Messages in this thread | | | Date | Mon, 8 Apr 2013 16:14:50 +0200 | From | Hector Palacios <> | Subject | Re: [PATCH v2] watchdog: core: don't try to stop device if not running |
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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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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