[arch-projects] [initscripts][PATCH 0/3] Minor cleanup to rc and disabling udevadm settle

[Tom Gundersen]

On Sun, Apr 24, 2011 at 3:01 AM, Dave Reisner <d at falconindy.com> wrote:
> This is mostly for the first patch, which allows setting UDEV_TIMEOUT=0 to
> prevent 'udevadm settle' from being called. Looking back historically, this
> seems to cause a lot of grief with a lot of hardware. Googling turns up things
> such as...
>
> https://bugs.launchpad.net/ubuntu/+source/cryptsetup/+bug/387086
> https://bugzilla.redhat.com/show_bug.cgi?id=585527
> http://lkml.org/lkml/2011/4/12/538
> https://bbs.archlinux.org/viewtopic.php?id=117481

Why not just pass --timeout=0 to udev? Does that not work (from the
discussions I got the impression it  should)? It should check the
queue and return immediately, so basically the same as not calling
udevadm at all. It seems like a reasonable workaround for those who
need it.

> So, we're looking at both recent and less recent. Moreover, most people
> won't miss this if its disabled, as it's really just acting as a barrier
> for coldplug events to complete processing. As long as it's optional and
> documented, I think this is a reasonable thing to do.

I think it is wrong to say that most people will not miss this. We are
not able to deal with devices that appear after udevsettle, so if the
timeout is too short some drives might not get mounted.

I think we could support this as a hack for people who are hit by the
bugs you describe (if just passing --timeout=0 does not work), but we
should not give the impression that this is a proper fix (if ever the
timeout is reached it means something is broken...).

Cheers,

Tom