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@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 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 -- To unsubscribe from this list: send the line "unsubscribe linux-watchdog" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
