drivers: power: Add watchdog timer to catch drivers which lockup during suspend.
Rather than hard-lock the kernel, we now BUG() when a driver takes
> 3 seconds to suspend. If the underlying platform supports panic dumps,
then the data can be collected for debug.
Signed-off-by: San Mehat <san@google.com>
diff --git a/drivers/base/power/main.c b/drivers/base/power/main.c
index aa632020..c31045e 100644
--- a/drivers/base/power/main.c
+++ b/drivers/base/power/main.c
@@ -27,6 +27,7 @@
#include <linux/sched.h>
#include <linux/async.h>
#include <linux/suspend.h>
+#include <linux/timer.h>
#include "../base.h"
#include "power.h"
@@ -49,6 +50,9 @@
static DEFINE_MUTEX(dpm_list_mtx);
static pm_message_t pm_transition;
+static void dpm_drv_timeout(unsigned long data);
+static DEFINE_TIMER(dpm_drv_wd, dpm_drv_timeout, 0, 0);
+
static int async_error;
/**
@@ -573,6 +577,45 @@
}
/**
+ * dpm_drv_timeout - Driver suspend / resume watchdog handler
+ * @data: struct device which timed out
+ *
+ * Called when a driver has timed out suspending or resuming.
+ * There's not much we can do here to recover so
+ * BUG() out for a crash-dump
+ *
+ */
+static void dpm_drv_timeout(unsigned long data)
+{
+ struct device *dev = (struct device *) data;
+
+ printk(KERN_EMERG "**** DPM device timeout: %s (%s)\n", dev_name(dev),
+ (dev->driver ? dev->driver->name : "no driver"));
+ BUG();
+}
+
+/**
+ * dpm_drv_wdset - Sets up driver suspend/resume watchdog timer.
+ * @dev: struct device which we're guarding.
+ *
+ */
+static void dpm_drv_wdset(struct device *dev)
+{
+ dpm_drv_wd.data = (unsigned long) dev;
+ mod_timer(&dpm_drv_wd, jiffies + (HZ * 3));
+}
+
+/**
+ * dpm_drv_wdclr - clears driver suspend/resume watchdog timer.
+ * @dev: struct device which we're no longer guarding.
+ *
+ */
+static void dpm_drv_wdclr(struct device *dev)
+{
+ del_timer_sync(&dpm_drv_wd);
+}
+
+/**
* dpm_resume - Execute "resume" callbacks for non-sysdev devices.
* @state: PM transition of the system being carried out.
*
@@ -931,7 +974,9 @@
get_device(dev);
mutex_unlock(&dpm_list_mtx);
+ dpm_drv_wdset(dev);
error = device_suspend(dev);
+ dpm_drv_wdclr(dev);
mutex_lock(&dpm_list_mtx);
if (error) {