Bug#908796: udev (with sysvinit) fails to find devices at boot

[Trek]

On Sun, 7 Oct 2018 01:57:31 +0200
Michael Biebl <biebl at debian.org> wrote:

> > - We tweak the LSB headers to make sure the udev init script is
> > called before sendsigs on shutdown. This is important!
> 
> I have to add, that this change has the potential to significantly
> change the shutdown order or cause a conflicting ordering, in case
> there are other init scripts which declare an explicit shutdown
> dependency.

yes, this would create a circular dependency

before the 791944 patch, the shutdown sequence was:
K03sendsigs	(before umountnfs)
K05umountnfs	(before umountfs)
K07umountfs	(before umountroot)
K08cryptdisks	(after umountfs, before umountroot udev)
K10umountroot

if udev is stopped before sendsigs:
- cryptdisks should be stopped before udev
- umountfs should be stopped before cryptdisks
- umountnfs should be stopped before umountfs
- but sendsigs cannot be stopped after umountnfs

it can be easily resolved removing the udev entry in the Should-Stop
header of cryptdisks (and cryptdisks-early)


> Looking at https://codesearch.debian.net/ and searching for packages
> which declare a Should-Stop or Required-Stop on udev and checking if
> any late shutdown services are involved.

wow! I didn't know this site

with this simple search "Stop(|-After):.*udev", it returned these
packages that could be affected: multipath-tools, pcsc-lite,
network-manager, mouseemu, pulseaudio, cryptsetup, nut

it seems to me none of these packages would break (except cryptsetup)

this change should be mentioned in the NEWS.Debian file, as it could
break any script that depends on udev on shutdown and that is not
distributed by debian (open/closed source packages and system
administrator scripts)

the patches attached are tested on a system with swaps and filesystems
encrypted in plain mode (no luks, no cryptroot)

ciao!
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