r8168-dkms 8.048.00-1: r8168 kernel module failed to build

[SRU Justification]

Impact: In kernel 5.6 there was a rename of a structure and change of arguments to a kernel interface function. The driver version in 20.04/Focal will fail to compile for the 5.8 HWE kernel once this is available.

Fix: Additional compatibility code which adjusted for the modified interfaces on kernel versions 5.6 and later was picked from a later version of the driver.

Testcase: dkms install -m r8168 -v 8.048.00 -k <kvers>

Regression Potential: As the code is unchanged for the release version of the kernel there is no potential for regression there. However for newer kernels there might be unknown issues but right now the driver does not compile in those cases. So being able to find those issues already is an improvement.

--- Original description ---

DKMS make.log for r8168-8.048.00 for kernel 5.6.0-1021-oem (x86_64)
Tue 18 Aug 2020 12:49:54 PM PDT
make: Entering directory '/usr/src/linux-headers-5.6.0-1021-oem'
  AR /var/lib/dkms/r8168/8.048.00/build/built-in.a
  CC [M] /var/lib/dkms/r8168/8.048.00/build/r8168_n.o
  CC [M] /var/lib/dkms/r8168/8.048.00/build/r8168_asf.o
  CC [M] /var/lib/dkms/r8168/8.048.00/build/rtl_eeprom.o
  CC [M] /var/lib/dkms/r8168/8.048.00/build/rtltool.o
/var/lib/dkms/r8168/8.048.00/build/r8168_n.c: In function ‘rtl8168_proc_init’:
/var/lib/dkms/r8168/8.048.00/build/r8168_n.c:1670:47: error: passing argument 4 of ‘proc_create_data’ from incompatible pointer type [-Werror=incompatible-pointer-types]
 1670 | &rtl8168_proc_fops, f->show)) {
      | ^~~~~~~~~~~~~~~~~~
      | |
      | const struct file_operations *
In file included from /var/lib/dkms/r8168/8.048.00/build/r8168_n.c:92:
./include/linux/proc_fs.h:59:31: note: expected ‘const struct proc_ops *’ but argument is of type ‘const struct file_operations *’
   59 | extern struct proc_dir_entry *proc_create_data(const char *, umode_t,
      | ^~~~~~~~~~~~~~~~
/var/lib/dkms/r8168/8.048.00/build/r8168_n.c: At top level:
/var/lib/dkms/r8168/8.048.00/build/r8168_n.c:25825:31: error: initialization of ‘void (*)(struct net_device *, unsigned int)’ from incompatible pointer type ‘void (*)(struct net_device *)’ [-Werror=incompatible-pointer-types]
25825 | .ndo_tx_timeout = rtl8168_tx_timeout,
      | ^~~~~~~~~~~~~~~~~~
/var/lib/dkms/r8168/8.048.00/build/r8168_n.c:25825:31: note: (near initialization for ‘rtl8168_netdev_ops.ndo_tx_timeout’)
cc1: some warnings being treated as errors
make[1]: *** [scripts/Makefile.build:275: /var/lib/dkms/r8168/8.048.00/build/r8168_n.o] Error 1
make: *** [Makefile:1707: /var/lib/dkms/r8168/8.048.00/build] Error 2
make: Leaving directory '/usr/src/linux-headers-5.6.0-1021-oem'

ProblemType: Package
DistroRelease: Ubuntu 20.04
Package: r8168-dkms 8.048.00-1
ProcVersionSignature: Ubuntu 5.6.0-1020.20-oem 5.6.19
Uname: Linux 5.6.0-1020-oem x86_64
ApportVersion: 2.20.11-0ubuntu27.6
Architecture: amd64
CasperMD5CheckResult: skip
DKMSKernelVersion: 5.6.0-1020-oem
Date: Wed Aug 12 12:37:38 2020
DuplicateSignature: dkms:r8168-dkms:8.048.00-1:/var/lib/dkms/r8168/8.048.00/build/r8168_n.c:1670:47: error: passing argument 4 of ‘proc_create_data’ from incompatible pointer type [-Werror=incompatible-pointer-types]
InstallationDate: Installed on 2020-08-11 (6 days ago)
InstallationMedia: Ubuntu 20.04.1 LTS "Focal Fossa" - Release amd64 (20200731)
PackageArchitecture: all
PackageVersion: 8.048.00-1
Python3Details: /usr/bin/python3.8, Python 3.8.2, python3-minimal, 3.8.2-0ubuntu2
PythonDetails: N/A
RelatedPackageVersions:
 dpkg 1.19.7ubuntu3
 apt 2.0.2ubuntu0.1
SourcePackage: r8168
Title: r8168-dkms 8.048.00-1: r8168 kernel module failed to build
UpgradeStatus: No upgrade log present (probably fresh install)