ddcci-driver-linux: build error with linux 5.15 on jammy

[Andrea Righi]

[Impact]

ddcci dkms is failing to build with the latest 5.15 kernel on jammy:

CC [M] /var/lib/dkms/ddcci/0.4.1/build/ddcci/ddcci.o
/var/lib/dkms/ddcci/0.4.1/build/ddcci/ddcci.c:1295:27: error: initialization of ‘void (*)(struct device *)’ from incompatible pointer type ‘int (*)(struct device *)’ [-Werror=incompatible-pointer-types]
 1295 | .remove = ddcci_device_remove
      | ^~~~~~~~~~~~~~~~~~~

[Test case]

sudo apt install ddcci-dkms

[Fix]

The signature of struct bus_type.remove changed to a void function, we just need to adjust the handler with kernels >= 5.15.

[Regression potential]

We may have ddcci-dkms regressions with old kernels if the patch is not doing the right thing, but the change is really minimal, so the risk of regressions is very low.

[Andrea Righi (arighi)]

Attached debdiff seems to fix the build error on 5.15 (tested in jammy with the latest kernel from -proposed).

[Dimitri John Ledkov (xnox)]

ddcci-driver-linux (0.4.1-2) unstable; urgency=medium

  * Adjust to build with kernel 5.15. Closes: #1000357.

 -- Stephen Kitt <email address hidden> Mon, 22 Nov 2021 18:24:42 +0100

[Andrea Righi (arighi)]

It looks like it's still broken:

  CC [M] /home/ubuntu/ddcci/ddcci-driver-linux-0.4.1/ddcci/ddcci.o
/home/ubuntu/ddcci/ddcci-driver-linux-0.4.1/ddcci/ddcci.c: In function ‘ddcci_device_remove’:
/home/ubuntu/ddcci/ddcci-driver-linux-0.4.1/ddcci/ddcci.c:1283:24: error: ‘return’ with a value, in function returning void [-Werror=return-type]
 1283 | return -EINVAL;
      | ^
/home/ubuntu/ddcci/ddcci-driver-linux-0.4.1/ddcci/ddcci.c:1273:13: note: declared here
 1273 | static void ddcci_device_remove(struct device *dev)
      | ^~~~~~~~~~~~~~~~~~~
cc1: some warnings being treated as errors
make[3]: *** [scripts/Makefile.build:285: /home/ubuntu/ddcci/ddcci-driver-linux-0.4.1/ddcci/ddcci.o] Error 1
make[2]: *** [Makefile:1880: /home/ubuntu/ddcci/ddcci-driver-linux-0.4.1/ddcci] Error 2

This is because ddcci_device_remove() is defined as void in 5.15, but there's a return -EINVAL in the body.

The fix for this is trivial, I'll post another debdiff.

[Andrea Righi (arighi)]

debdiff that fixes the new build error.

[Launchpad Janitor (janitor)]

This bug was fixed in the package ddcci-driver-linux - 0.4.1-3ubuntu1

---------------
ddcci-driver-linux (0.4.1-3ubuntu1) jammy; urgency=medium

  [ Andrea Righi ]
  * Fix build error on linux 5.15 (LP: #1951608)
    - debian/patches/0010-fix-build-error-with-linux-5.15.patch

  [ Dimitri John Ledkov ]
  * Drop the Debian's patch in favor of a better upstream patch
    cherrypicked by Andrea.

 -- Dimitri John Ledkov <email address hidden> Thu, 25 Nov 2021 15:33:56 +0000

[Andy Whitcroft (apw)]

Hello Andrea, or anyone else affected,

Accepted ddcci-driver-linux into focal-proposed. The package will build now and be available at https://launchpad.net/ubuntu/+source/ddcci-driver-linux/0.3.3-1ubuntu0.1 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.

[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

Loading new ddcci-0.3.3 DKMS files...
BACKLIGHT_CLASS_DEVICE disabled in this kernel, not building module.
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: Cannot create report: [Errno 17] File exists: '/var/crash/ddcci-dkms.0.crash'
Error! Bad return status for module build on kernel: 5.15.0-25-generic (x86_64)
Consult /var/lib/dkms/ddcci/0.3.3/build/make.log for more information.
dpkg: error processing package ddcci-dkms (--configure):
 installed ddcci-dkms package post-installation script subprocess returned error exit statu
s 10
Errors were encountered while processing:
 ddcci-dkms
E: Sub-process /usr/bin/dpkg returned an error code (1)

6) enabled proposed once again

7) observed that from proposed installs & builds fine

Setting up ddcci-dkms (0.3.3-1ubuntu0.1) ...
Loading new ddcci-0.3.3 DKMS files...
BACKLIGHT_CLASS_DEVICE disabled in this kernel, not building module.
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.

ddcci.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/

ddcci-backlight.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/

depmod...

DKMS: install completed.

[Launchpad Janitor (janitor)]

This bug was fixed in the package ddcci-driver-linux - 0.3.3-1ubuntu0.1

---------------
ddcci-driver-linux (0.3.3-1ubuntu0.1) focal; urgency=medium

  * Cherry-pick fix for failing to build from source on linux 5.15 from
    jammy. (LP: #1951608)

 -- Dimitri John Ledkov <email address hidden> Tue, 05 Apr 2022 16:19:23 +0100

[Brian Murray (brian-murray)]

The verification of the Stable Release Update for ddcci-driver-linux 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.