Check if the netdev list is empty and create veth pair to be used for
feature on/off testing.
Remove the veth pair after testing is complete.

Signed-off-by: Abhinav Jain <jain.abhinav177@gmail.com>
---
 tools/testing/selftests/net/netdevice.sh | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/tools/testing/selftests/net/netdevice.sh b/tools/testing/selftests/net/netdevice.sh
index e3afcb424710..0c32950fdd17 100755
--- a/tools/testing/selftests/net/netdevice.sh
+++ b/tools/testing/selftests/net/netdevice.sh
@@ -129,6 +129,7 @@ kci_netdev_ethtool()
 
 	kci_netdev_ethtool_test 74 'dump' "ethtool -d $netdev"
 	kci_netdev_ethtool_test 94 'stats' "ethtool -S $netdev"
+
 	return 0
 }
 
@@ -196,10 +197,25 @@ if [ ! -e "$TMP_LIST_NETDEV" ];then
 fi
 
 ip link show |grep '^[0-9]' | grep -oE '[[:space:]].*eth[0-9]*:|[[:space:]].*enp[0-9]s[0-9]:' | cut -d\  -f2 | cut -d: -f1> "$TMP_LIST_NETDEV"
+
+if [ ! -s "$TMP_LIST_NETDEV" ]; then
+	echo "No valid network device found, creating veth pair"
+	ip link add veth0 type veth peer name veth1
+	echo "veth0" > "$TMP_LIST_NETDEV"
+	echo "veth1" >> "$TMP_LIST_NETDEV"
+	veth_created=1
+fi
+
 while read netdev
 do
 	kci_test_netdev "$netdev"
 done < "$TMP_LIST_NETDEV"
 
+#clean up veth interface pair if it was created
+if [ "$veth_created" ]; then
+	ip link delete veth0
+	echo "Removed veth pair"
+fi
+
 rm "$TMP_LIST_NETDEV"
 exit 0
-- 
2.34.1

On Mon, 19 Aug 2024 17:42:33 +0530 Abhinav Jain wrote:
> +	echo "veth0" > "$TMP_LIST_NETDEV"
> +	echo "veth1" >> "$TMP_LIST_NETDEV"

Why test both ends? 
Aren't we going to do the same exact test twice?

On Tue, 20 Aug 2024 16:50:06 -0700, Jakub Kicinski wrote:
> On Mon, 19 Aug 2024 17:42:33 +0530 Abhinav Jain wrote:
> > +	echo "veth0" > "$TMP_LIST_NETDEV"
> > +	echo "veth1" >> "$TMP_LIST_NETDEV"
>
> Why test both ends? 
> Aren't we going to do the same exact test twice?

I presumed that we would want to run the interface up/down, setup and ethtool tests on both veth.
If this is not required, should I submit a v9 removing veth1 from the temp list?

Also, while sending v9, do I add the Review tag from Simon or it has to be reviewed again?

On Wed, 21 Aug 2024 18:07:33 +0530 Abhinav Jain wrote:
> I presumed that we would want to run the interface up/down, setup and ethtool tests on both veth.
> If this is not required, should I submit a v9 removing veth1 from the temp list?

Yes, please.

> Also, while sending v9, do I add the Review tag from Simon or it has to be reviewed again?

Yes, you should add the review tags

On Wed, 21 Aug 2024 09:00:41 -0700, Jakub Kicinski wrote:
>> I presumed that we would want to run the interface up/down, setup and ethtool tests on both veth.
>> If this is not required, should I submit a v9 removing veth1 from the temp list?
>
> Yes, please.
>
>> Also, while sending v9, do I add the Review tag from Simon or it has to be reviewed again?
> 
> Yes, you should add the review tags

Thanks for confirming, I have sent v9 accordingly:
https://lore.kernel.org/all/20240821171903.118324-1-jain.abhinav177@gmail.com

Please review, thanks again.

On Mon, Aug 19, 2024 at 05:42:33PM +0530, Abhinav Jain wrote:
> Check if the netdev list is empty and create veth pair to be used for
> feature on/off testing.
> Remove the veth pair after testing is complete.
> 
> Signed-off-by: Abhinav Jain <jain.abhinav177@gmail.com>

Reviewed-by: Simon Horman <horms@kernel.org>