selftests: devlink_lib: Fix bouncing of netdevsim DEVLINK_DEV

In the commit referenced below, a check was added to devlink_lib that
asserts the existence of a devlink device referenced by $DEVLINK_DEV.
Unfortunately, several netdevsim tests point DEVLINK_DEV at a device that
does not exist at the time that devlink_lib is sourced. Thus these tests
spuriously fail.

Fix this by introducing an override. By setting DEVLINK_DEV to an empty
string, the user declares their intention to handle DEVLINK_DEV management
on their own.

In all netdevsim tests that use devlink_lib and set DEVLINK_DEV, set
instead an empty DEVLINK_DEV just before sourcing devlink_lib, and set it
to the correct value right afterwards.

Fixes: 557c4d2f ("selftests: devlink_lib: add check for devlink device existence")
Signed-off-by: Petr Machata <petrm@nvidia.com>
Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

tools/testing/selftests/drivers/net/netdevsim/devlink_trap.sh

@@ -24,13 +24,15 @@ ALL_TESTS="
 NETDEVSIM_PATH=/sys/bus/netdevsim/
 DEV_ADDR=1337
 DEV=netdevsim${DEV_ADDR}
-DEVLINK_DEV=netdevsim/${DEV}
 DEBUGFS_DIR=/sys/kernel/debug/netdevsim/$DEV/
 SLEEP_TIME=1
 NETDEV=""
 NUM_NETIFS=0
 source $lib_dir/lib.sh
+
+DEVLINK_DEV=
 source $lib_dir/devlink_lib.sh
+DEVLINK_DEV=netdevsim/${DEV}
 
 require_command udevadm
 

tools/testing/selftests/drivers/net/netdevsim/fib.sh

@@ -33,13 +33,15 @@ ALL_TESTS="
 NETDEVSIM_PATH=/sys/bus/netdevsim/
 DEV_ADDR=1337
 DEV=netdevsim${DEV_ADDR}
-DEVLINK_DEV=netdevsim/${DEV}
 SYSFS_NET_DIR=/sys/bus/netdevsim/devices/$DEV/net/
 NUM_NETIFS=0
 source $lib_dir/lib.sh
-source $lib_dir/devlink_lib.sh
 source $lib_dir/fib_offload_lib.sh
 
+DEVLINK_DEV=
+source $lib_dir/devlink_lib.sh
+DEVLINK_DEV=netdevsim/${DEV}
+
 ipv4_identical_routes()
 {
 	fib_ipv4_identical_routes_test "testns1"

tools/testing/selftests/drivers/net/netdevsim/nexthop.sh

@@ -44,12 +44,14 @@ ALL_TESTS="
 NETDEVSIM_PATH=/sys/bus/netdevsim/
 DEV_ADDR=1337
 DEV=netdevsim${DEV_ADDR}
-DEVLINK_DEV=netdevsim/${DEV}
 SYSFS_NET_DIR=/sys/bus/netdevsim/devices/$DEV/net/
 DEBUGFS_NET_DIR=/sys/kernel/debug/netdevsim/$DEV/
 NUM_NETIFS=0
 source $lib_dir/lib.sh
+
+DEVLINK_DEV=
 source $lib_dir/devlink_lib.sh
+DEVLINK_DEV=netdevsim/${DEV}
 
 nexthop_check()
 {

tools/testing/selftests/drivers/net/netdevsim/psample.sh

@@ -14,13 +14,15 @@ ALL_TESTS="
 NETDEVSIM_PATH=/sys/bus/netdevsim/
 DEV_ADDR=1337
 DEV=netdevsim${DEV_ADDR}
-DEVLINK_DEV=netdevsim/${DEV}
 SYSFS_NET_DIR=/sys/bus/netdevsim/devices/$DEV/net/
 PSAMPLE_DIR=/sys/kernel/debug/netdevsim/$DEV/psample/
 CAPTURE_FILE=$(mktemp)
 NUM_NETIFS=0
 source $lib_dir/lib.sh
+
+DEVLINK_DEV=
 source $lib_dir/devlink_lib.sh
+DEVLINK_DEV=netdevsim/${DEV}
 
 # Available at https://github.com/Mellanox/libpsample
 require_command psample

tools/testing/selftests/net/forwarding/devlink_lib.sh

@@ -18,7 +18,7 @@ if [[ ! -v DEVLINK_DEV ]]; then
 
 	DEVLINK_VIDDID=$(lspci -s $(echo $DEVLINK_DEV | cut -d"/" -f2) \
 			 -n | cut -d" " -f3)
-else
+elif [[ ! -z "$DEVLINK_DEV" ]]; then
 	devlink dev show $DEVLINK_DEV &> /dev/null
 	if [ $? -ne 0 ]; then
 		echo "SKIP: devlink device \"$DEVLINK_DEV\" not found"