[PATCH net v6 0/2] Enhance network interface feature testing

[Abhinav Jain <jain.abhinav177@gmail.com>]

This small series includes fixes for creation of veth pairs for
networkless kernels & adds tests for turning the different network
interface features on and off in selftests/net/netdevice.sh script.

Changes in v6:
Use XFAIL for ethtool operations that are unsupported instead of SKIP.

Changes in v5:
https://lore.kernel.org/all/20240808122452.25683-1-jain.abhinav177@gmail.com/

Rectify the syntax for ip add link.
Fix the veth_created condition check.

Changes in v4:
https://lore.kernel.org/all/20240807175717.7775-1-jain.abhinav177@gmail.com/

Move veth creation/removal to the main shell script.
Tested using vng on a networkless kernel and the script works, sample
output below the changes.

Changes in v3:
https://lore.kernel.org/all/20240614113240.41550-1-jain.abhinav177@gmail.com/

Add a check for netdev, create veth pair for testing.
Restore feature to its initial state.

Changes in v2:
https://lore.kernel.org/all/20240609132124.51683-1-jain.abhinav177@gmail.com/

Remove tail usage; use read to parse the features from temp file.

v1:
https://lore.kernel.org/all/20240606212714.27472-1-jain.abhinav177@gmail.com/

```
# selftests: net: netdevice.sh
# No valid network device found, creating veth pair
# PASS: veth0: set interface up
# PASS: veth0: set MAC address
# SKIP: veth0: set IP address
# PASS: veth0: ethtool list features
# PASS: veth0: Turned off feature: rx-checksumming
# PASS: veth0: Turned on feature: rx-checksumming
# PASS: veth0: Restore feature rx-checksumming to initial state on
# Actual changes:


# PASS: veth0: Restore feature rx-gro-list to initial state off
# PASS: veth0: Turned off feature: rx-udp-gro-forwarding
# PASS: veth0: Turned on feature: rx-udp-gro-forwarding
# PASS: veth0: Restore feature rx-udp-gro-forwarding to initial state off
# Cannot get register dump: Operation not supported
# XFAIL: veth0: ethtool dump not supported
# PASS: veth0: ethtool stats
# PASS: veth0: stop interface
```

Abhinav Jain (2):
  selftests: net: Create veth pair for testing in networkless kernel
  selftests: net: Add on/off checks for non-fixed features of interface

 tools/testing/selftests/net/netdevice.sh | 55 +++++++++++++++++++++++-
 1 file changed, 53 insertions(+), 2 deletions(-)

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2.34.1