Failed to build against linux-6.16

[You-Sheng Yang]

[ Impact ]

v4l2loopback fails to build on kernels > 6.16

from_timer macro renamed in v6.16-rc1 commit 41cb08555c416 ("treewide, timers: Rename from_timer() to timer_container_of()"):

CC [M] v4l2loopback.o
v4l2loopback.c: In function 'v4l2_loopback_add':
v4l2loopback.c:2910:9: error: implicit declaration of function 'setup_timer' [-Wimplicit-function-declaration]
 2910 | setup_timer(&dev->sustain_timer, sustain_timer_clb, nr);
      | ^~~~~~~~~~~
make[4]: *** [/usr/src/linux-headers-6.16.0-1-generic/scripts/Makefile.build:287: v4l2loopback.o] Error 1

[ Fix ]

Patch the dkms code to enable support for linux 6.16+

[ Test Plan ]

Install the latest linux-6.17 kernel on Noble:

$ sudo add-apt-repository ppa:canonical-kernel-team/ppa3
$ sudo apt install linux-generic-hwe-24.04-edge

Install v4l2loopback:

$ sudo apt install v4l2loopback-dkms

Module built and installed successfully

Load the module:

$ sudo modprobe v4l2loopback

Module loaded successfully

The same procedure must be repeated on linux-6.8 and linux-6.14 to test for possible regressions.

[ Regression Potential ]

We may experience regressions in systems that are using the v4l2loopback drivers, especially with kernels >= 6.8 kernel.

[You-Sheng Yang (vicamo)]

In v4l2loopback.c:
```
48 #if defined(timer_setup) && defined(from_timer)
49 #define HAVE_TIMER_SETUP
50 #endif
```

`timer_setup()` was first introduced in v4.14-rc3 commit 686fef928bba as a wrapper to `__setup_timer()`. Same for `from_timer()` macro. There is no reason to test both.

[You-Sheng Yang (vicamo)]

Have been resolved by upstream commit https://github.com/v4l2loopback/v4l2loopback/commit/196ae48c0f08dfcdcad0aded4917cf8a303bf237.

[You-Sheng Yang (vicamo)]

Attach debdiff for Questing. Also uploaded to https://launchpad.net/~vicamo/+archive/ubuntu/sru for easier review and verification.

Need sponsoring.

[Launchpad Janitor (janitor)]

This bug was fixed in the package v4l2loopback - 0.15.0-0ubuntu2

---------------
v4l2loopback (0.15.0-0ubuntu2) questing; urgency=medium

  * Failed to build against linux-6.16 (LP: #2114259)
    - 0002-Drop-from_timer-macro-usage.patch

 -- You-Sheng Yang <email address hidden> Mon, 16 Jun 2025 12:12:19 +0800

[You-Sheng Yang (vicamo)]

Nominate for Noble for linux-oem-6.17/noble. Plucky doesn't have linux kernel of v6.16+, so set INVALID.

[Andreas Hasenack (ahasenack)]

I don't see a diff or git branch linked to this bug for noble, and the questing one was sponsored already. Unsubscribing sponsors. When there is something new to sponsor, please resubscribe.

[You-Sheng Yang (vicamo)]

Attach debdiff for Noble. Also uploaded to https://launchpad.net/~vicamo/+archive/ubuntu/sru-2114259 for review/verification.

[Massimiliano Pellizzer (mpellizzer)]

Tested on Noble:
$ dkms status
v4l2loopback/0.12.7, 6.14.0-37-generic, x86_64: installed
v4l2loopback/0.12.7, 6.17.0-7-generic, x86_64: installed
v4l2loopback/0.12.7, 6.8.0-88-generic, x86_64: installed

Uploaded, thanks

[Timo Aaltonen (tjaalton)]

Hello You-Sheng, or anyone else affected,

Accepted v4l2loopback into noble-proposed. The package will build now and be available at https://launchpad.net/ubuntu/+source/v4l2loopback/0.12.7-2ubuntu5.1 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-noble to verification-done-noble. If it does not fix the bug for you, please add a comment stating that, and change the tag to verification-failed-noble. 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.

[You-Sheng Yang (vicamo)]

Verified build and function with also linux-oem-6.17 on Lenovo ThinkPad X1 Carbon Gen 12.