udevadm settle waiting on an empty queue

udevadm settle waiting on an empty queue

[Marco d'Itri]

What could cause udevadm settle to wait even if the queue is empty?
Apparently this is fully reproducible by at least two users.

----- Forwarded message from Christopher Schramm <debian@shakaweb.org> -----

From: Christopher Schramm <debian@shakaweb.org>
To: Marco d'Itri <md@Linux.IT>
CC: 554364@bugs.debian.org

[...]

I just tried and found out the problem also occurs when calling udevadm
in the running system. So I can comfortably debug it if you tell me how
to start.

Output is "After the udevadm settle timeout, the events queue contains:"
with two empty lines above and three below.

----- End forwarded message -----

-- 
ciao,
Marco

Re: udevadm settle waiting on an empty queue

[Alan Jenkins]

On 11/5/09, Marco d'Itri <md@linux.it> wrote:
> What could cause udevadm settle to wait even if the queue is empty?
> Apparently this is fully reproducible by at least two users.
>
> ----- Forwarded message from Christopher Schramm <debian@shakaweb.org> -----
>
> From: Christopher Schramm <debian@shakaweb.org>
> To: Marco d'Itri <md@Linux.IT>
> CC: 554364@bugs.debian.org
>
> [...]
>
> I just tried and found out the problem also occurs when calling udevadm
> in the running system. So I can comfortably debug it if you tell me how
> to start.
>
> Output is "After the udevadm settle timeout, the events queue contains:"
> with two empty lines above and three below.
>
> ----- End forwarded message -----
>
> --
> ciao,
> Marco

Thanks.  I should be able to reproduce and debug it, given the
contents of /dev/.udev/queue.bin and /sys/kernel/uevent_seqnum.

I guess it's a bug in the binary queue I wrote.

This would happen if udevd was terminated, so that it didn't have a
change to remove /dev/.udev/queue.bin, and if an event occurred
subsequent to that.  But that's always been an issue and it doesn't
sound like it's whats happens here.

Regards
Alan

Re: udevadm settle waiting on an empty queue

[Alan Jenkins]

On 11/5/09, Christopher Schramm <debian@shakaweb.org> wrote:
> Alan Jenkins wrote:
>> Thanks.  I should be able to reproduce and debug it, given the
>> contents of /dev/.udev/queue.bin and /sys/kernel/uevent_seqnum.
>
> Please find attached.
>
> Best Regards
> Christopher Schramm
>

Re: udevadm settle waiting on an empty queue

[Alan Jenkins]

On 11/5/09, Christopher Schramm <debian@shakaweb.org> wrote:
> Alan Jenkins wrote:
>> Thanks.  I should be able to reproduce and debug it, given the
>> contents of /dev/.udev/queue.bin and /sys/kernel/uevent_seqnum.
>
> Please find attached.
>
> Best Regards
> Christopher Schramm
>

Ok, I failed to reproduce it.  But now I look at the archives I see
it's probably already been reported and fixed -

<http://www.spinics.net/lists/hotplug/msg02998.html>

Regards
Alan

Re: udevadm settle waiting on an empty queue

[Christopher Schramm]

Alan Jenkins wrote:
> Ok, I failed to reproduce it.  But now I look at the archives I see
> it's probably already been reported and fixed -
> 
> <http://www.spinics.net/lists/hotplug/msg02998.html>

Looks fine. Just downloaded current deb-src and applied the patch to
udev/udevadm-settle.c. Other than the one installed on my system, the
resulting udevadm does not block. :-)