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authorWim Van Sebroeck <wim@iguana.be>2011-07-22 18:59:17 +0000
committerWim Van Sebroeck <wim@iguana.be>2011-07-28 08:01:14 +0000
commit7e192b9c4234d29bdc20ac8d0a67edf7624b4206 (patch)
treed46f8208ce67391166e8fbdcc3fe92e6ee01ea3c /drivers/watchdog
parent017cf0805105496ab1880e236cb3e4bf156fb915 (diff)
downloadlinux-7e192b9c4234d29bdc20ac8d0a67edf7624b4206.tar.bz2
watchdog: WatchDog Timer Driver Core - Add nowayout feature
Add support for the nowayout feature to the WatchDog Timer Driver Core framework. This feature prevents the watchdog timer from being stopped. Signed-off-by: Alan Cox <alan@lxorguk.ukuu.org.uk> Signed-off-by: Wim Van Sebroeck <wim@iguana.be> Acked-by: Arnd Bergmann <arnd@arndb.de> Acked-by: Wolfram Sang <w.sang@pengutronix.de>
Diffstat (limited to 'drivers/watchdog')
-rw-r--r--drivers/watchdog/watchdog_dev.c18
1 files changed, 13 insertions, 5 deletions
diff --git a/drivers/watchdog/watchdog_dev.c b/drivers/watchdog/watchdog_dev.c
index db40c6c79ef8..ac20f92347b1 100644
--- a/drivers/watchdog/watchdog_dev.c
+++ b/drivers/watchdog/watchdog_dev.c
@@ -98,11 +98,18 @@ static int watchdog_start(struct watchdog_device *wddev)
* Stop the watchdog if it is still active and unmark it active.
* This function returns zero on success or a negative errno code for
* failure.
+ * If the 'nowayout' feature was set, the watchdog cannot be stopped.
*/
static int watchdog_stop(struct watchdog_device *wddev)
{
- int err;
+ int err = -EBUSY;
+
+ if (test_bit(WDOG_NO_WAY_OUT, &wdd->status)) {
+ pr_info("%s: nowayout prevents watchdog to be stopped!\n",
+ wdd->info->identity);
+ return err;
+ }
if (test_bit(WDOG_ACTIVE, &wdd->status)) {
err = wddev->ops->stop(wddev);
@@ -123,7 +130,7 @@ static int watchdog_stop(struct watchdog_device *wddev)
*
* A write to a watchdog device is defined as a keepalive ping.
* Writing the magic 'V' sequence allows the next close to turn
- * off the watchdog.
+ * off the watchdog (if 'nowayout' is not set).
*/
static ssize_t watchdog_write(struct file *file, const char __user *data,
@@ -271,8 +278,8 @@ out:
* @file: file handle to device
*
* This is the code for when /dev/watchdog gets closed. We will only
- * stop the watchdog when we have received the magic char, else the
- * watchdog will keep running.
+ * stop the watchdog when we have received the magic char (and nowayout
+ * was not set), else the watchdog will keep running.
*/
static int watchdog_release(struct inode *inode, struct file *file)
@@ -281,7 +288,8 @@ static int watchdog_release(struct inode *inode, struct file *file)
/*
* We only stop the watchdog if we received the magic character
- * or if WDIOF_MAGICCLOSE is not set
+ * or if WDIOF_MAGICCLOSE is not set. If nowayout was set then
+ * watchdog_stop will fail.
*/
if (test_and_clear_bit(WDOG_ALLOW_RELEASE, &wdd->status) ||
!(wdd->info->options & WDIOF_MAGICCLOSE))