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SubjectRe: [PATCH v2] watchdog: core: don't try to stop device if not running
On 04/08/2013 03:41 PM, Guenter Roeck wrote:
> On Mon, Apr 08, 2013 at 11:10:58AM +0200, Hector Palacios wrote:
>> 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);
>>
>> flags = WDIOS_DISABLECARD;
>> ioctl(wd_fd, WDIOC_SETOPTIONS, &flags);
>>
>> close(wd_fd);
>>
>> Signed-off-by: Hector Palacios <hector.palacios@digi.com>
>> ---
>>
>> 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
>>
>> drivers/watchdog/watchdog_dev.c | 8 +++++---
>> 1 file changed, 5 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/watchdog/watchdog_dev.c b/drivers/watchdog/watchdog_dev.c
>> index ef8edec..8e0f1b8 100644
>> --- a/drivers/watchdog/watchdog_dev.c
>> +++ b/drivers/watchdog/watchdog_dev.c
>> @@ -463,15 +463,17 @@ out:
>> static int watchdog_release(struct inode *inode, struct file *file)
>> {
>> struct watchdog_device *wdd = file->private_data;
>> - int err = -EBUSY;
>> + int err = 0;
>>
>> /*
>> * We only stop the watchdog if we received the magic character
>> * 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 = -EBUSY;
>> + else if (test_and_clear_bit(WDOG_ALLOW_RELEASE, &wdd->status) ||
>> + !(wdd->info->options & WDIOF_MAGICCLOSE))
>> err = watchdog_stop(wdd);
>>
> Looking at it again, it is now broken and fails with EBUSY if WDOG_ACTIVE is
> set, and it tries to stop the watchdog if it is already stopped.

You are right, good catch! So your patch version wins.
Thank you
--
Héctor Palacios
--
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