[Bug 1560545] Re: [FFe] hwup/down is racy, migrate to chzdev (previously: Some or all OSA devices may be unavailable after boot if too many are visible)

[Dimitri John Ledkov]

debian-installer 20101020ubuntu447 or better is required, also
sysconfig-hardware package 0.0.13ubuntu3 or better is required. This
means that tomorrows server daily iso image can be used e.g.  20160414/
or a network installation against a mirror which has new enough
sysconfig-hardware synced.

Newly installed systems and upgraded systems will now use chzdev
persistent udev rules to bring up all devices both in the initramfs and
the running system.

hwup/hwdown utilities are deprecated, exit 1, and direct users to use
lszdev and chzdev.

lszdev & chzdev utilitilies are now included in the d-i, initramfs and
installed system by default.

Installation using old archive & new installer are not supported.
Installations using old installer & new archive should work, and have been tested, however newly reported bug reports are best to be only filed against the new installer.

Please comment if you find bugs and/or are happy with this new
integration, and please indicate if there are races and/or missing
devices in big configurations.

There should be no errors in the journal about udev rules exiting with
error codes, and/or unknown udev keys or invalid udev rules.

** Changed in: ubuntu-z-systems
       Status: In Progress => Fix Committed

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Title:
  [FFe] hwup/down is racy, migrate to chzdev (previously: Some or all
  OSA devices may be unavailable after boot if too many are visible)

Status in Ubuntu on IBM z Systems:
  Fix Committed
Status in debian-installer package in Ubuntu:
  Fix Released
Status in s390-sysconfig-writer package in Ubuntu:
  Fix Released
Status in sysconfig package in Ubuntu:
  Fix Released

Bug description:
  1) modern udevd does not support WAIT_FOR_SYSFS stanza
  2) this introduces a sysfs race where devices are attempted to be configured, when not yet ready to be online

  since sysconfig, s390-tools has gained a modern toolset for activating
  s390x devices. The combination of tools is: lszdev & chzdev. One to ls
  devices on z, and another to change devices on z.

  the chzdev tool is flexible and can serialize/deserialize current
  state of devices, into a persistent state by generating appropriate
  race free udev rules.

  realistically sysconfig is currently sub-par solution which is not
  supportable for the duration of the LTS cycles. Whilst the chzdev
  tooling has IBM upstream support and is compatible with udev we
  currently ship and overall is more user-friendly and has better admin
  user experience, and script-ability.

  I'm requesting FFe to:
  - drop hwup/hwdown support
  - migrate hwup/hwdown configuration to chzdev udev rules
  - change installer to generate chzdev udev rules, instead of hwup/hwdown configuration

  Subject to testing:
  - full installer testing on all supported target platforms
  - upgrade testing of all supported target platforms

  Failing to land this for xenial, I shall seek to land this as an SRU.

  Regards,

  Dimitri.

  Original bug report below.

  -- Problem Description --
  Ubuntu 16.04 kernel 4.4.0-13 is installed on LPAR without cio_ignore in kernel command line, so a lot of devices are visible:

  root at s83lp41:~# ls -1U /sys/bus/ccw/drivers/qeth | wc -l
  154
  (50 OSA triplets + 4 non-devices)

  With so many devices the system may boot (initial or reboot) with only
  some or no interfaces brought up. A network is configured only on some
  of the triplets; the issue is well reproduced with two interfaces.

  lsqeth shows only active interfaces
  Inactive cannot be brought up with ifup:

  root at s83lp41:~# ifup encb080
  Cannot find device "encb080"
  Failed to bring up encb080.

  However, they become available after manually issuing hwup:

  root at s83lp41:~# hwup -A -D /devices/css0/0.0.1c67/0.0.b080 ccw 0.0.b080
  Configuring device 0.0.b080: ok. (portname OSAPORT) (portno 0) ok.

  After hwup interfaces are configured automatically and are listed in
  lsqeth.

  root at s83lp41:~# ifup encb080
  ifup: waiting for lock on /run/network/ifstate.encb080
  ifup: interface encb080 already configured

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