XPost: linux.debian.devel.release, linux.debian.maint.glibc
Hello,
On Wed, Jun 25, 2025 at 03:13:23PM +0200, Helmut Grohne wrote:
I talked to Aurelien on IRC. This mail gives some context and summarizes
our discussion.
I worked out and tested a patch somewhat and I also talked to Paul and
Ivo. Summarizing results here.
The other side is what I discussed with Aurelien and much of what
follows is due to him (thank you). systemd needs to be restarted when upgrading libc6, because it uses nss modules. Failing to do so results
in e.g. #993821. The way to restart systemd has changed over time. For instance, restarting user managers and other daemons such as resolved
has become a thing. Due to these changes, the responsibility of
restarting was eventually transferred to systemd via means of a dpkg
trigger (see #1074607) and the Breaks ensures that systemd can handle
the trigger. The Breaks declaration shall ensure that systemd ends up
being restarted, but what also does is require that systemd.postinst is
run before libc6.postinst. We observe that we do not expect to bump the Breaks version in forky as it is an artifact of transitioning to dpkg triggers, so in later dist-upgrades the cycle at hand is expected to disappear. If we are trying to relax it, we'd have to re-add code for restarting systemd to libc6.postinst:
if the installed systemd does not support triggers; then
# Expect a bookworm systemd:
# * If it were older, we'd be doing a skip upgrade.
# * If it is newer (e.g. backports), it supports triggers.
restart systemd the bookworm way
# https://sources.debian.org/src/systemd/252.36-1~deb12u1/debian/systemd.postinst/#L77
fi
I note that this is the code that Aurelien spent effort on to get
removed from libc6 and moved into glibc. He expressed that he does not
like this approach (for obvious reasons).
I have prepared patch for glibc that drops the Breaks and adds he init
script. Tests performed:
*
https://debusine.debian.net/debian/developers/work-request/103866/
* Attempted to reproduce the problem with Breaks dropped, but I could
not reproduce it then. apt would simply upgrade libc6 earlier and not
do stupid things.
* Upgraded just libc6 in a VM (not container) and observed that systemd
would properly be restarted when expected.
I hope that others agree with this level of testing striking a good
balance on effort and risk.
Talking to the release team, Ivo and Paul were not super happy with the maintainer script changes due to the risk involved in added code. They
pointed out that the lack of that addition would result in a risk of
people doing a partial upgrade (i.e. libc6, but not systemd) would not
get their systemd restarted. According to them, the scenario is quite
unlikely in a release upgrade and that people should not be doing
partial upgrades. If systemd is upgraded, it restarts itself. If libc
happens to be upgraded after systemd has done this restart, the trigger
added in trixie still will work. The one case the Breaks help is when
you upgrade libc6 but not systemd. Therefore, they suggested merely
dropping the Breaks without adding to the maintainer script.
I am fine either way. Dropping the breaks is what makes package
installation no longer fail.
Aurelien, are you happy with doing an upload with or without maintainer
script changes?
Release team, can you vaguely pre-approve the attached patch with or
without maintainer script changes?
Whilst the patch closes the bug, I think that Chris' original assignment
to apt bears some truth. What apt does here makes no sense to me. I
haven't had a chance talk to Julian though.
Helmut
diff -Nru glibc-2.41/debian/changelog glibc-2.41/debian/changelog
--- glibc-2.41/debian/changelog 2025-06-18 06:49:31.000000000 +0200
+++ glibc-2.41/debian/changelog 2025-07-06 17:45:51.000000000 +0200
@@ -1,3 +1,10 @@
+glibc (2.41-9.1) UNRELEASED; urgency=medium
+
+ * Non-maintainer upload.
+ * Partially restore init restarting. (Closes: #1108193)
+
+ -- Helmut Grohne <
[email protected]> Sun, 06 Jul 2025 17:45:51 +0200
+
glibc (2.41-9) unstable; urgency=medium
[ Aurelien Jarno ]
diff -Nru glibc-2.41/debian/control glibc-2.41/debian/control
--- glibc-2.41/debian/control 2025-06-18 06:49:31.000000000 +0200
+++ glibc-2.41/debian/control 2025-07-06 17:45:25.000000000 +0200
@@ -166,7 +166,7 @@
Suggests: glibc-doc, debconf | debconf-2.0, libc-l10n, locales [!hurd-any], libnss-nis, libnss-nisplus
Provides: libc6-sparcv9b [sparc sparc64], libc0.3-i686 [hurd-i386], libc6-i686 [i386]
Conflicts: libc6-i686 [i386], libc6.1-alphaev67 [alpha]
-Breaks: nscd (<< 2.41), locales (<< 2.41), locales-all (<< 2.41), gnumach-image-1.8-486 (<< 2:1.8+git20210923~),