lttng-modules-dkms fails to build on focal with linux hwe 5.15

[Andrea Righi]

[Impact]

lttng-modules-dkms fails to build on focal using kernel 5.15 with the following error:

/home/ubuntu/lttng-modules-2.12.5/lib/ringbuffer/ring_buffer_frontend.c: In function ‘lib_ring_buffer_set_quiescent_channel’:
/home/ubuntu/lttng-modules-2.12.5/lib/ringbuffer/ring_buffer_frontend.c:759:3: error: implicit declaration of function ‘get_online_cpus’; did you mean ‘get_online_mems’? [-Werror=implicit-function-declaration]
  759 | get_online_cpus();
      | ^~~~~~~~~~~~~~~
      | get_online_mems
/home/ubuntu/lttng-modules-2.12.5/lib/ringbuffer/ring_buffer_frontend.c:766:3: error: implicit declaration of function ‘put_online_cpus’; did you mean ‘num_online_cpus’? [-Werror=implicit-function-declaration]
  766 | put_online_cpus();
      | ^~~~~~~~~~~~~~~
      | num_online_cpus
cc1: some warnings being treated as errors

[Test case]

 $ sudo apt install lttng-modules-dkms

[Fix]

Backport upstream fixes to support kernels >= 5.14.

[Regression potential]

We may notice regressions with lttng-modules on kernels < 5.14.

[Andrea Righi (arighi)]

debdiff in attach fixes build failures on focal with linux hwe 5.15.

[Dimitri John Ledkov (xnox)]

Sponsored as 2.12.5-1ubuntu2~20.04.2

[Brian Murray (brian-murray)]

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/2.12.5-1ubuntu2~20.04.2 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.

[Dimitri John Ledkov (xnox)]

1) launched focal lxd container
2) enabled proposed
3) installed the v5.15 based kernel
apt install linux-generic-hwe-20.04-edge
4) disabled proposed

5) observed that it fails to install

Setting up lttng-modules-dkms (2.12.5-1ubuntu2~20.04.1) ...
Loading new lttng-modules-2.12.5 DKMS files...
It is likely that 5.13.0-40-generic belongs to a chroot's host
Building for 5.15.0-25-generic
Building initial module for 5.15.0-25-generic
Error! Bad return status for module build on kernel: 5.15.0-25-generic (x86_64)
Consult /var/lib/dkms/lttng-modules/2.12.5/build/make.log for more information.
dpkg: error processing package lttng-modules-dkms (--configure):
 installed lttng-modules-dkms package post-installation script subprocess returned error ex
it status 10

6) enabled proposed once again

7) observed that from proposed installs & builds fine

Setting up lttng-modules-dkms (2.12.5-1ubuntu2~20.04.2) ...
Loading new lttng-modules-2.12.5 DKMS files...
It is likely that 5.13.0-40-generic belongs to a chroot's host
Building for 5.15.0-25-generic
Building initial module for 5.15.0-25-generic
Done.

lttng-lib-ring-buffer.ko:
Running module version sanity check.
 - Original module
   - No original module exists within this kernel
 - Installation
   - Installing to /lib/modules/5.15.0-25-generic/updates/dkms/

lttng-ring-buffer-client-discard.ko:
Running module version sanity check.
 - Original module
   - No original module exists within this kernel
 - Installation
   - Installing to /lib/modules/5.15.0-25-generic/updates/dkms/

lttng-ring-buffer-client-mmap-discard.ko:
Running module version sanity check.
 - Original module
   - No original module exists within this kernel
 - Installation
   - Installing to /lib/modules/5.15.0-25-generic/updates/dkms/

lttng-ring-buffer-client-mmap-overwrite.ko:
Running module version sanity check.
 - Original module
   - No original module exists within this kernel
 - Installation
   - Installing to /lib/modules/5.15.0-25-generic/updates/dkms/

lttng-ring-buffer-client-overwrite.ko:
Running module version sanity check.
 - Original module
   - No original module exists within this kernel
 - Installation
   - Installing to /lib/modules/5.15.0-25-generic/updates/dkms/

lttng-ring-buffer-metadata-client.ko:
Running module version sanity check.
 - Original module
   - No original module exists within this kernel
 - Installation
   - Installing to /lib/modules/5.15.0-25-generic/updates/dkms/

lttng-ring-buffer-metadata-mmap-client.ko:
Running module version sanity check.
 - Original module
   - No original module exists within this kernel
 - Installation
   - Installing to /lib/modules/5.15.0-25-generic/updates/dkms/

lttng-clock.ko:
Running module version sanity check.
 - Original module
   - No original module exists within this kernel
 - Installation
   - Installing to /lib/modules/5.15.0-25-generic/updates/dkms/

lttng-statedump.ko:
Running module version sanity check.
 - Original module
   - No original module exists within this kernel
 - Installation
   - Installing to /lib/modules/5.15.0-25-generic/updates/dkms/

lttng-tracer.ko:
Running module version sanity check.
 - Original module
   - No original module exis...

[Launchpad Janitor (janitor)]

This bug was fixed in the package lttng-modules - 2.12.5-1ubuntu2~20.04.2

---------------
lttng-modules (2.12.5-1ubuntu2~20.04.2) focal; urgency=medium

  * Cherry picks support for kernel >= v5.14 from
    upstream/stable-2.12. (LP: #1960165)

 -- Andrea Righi <email address hidden> Sun, 06 Feb 2022 17:07:00 +0000

[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.

[Ravishankar (rreddy78)]

Sorry, but is this fix released for Package: lttng-modules-dkms Version: 2.12.6-1~ubuntu20.04.1 ?
I am getting the same error when I try to install this on my system:

uname -a
Linux BANO-C-0012R 5.15.0-57-generic #63~20.04.1-Ubuntu SMP Wed Nov 30 13:40:16 UTC 2022 x86_64 x86_64 x86_64 GNU/Linux

Initial installation was a Ubuntu 20.4.1. Kernel was upgraded to 5.15 due for hardware support.