On Wed, 27 Mar 2013 21:44:21 +0100 Martin Wilck <mwilck@xxxxxxxx> wrote:
> Hi Neil,
>
> with my latest patch set, the DDF test case (10-ddf-create) succeeds
> reliably for me, with one caveat: It works only if I disable the rule
> that runs "mdadm -I" on a newly discovered container. On my system
> (Centos 6.3) it is in /lib/udev/65-md-incremental.rules, and the rule is
>
> SUBSYSTEM="block", ACTION="add|change", KERNEL="md*", \
> ENV{MD_LEVEL}=="container", RUN+="/sbin/mdadm -I $env{DEVNAME}"
>
> The reason is that the DDF test case runs mdadm -Asc after writing the
> conf file defining the container and 3 arrays.
>
> mdadm -Asc will first create the container. When it starts tries to
> create the member arrays, these have already been started by the udev
> rule above, causing the assembly to fail with the error message "member
> /dev/md127/1 in /dev/md127 is already assembled".
>
> I have done my testing with the above udev rule commented out, and all
> goes fine. But I am not sure if "mdadm -Asc /var/tmp/mdadm.conf" failing
> indicates a problem with the DDF code, or if it's really just a problem
> with the test case. Personally, I'd rather have a test case that
> succeeds by default on a system with standard configuration (which means
> the above udev rule should be active).
>
> What do you think?
> Martin
Hi Martin,
I think this is a real issue that has occasionally annoyed me a bit but
never enough to make me seriously address it - so thanks for raising it.
I generally would like the tests to run without any interference from udev,
though I certainly see the value of testing in a "standard config" context
too.
Fortunately it appears to be easy to address.
udevadm control --stop-exec-queue
will pause udev, and
udevadm control --start-exec-queue
will cause udev to resume.
So I suggest that we change the 'test' script to run:
udevadm settle; udevadm control --stop-exec-queue
before running each test script, and
udevadm control --start-exec-queue
after the script.
Then if a script wants to run in "standard" context, it could simply put
udevadm control --start-exec-queue
at the top. The default would be to disable udev which is what most scripts
expect.
Can you try that?
Thanks,
NeilBrown
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