Re: [PATCH] Differentiate scenarios when watchdog is closed

[chaithco]

On Thu, Aug 27 2026 at 09:01:47 AM -07:00:00, Guenter Roeck 
<linux@xxxxxxxxxxxx> wrote:
> Presently
> [...]
> Also, the subject should start with the subsystem name ("watchdog:")
> [...]
> deliberately

Thank you for catching these! Please accept my apologies. I can fix 
those up in the next submission.

> [...] Also, while technically userspace may close the
> watchdog deliberately while it is running, that is not what happens
> on a regular basis.

This is actually what initiated a bug report at 
https://bugzilla.redhat.com/show_bug.cgi?id=1991285 it turns out 
systemd explicitly does this to help ensure a system shutting down 
actually eventually goes down even if the shutdown process hits some 
snags. It does this on every shutdown. Given the prevalence of systemd, 
this is a regular occurrence. The end result is that, when using iTCO, 
it shows an error on every shutdown when systemd is in use as init.

> If you want to make a change, I would suggest to add an error message
> into watchdog_stop() to report an error if the stop callback returns
> an error. That would distinguish 2/3 without making functional 
> changes.

Thank you! So something like this?

       if (wdd->ops->stop) {
               clear_bit(WDOG_HW_RUNNING, &wdd->status);
               err = wdd->ops->stop(wdd);
+               if (err < 0)
+                       pr_info("watchdog%d: closed while still 
enabled!\n");
               trace_watchdog_stop(wdd, err);
       } else {
               set_bit(WDOG_HW_RUNNING, &wdd->status);


While responding to this, an additional thought occurred to me; given 
the primary reason a user would see this is because systemd is shutting 
down a system, it may be more worth while to have systemd log something 
about closing the watchdog without disarming it to at least explain a 
pr_crit kernel log line. Otherwise, it just looks like "something bad 
happened" with watchdog. I am additionally unsure of what would be best 
to go in watchdog_stop that helps differentiate intentional closing of 
the watchdog without disabling vs malicious/accidental closing. The 
intent would lie within the entity closing the watchdog; "closed while 
still enabled!" still seems like "something bad happened" with info on 
if it was intentional or not.

Thank you!
- Charles