watchdog: Introduce watchdog_stop_on_unregister helper

Many watchdog drivers explicitly stop the watchdog when unregistering it.
While it is unclear if this is actually needed (the whatdog should not be
running at that time if it can be stopped), introduce a helper to
explicitly stop the watchdog in the watchdog core when unregistering it.
This helps reducing driver code size while retaining functionality.

Signed-off-by: Guenter Roeck <linux@roeck-us.net>

diff --git a/Documentation/watchdog/watchdog-kernel-api.txt b/Documentation/watchdog/watchdog-kernel-api.txt
index ea277478982f5aef1e122f33f55140e8c5010fc4..9b93953f69cf866289fd8e49632860185bda1e6c 100644 (file)
--- a/Documentation/watchdog/watchdog-kernel-api.txt
+++ b/Documentation/watchdog/watchdog-kernel-api.txt
@@ -280,6 +280,12 @@ To disable the watchdog on reboot, the user must call the following helper:
 
 static inline void watchdog_stop_on_reboot(struct watchdog_device *wdd);
 
+To disable the watchdog when unregistering the watchdog, the user must call
+the following helper. Note that this will only stop the watchdog if the
+nowayout flag is not set.
+
+static inline void watchdog_stop_on_unregister(struct watchdog_device *wdd);
+
 To change the priority of the restart handler the following helper should be
 used:
 

diff --git a/drivers/watchdog/watchdog_dev.c b/drivers/watchdog/watchdog_dev.c
index 32930a073a12744b6d6cf1bcc0b154effea431ab..d5d2bbd8f428565357bb6e2f44be6adc9fa84701 100644 (file)
--- a/drivers/watchdog/watchdog_dev.c
+++ b/drivers/watchdog/watchdog_dev.c
@@ -987,6 +987,11 @@ static void watchdog_cdev_unregister(struct watchdog_device *wdd)
        wdd->wd_data = NULL;
        mutex_unlock(&wd_data->lock);
 
+       if (watchdog_active(wdd) &&
+           test_bit(WDOG_STOP_ON_UNREGISTER, &wdd->status)) {
+               watchdog_stop(wdd);
+       }
+
        cancel_delayed_work_sync(&wd_data->work);
 
        kref_put(&wd_data->kref, watchdog_core_data_release);

diff --git a/include/linux/watchdog.h b/include/linux/watchdog.h
index 35a4d8185b51cd83492743c043aea3ffa1eca9f9..a786e5e8973bff15e47c91b5ba8abbcf7e1bf4c8 100644 (file)
--- a/include/linux/watchdog.h
+++ b/include/linux/watchdog.h
@@ -117,6 +117,7 @@ struct watchdog_device {
 #define WDOG_NO_WAY_OUT                1       /* Is 'nowayout' feature set ? */
 #define WDOG_STOP_ON_REBOOT    2       /* Should be stopped on reboot */
 #define WDOG_HW_RUNNING                3       /* True if HW watchdog running */
+#define WDOG_STOP_ON_UNREGISTER        4       /* Should be stopped on unregister */
        struct list_head deferred;
 };
 
@@ -151,6 +152,12 @@ static inline void watchdog_stop_on_reboot(struct watchdog_device *wdd)
        set_bit(WDOG_STOP_ON_REBOOT, &wdd->status);
 }
 
+/* Use the following function to stop the watchdog when unregistering it */
+static inline void watchdog_stop_on_unregister(struct watchdog_device *wdd)
+{
+       set_bit(WDOG_STOP_ON_UNREGISTER, &wdd->status);
+}
+
 /* Use the following function to check if a timeout value is invalid */
 static inline bool watchdog_timeout_invalid(struct watchdog_device *wdd, unsigned int t)
 {