes system panic with message
+          captured in pstore device for inspection in subsequent
+          boot session.
+
+config DPM_WATCHDOG_TIMEOUT
+        int "Watchdog timeout in seconds"
+        range 1 120
+        default 12
+        depends on DPM_WATCHDOG
+
 config PM_TRACE
         bool
         help
diff --git a/kernel/power/user.c b/kernel/power/user.c
index 957f06164ad1..24850270c802 100644
--- a/kernel/power/user.c
+++ b/kernel/power/user.c
@@ -36,9 +36,9 @@ static struct snapshot_data {
         struct snapshot_handle handle;
         int swap;
         int mode;
-        char frozen;
-        char ready;
-        char platform_support;
+        bool frozen;
+        bool ready;
+        bool platform_support;
         bool free_bitmaps;
 } snapshot_state;
 
@@ -93,9 +93,9 @@ static int snapshot_open(struct inode *inode, struct file *filp)
         if (error)
                 atomic_inc(&snapshot_device_available);
 
-        data->frozen = 0;
-        data->ready = 0;
-        data->platform_support = 0;
+        data->frozen = false;
+        data->ready = false;
+        data->platform_support = false;
 
  Unlock:
         unlock_system_sleep();
@@ -229,7 +229,7 @@ static long snapshot_ioctl(struct file *filp, unsigned int cmd,
                 if (error)
                         thaw_processes();
                 else
-                        data->frozen = 1;
+                        data->frozen = true;
 
                 break;
 
@@ -240,7 +240,7 @@ static long snapshot_ioctl(struct file *filp, unsigned int cmd,
                 free_basic_memory_bitmaps();
                 data->free_bitmaps = false;
                 thaw_processes();
-                data->frozen = 0;
+                data->frozen = false;
                 break;
 
         case SNAPSHOT_CREATE_IMAGE:
@@ -270,7 +270,7 @@ static long snapshot_ioctl(struct file *filp, unsigned int cmd,
         case SNAPSHOT_FREE:
                 swsusp_free();
                 memset(&data->handle, 0, sizeof(struct snapshot_handle));
-                data->ready = 0;
+                data->ready = false;
                 /*
                  * It is necessary to thaw kernel threads here, because
                  * SNAPSHOT_CREATE_IMAGE may be invoked directly after
@@ -334,7 +334,7 @@ static long snapshot_ioctl(struct file *filp, unsigned int cmd,
                  * PM_HIBERNATION_PREPARE
                  */
                 error = suspend_devices_and_enter(PM_SUSPEND_MEM);
-                data->ready = 0;
+                data->ready = false;
                 break;
 
         case SNAPSHOT_PLATFORM_SUPPORT: