selftests: forwarding: hw_stats_l3: Set addrgenmode in a separate step

Setting the IPv6 address generation mode of a net device during its
creation never worked, but after commit b0ad3c179059 ("rtnetlink: call
validate_linkmsg in rtnl_create_link") it explicitly fails [1]. The
failure is caused by the fact that validate_linkmsg() is called before
the net device is registered, when it still does not have an 'inet6_dev'.

Likewise, raising the net device before setting the address generation
mode is meaningless, because by the time the mode is set, the address
has already been generated.

Therefore, fix the test to first create the net device, then set its
IPv6 address generation mode and finally bring it up.

[1]
# ip link add name mydev addrgenmode eui64 type dummy
RTNETLINK answers: Address family not supported by protocol

Fixes: ba95e7930957 ("selftests: forwarding: hw_stats_l3: Add a new test")
Signed-off-by: Danielle Ratson <danieller@nvidia.com>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: Petr Machata <petrm@nvidia.com>
Link: https://lore.kernel.org/r/f3b05d85b2bc0c3d6168fe8f7207c6c8365703db.1686580046.git.petrm@nvidia.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

selftests: forwarding: hw_stats_l3: Detect failure to install counters

Running this test makes little sense if the enabled l3_stats are not
actually reported as "used". This can signify a failure of a driver to
install the necessary counters, or simply lack of support for enabling
in-HW counters on a given netdevice. It is generally impossible to tell
from the outside which it is. But more likely than not, if somebody is
running this on veth pairs, they do not intend to actually test that a
certain piece of HW can install in-HW counters for the veth. It is more
likely they are e.g. running the test by mistake.

Therefore detect that the counter has not been actually installed. In that
case, if the netdevice is one end of a veth pair, SKIP. Otherwise FAIL.

Suggested-by: Hangbin Liu <liuhangbin@gmail.com>
Signed-off-by: Petr Machata <petrm@nvidia.com>
Reviewed-by: Danielle Ratson <danieller@nvidia.com>
Tested-by: Hangbin Liu <liuhangbin@gmail.com>
Link: https://lore.kernel.org/r/a86817961903cca5cb0aebf2b2a06294b8aa7dea.1680704172.git.petrm@nvidia.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

selftests: lib: Add a generic helper for obtaining HW stats

The function get_l3_stats() from the test hw_stats_l3.sh will be useful for
any test that wishes to work with L3 stats. Furthermore, it is easy to
generalize to other HW stats suites (for when such are added). Therefore,
move the code to lib.sh, rewrite it to have the same interface as the other
stats-collecting functions, and generalize to take the name of the HW stats
suite to collect as an argument.

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>

selftests: forwarding: hw_stats_l3: Add a new test

Add a test that verifies operation of L3 HW statistics.

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>