Re: [PATCH] common/rc: add default _udev_wait timeout

[David Disseldorp <ddiss@suse.de>]

On Thu, 19 Mar 2026 08:38:43 -0700, Darrick J. Wong wrote:

> On Thu, Mar 19, 2026 at 11:51:54AM +1100, David Disseldorp wrote:
> > If udevd isn't running then "udevadm wait" loops endlessly. With a
> > --timeout parameter provided, udevadm (udev-254.27) prints to stderr:
> >   Timed out for waiting devices being initialized.  
> 
> If you don't have udevd running, then perhaps we should detect that and
> directly call "sleep 10"?  Because otherwise...

I normally have udevd running, but sometimes mess it up. My latest screw
up came from ommitting a "/run" dir in the initramfs test env, which
causes systemd-udevd to die on "/run/udev" creation. The error message
is hard to spot amoungst the other boot messages...

> > The error message causes test failure via golden output mismatch and
> > is easier to debug than an infinite loop.
> > 
> > The timeout parameter is also compatible with existing
> > args="--removed <dev>" callers.
> > 
> > Signed-off-by: David Disseldorp <ddiss@suse.de>
> > ---
> >  common/rc | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/common/rc b/common/rc
> > index fd4ca964..aade0e5b 100644
> > --- a/common/rc
> > +++ b/common/rc
> > @@ -5544,7 +5544,7 @@ _udev_wait()
> >  	if [ -z "$UDEV_WAIT_PROG" ]; then
> >  		$UDEV_SETTLE_PROG >/dev/null 2>&1
> >  	else
> > -		$UDEV_WAIT_PROG $args
> > +		$UDEV_WAIT_PROG --timeout 10 $args  
> 
> ...a system running udevd that's taking forever to process rules can hit
> this 10 second timeout, at which point the test moves on and might just
> fail due to unconfigured /dev nodes.

The 10 seconds is arbitrary. If there's a concern that the timeout will
prematurely fire on a regular systems then I'll gladly raise it up to a
minute or so. I just want to get an explicit failure instead of a
never-ending test.

> /methinks this could be done like so:
> 
> 	if [ ! -S /run/udev/control ]; then
...

That's a good idea as a udevd sanity check. I'll add it to my test env. 

Thanks, David