** Description changed: + [Impact] + + Linux 6.18 added a "struct file *filp" parameter to v4l2_fh_add() and + v4l2_fh_del() (include/media/v4l2-fh.h). + + v4l2loopback 0.12.7 still calls both with the old single-argument signature, so the DKMS build fails against the noble 7.0 HWE kernel: + v4l2loopback.c:2089: error: too few arguments to function 'v4l2_fh_add' + v4l2loopback.c:2117: error: too few arguments to function 'v4l2_fh_del' + + The impact is not limited to the virtual camera. + dkms autoinstall runs from /etc/kernel/header_postinst.d/dkms, so the build failure aborts the kernel header postinst with exit status 11 and leaves the kernel meta package unconfigured. + + Every subsequent apt operation, including security updates, then fails + until the user removes v4l2loopback-dkms by hand. + + linux-hwe-7.0 is published in both noble-updates and noble-security, so + affected systems receive the kernel automatically. + + 37 users are affected and 25 duplicates were filed within a week. + + Fixing only the call signature is not enough. + + 0.12.7 walks and reorders dev->outbufs_list in vidioc_dqbuf() without holding a lock, which panics with "list_del corruption" while streaming once the module builds again (LP: #2161239). + Both fixes are in this upload. + + [Test Plan] + + On a noble system with v4l2loopback-dkms installed: + sudo apt-get install -y linux-headers-7.0.0-28-generic + + - Without the fix + run-parts: /etc/kernel/header_postinst.d/dkms exited with return code 11 + dpkg: error processing package linux-headers-7.0.0-28-generic (--configure) + E: Sub-process /usr/bin/dpkg returned an error code (1) + + apt stays broken until v4l2loopback-dkms is removed. + + - With the fix + sudo apt-get install -y -t noble-proposed v4l2loopback-dkms + dkms status v4l2loopback + + The header package configures cleanly and dkms status reports v4l2loopback installed for 7.0.0-28-generic. + The GA kernel must be unaffected on the same system: + + sudo apt-get install -y linux-headers-6.8.0-136-generic + dkms status v4l2loopback + + The module must also build for 6.8.0-136-generic. + The locking fix, on a machine running 7.0: + + sudo modprobe v4l2loopback devices=1 + ffmpeg -re -f lavfi -i testsrc=size=640x480:rate=30 -t 60 -f v4l2 /dev/video0 & + ffplay -f v4l2 -i /dev/video0 + + Streaming must run to completion with the machine responsive. + Without the locking fix this panics and requires a hard power cycle. + + [Where problems could occur] + + If the compat macro guard or the new list_lock is wrong, the module + either stops building on one of the two kernels noble supports, leaving + apt in the broken state this SRU is fixing, or stalls every consumer of + the loopback device during output streaming. + + [Other Info] + + Fixed upstream in v4l2loopback 0.15.2 by + https://github.com/v4l2loopback/v4l2loopback/commit/3b09d3c53997f5f05e8d0db9222706585dbbe67a + Fix compilation with linux-6.18.0 + (with its follow-up ce8474158c6e, which applies the same change to v4l2_fh_del) + + [ORIGINAL DESCRIPTION] + v4l2loopback.c: In function ‘v4l2_loopback_open’: v4l2loopback.c:2089:9: error: too few arguments to function ‘v4l2_fh_add’ 2089 | v4l2_fh_add(&opener->fh); | ^~~~~~~~~~~ In file included from /usr/src/linux-headers-7.0.0-28-generic/include/media/v4l2-subdev.h:17, from /usr/src/linux-headers-7.0.0-28-generic/include/media/v4l2-device.h:13, from v4l2loopback.c:31: /usr/src/linux-headers-7.0.0-28-generic/include/media/v4l2-fh.h:97:6: note: declared here 97 | void v4l2_fh_add(struct v4l2_fh *fh, struct file *filp); | ^~~~~~~~~~~ v4l2loopback.c: In function ‘v4l2_loopback_close’: v4l2loopback.c:2117:9: error: too few arguments to function ‘v4l2_fh_del’ 2117 | v4l2_fh_del(&opener->fh); | ^~~~~~~~~~~ /usr/src/linux-headers-7.0.0-28-generic/include/media/v4l2-fh.h:125:6: note: declared here 125 | void v4l2_fh_del(struct v4l2_fh *fh, struct file *filp); | ^~~~~~~~~~~ ProblemType: Package DistroRelease: Ubuntu 24.04 Package: linux-headers-7.0.0-28-generic 7.0.0-28.28~24.04.1 ProcVersionSignature: Ubuntu 6.17.0-35.35~24.04.1-generic 6.17.13 Uname: Linux 6.17.0-35-generic x86_64 NonfreeKernelModules: nvidia_modeset nvidia ApportVersion: 2.28.2-0ubuntu0.1 Architecture: amd64 AudioDevicesInUse: USER PID ACCESS COMMAND /dev/snd/controlC0: tom-brown 2572 F.... wireplumber /dev/snd/controlC1: tom-brown 2572 F.... wireplumber /dev/snd/seq: tom-brown 2567 F.... pipewire CRDA: N/A CasperMD5CheckResult: pass Date: Thu Jul 16 22:52:40 2026 ErrorMessage: installed linux-headers-7.0.0-28-generic package post-installation script subprocess returned error exit status 11 InstallationDate: Installed on 2025-12-20 (209 days ago) InstallationMedia: Ubuntu 24.04.3 LTS "Noble Numbat" - Release amd64 (20250805.1) Lsusb: Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub Bus 001 Device 002: ID 046d:c52b Logitech, Inc. Unifying Receiver Bus 001 Device 003: ID 8087:0a2b Intel Corp. Bluetooth wireless interface Bus 001 Device 004: ID 0bda:57c3 Realtek Semiconductor Corp. Integrated_Webcam_HD Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub MachineType: Dell Inc. Precision 7510 ProcFB: 0 i915drmfb ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-6.17.0-35-generic root=UUID=0cd37cd1-1382-4191-9107-b090419b644e ro quiet splash vt.handoff=7 Python3Details: /usr/bin/python3.12, Python 3.12.3, python3-minimal, 3.12.3-0ubuntu2.1 PythonDetails: N/A RelatedPackageVersions: grub-pc N/A SourcePackage: linux-hwe-7.0 Title: package linux-headers-7.0.0-28-generic 7.0.0-28.28~24.04.1 failed to install/upgrade: installed linux-headers-7.0.0-28-generic package post-installation script subprocess returned error exit status 11 UpgradeStatus: No upgrade log present (probably fresh install) dmi.bios.date: 03/09/2023 dmi.bios.release: 1.31 dmi.bios.vendor: Dell Inc. dmi.bios.version: 1.31.3 dmi.board.name: 0MJ7KG dmi.board.vendor: Dell Inc. dmi.board.version: A00 dmi.chassis.type: 9 dmi.chassis.vendor: Dell Inc. dmi.modalias: dmi:bvnDellInc.:bvr1.31.3:bd03/09/2023:br1.31:svnDellInc.:pnPrecision7510:pvr:rvnDellInc.:rn0MJ7KG:rvrA00:cvnDellInc.:ct9:cvr:sku06D9: dmi.product.family: Precision dmi.product.name: Precision 7510 dmi.product.sku: 06D9 dmi.sys.vendor: Dell Inc.
-- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/2161037 Title: v4l2loopback fails to build on kernel 7.0 HWE To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/v4l2loopback/+bug/2161037/+subscriptions -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
