Messages in this thread | | | Date | Mon, 8 Apr 2013 10:43:52 +0200 | From | Hector Palacios <> | Subject | Re: [PATCH RFC] watchdog: core: don't try to stop device if not running |
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On 04/08/2013 10:16 AM, Guenter Roeck wrote: > 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@digi.com> >>> >>> 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.
Oops. Remainders of a debug message. Thanks for pointing out.
-- 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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