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watchdog: WatchDog Timer Driver Core - Add Magic Close feature

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Add support for the Magic Close feature to the
WatchDog Timer Driver Core framework.

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 18:58:54 +00:00
parent 014d694e5d
commit 017cf08051
3 changed files with 32 additions and 3 deletions
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27
drivers/watchdog/watchdog_dev.c
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@@ -122,6 +122,8 @@ static int watchdog_stop(struct watchdog_device *wddev)
* @ppos: pointer to the file offset
*
* 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.
*/
static ssize_t watchdog_write(struct file *file, const char __user *data,
@@ -133,9 +135,18 @@ static ssize_t watchdog_write(struct file *file, const char __user *data,
if (len == 0)
return 0;
/*
* Note: just in case someone wrote the magic character
* five months ago...
*/
clear_bit(WDOG_ALLOW_RELEASE, &wdd->status);
/* scan to see whether or not we got the magic character */
for (i = 0; i != len; i++) {
if (get_user(c, data + i))
return -EFAULT;
if (c == 'V')
set_bit(WDOG_ALLOW_RELEASE, &wdd->status);
}
/* someone wrote to us, so we send the watchdog a keepalive ping */
@@ -259,14 +270,24 @@ out:
* @inode: inode of device
* @file: file handle to device
*
* This is the code for when /dev/watchdog gets closed.
* 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.
*/
static int watchdog_release(struct inode *inode, struct file *file)
{
int err;
int err = -EBUSY;
err = watchdog_stop(wdd);
/*
* We only stop the watchdog if we received the magic character
* or if WDIOF_MAGICCLOSE is not set
*/
if (test_and_clear_bit(WDOG_ALLOW_RELEASE, &wdd->status) ||
!(wdd->info->options & WDIOF_MAGICCLOSE))
err = watchdog_stop(wdd);
/* If the watchdog was not stopped, send a keepalive ping */
if (err < 0) {
pr_crit("%s: watchdog did not stop!\n", wdd->info->identity);
watchdog_ping(wdd);