diff options
Diffstat (limited to 'drivers/watchdog/watchdog_dev.c')
| -rw-r--r-- | drivers/watchdog/watchdog_dev.c | 27 |
1 files changed, 24 insertions, 3 deletions
diff --git a/drivers/watchdog/watchdog_dev.c b/drivers/watchdog/watchdog_dev.c index 2c0289deaadd..db40c6c79ef8 100644 --- a/drivers/watchdog/watchdog_dev.c +++ b/drivers/watchdog/watchdog_dev.c @@ -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; + + /* + * 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); - 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); |