[PATCH v3] watchdog: core: don't try to stop device if not running

From: Hector Palacios
Date: Mon Apr 08 2013 - 11:06:59 EST

A watchdog device may be stopped from userspace using WDIOC_SETOPTIONS
ioctl and flag WDIOS_DISABLECARD. If the device is closed after this
operation, watchdog_release() is called and status bits checked for
stopping it. Besides, if the device has not been unregistered a critical
message "watchdog did not stop!" is printed, although the ioctl may have
successfully stopped it already.

Without the patch a user application sample code like this will successfully
stop the watchdog, but the kernel will output the message
"watchdog did not stop!":

wd_fd = open("/dev/watchdog", O_RDWR);

ioctl(wd_fd, WDIOC_SETOPTIONS, &flags);


Signed-off-by: Hector Palacios <hector.palacios@xxxxxxxx>

Changes from v1:
- Make it less intrusive with 'if/else if' clauses.
- Change the logic of 'err' variable for better readability of code.
- Remove one-liner if brackets that broke coding sytle.
Changes from v2:
- Revert "Change the logic of 'err'..." from v1 because otherwise the
'else if' can't be reached if the watchdog is running.

drivers/watchdog/watchdog_dev.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/watchdog/watchdog_dev.c b/drivers/watchdog/watchdog_dev.c
index ef8edec..6117c48 100644
--- a/drivers/watchdog/watchdog_dev.c
+++ b/drivers/watchdog/watchdog_dev.c
@@ -470,8 +470,10 @@ static int watchdog_release(struct inode *inode, struct file *file)
* 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))
+ if (!test_bit(WDOG_ACTIVE, &wdd->status))
+ err = 0;
+ else 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 */

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