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watchdog: WatchDog Timer Driver Core - Add nowayout feature

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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>
This commit is contained in:
Wim Van Sebroeck
2011-07-22 18:59:17 +00:00
parent 017cf08051
commit 7e192b9c42
3 changed files with 22 additions and 10 deletions
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18
drivers/watchdog/watchdog_dev.c
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@@ -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))