On Mon, Apr 08, 2013 at 09:48:57AM +0200, Hector Palacios wrote:
> On 04/05/2013 08:34 PM, Guenter Roeck wrote:
> >On Fri, Apr 05, 2013 at 06:09:44PM +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@xxxxxxxx>
> >
> >How about the following patch instead ?
> >
> >diff --git a/drivers/watchdog/watchdog_dev.c b/drivers/watchdog/watchdog_dev.c
> >index 08b48bb..9775e8d 100644
> >--- a/drivers/watchdog/watchdog_dev.c
> >+++ b/drivers/watchdog/watchdog_dev.c
> >@@ -469,7 +469,9 @@ 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) ||
> >+ 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);
> >
> >Much less invasive and the result is the same.
>
> I like the simplicity but it is kind of inverted logic to initially
> define err = -EBUSY only to turn it to zero later, so I'm rebuilding
> your approach like this:
>
> diff --git a/drivers/watchdog/watchdog_dev.c b/drivers/watchdog/watchdog_dev.c
> index ef8edec..a4163cd 100644
> --- a/drivers/watchdog/watchdog_dev.c
> +++ b/drivers/watchdog/watchdog_dev.c
> @@ -463,16 +463,19 @@ 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);
> + }
Ok, but the added { } are unnecessary and violate coding style rules.
Guenter
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