lttng-modules-dkms ADT test failure: build error with kernel >= 5.8

[Andrea Righi]

[Impact]

lttng-modules-dkms cannot be built anymore with kernels >= 5.8 (groovy).

The error reported is the following:

In file included from /var/lib/dkms/lttng-modules/2.12.2/build/probes/../probes/define_trace.h:87,
                 from /var/lib/dkms/lttng-modules/2.12.2/build/probes/../instrumentation/events/lttng-module/writeback.h:755,
                 from /var/lib/dkms/lttng-modules/2.12.2/build/probes/lttng-probe-writeback.c:38:
/var/lib/dkms/lttng-modules/2.12.2/build/probes/../probes/lttng-tracepoint-event-impl.h:131:6: error: conflicting types for ‘trace_writeback_queue_io’

The fix is already available in the upstream git repository.

[Test case]

Build the dkms package on a >= 5.8 kernel.

[Where problems could occur]

The upstream lttng-modules project is compatible and buildable on all >3.0 kernels. The new lttng-modules 2.12.2 code should continue to function fine on the 5.4 kernel.

I confirmed that the this latest package builds and loads without any errors or warnings on the 5.4 kernel.

Therefore, it is more accurate to say there is a small potential for regression on the 5.4 kernel - and that would likely indicate an upstream bug in lttng-modules itself.

[Launchpad Janitor (janitor)]

This bug was fixed in the package lttng-modules - 2.12.2-1ubuntu1

---------------
lttng-modules (2.12.2-1ubuntu1) groovy; urgency=medium

  * fix build bug with kernel 5.8. (LP: #1896077)

 -- Andrea Righi <email address hidden> Wed, 16 Sep 2020 14:26:51 +0000

[Łukasz Zemczak (sil2100)]

Since this is a standard dkms-package-fix, I'll accept it as is right now, but please update the bug description as per the usual SRU standards for DKMS packages. Thanks.

[Łukasz Zemczak (sil2100)]

...actually, looking at the changes, this is a direct backport of the latest version. I think I'd prefer a bit more work on the SRU bug in that case, mentioning the possible regression potential etc.

[Khaled El Mously (kmously)]

I responded to comment #4 at:

https://bugs.launchpad.net/ubuntu/+source/lttng-modules/+bug/1903952/comments/4

[Łukasz Zemczak (sil2100)]

Hello Andrea, or anyone else affected,

Accepted lttng-modules into focal-proposed. The package will build now and be available at https://launchpad.net/ubuntu/+source/lttng-modules/2.12.2-1ubuntu1~20.04.1 in a few hours, and then in the -proposed repository.

Please help us by testing this new package. See https://wiki.ubuntu.com/Testing/EnableProposed for documentation on how to enable and use -proposed. Your feedback will aid us getting this update out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug, mentioning the version of the package you tested, what testing has been performed on the package and change the tag from verification-needed-focal to verification-done-focal. If it does not fix the bug for you, please add a comment stating that, and change the tag to verification-failed-focal. In either case, without details of your testing we will not be able to proceed.

Further information regarding the verification process can be found at https://wiki.ubuntu.com/QATeam/PerformingSRUVerification . Thank you in advance for helping!

N.B. The updated package will be released to -updates after the bug(s) fixed by this package have been verified and the package has been in -proposed for a minimum of 7 days.

[Kleber Sacilotto de Souza (kleber-souza)]

Hi,

I confirm that lttng-modules 2.12.2-1ubuntu1~20.04.1 can be built and loaded on Focal with linux 5.4 and linux-hwe 5.8.

$ dkms status
lttng-modules, 2.12.2, 5.4.0-59-generic, x86_64: installed
lttng-modules, 2.12.2, 5.8.0-34-generic, x86_64: installed

I also smoke-tested the modules by running some traces with both kernels.

I have triggered ADT tests with linux-hwe-5.8 and they completed successfully:

amd64 - https://objectstorage.prodstack4-5.canonical.com/v1/AUTH_77e2ada1e7a84929a74ba3b87153c0ac/autopkgtest-focal/focal/amd64/l/lttng-modules/20201216_135414_638ee@/log.gz
arm64 - https://objectstorage.prodstack4-5.canonical.com/v1/AUTH_77e2ada1e7a84929a74ba3b87153c0ac/autopkgtest-focal/focal/arm64/l/lttng-modules/20201216_135852_48ab1@/log.gz
armhf - always failed in Focal.
ppc64el - https://objectstorage.prodstack4-5.canonical.com/v1/AUTH_77e2ada1e7a84929a74ba3b87153c0ac/autopkgtest-focal/focal/ppc64el/l/lttng-modules/20201216_134844_95721@/log.gz
s390x - https://objectstorage.prodstack4-5.canonical.com/v1/AUTH_77e2ada1e7a84929a74ba3b87153c0ac/autopkgtest-focal/focal/s390x/l/lttng-modules/20201216_134231_95721@/log.gz

Thanks,
Kleber

[Launchpad Janitor (janitor)]

This bug was fixed in the package lttng-modules - 2.12.2-1ubuntu1~20.04.1

---------------
lttng-modules (2.12.2-1ubuntu1~20.04.1) focal; urgency=medium

  [ Andrea Righi ]
  * Fix build bug with kernel 5.8. (LP: #1896077).

  * Use the Groovy version of lttng-modules with Focal.

 -- Khalid Elmously <email address hidden> Tue, 11 Nov 2020 00:26:51 -0500

[Brian Murray (brian-murray)]

The verification of the Stable Release Update for lttng-modules has completed successfully and the package is now being released to -updates. Subsequently, the Ubuntu Stable Release Updates Team is being unsubscribed and will not receive messages about this bug report. In the event that you encounter a regression using the package from -updates please report a new bug using ubuntu-bug and tag the bug report regression-update so we can easily find any regressions.