ACK: [SRU][J][PATCH 0/2] selftests: net: veth: fix compatibility with older ethtool versions (LP: #2136734)

[Juerg Haefliger]

> BugLink: https://bugs.launchpad.net/bugs/2136734
> 
> [ Impact ]
> 
> The veth.sh selftest fails on Focal systems running 5.15 hwe kernel
> due to incompatibilities with older ethtool version shipped in Focal.
> 
> Two specific failures occur:
> 1. The test command "ethtool -K veth$DST generic-receive-offload on"
>    fails with "ethtool: bad command line argument(s)" because ethtool 5.4
>    does not recognize the long form feature name with the -K option.
> 2. The chk_channels() function incorrectly reports failures for combined
>    channels because ethtool 5.4 outputs '0' for unsupported channels while
>    the test expects 'n/a'.
> 
> These failures occur even when the underlying kernel functionality being
> tested works correctly, causing false negatives in the test suite.
> 
> [ Fix ]
> 
> Use the short form 'gro' instead of 'generic-receive-offload' when
> setting features with ethtool -K. The short form is compatible with
> both old and new ethtool versions, while the long form only works with
> newer versions for the -K operation.
> 
> Modify the chk_channels() function to accept both 'n/a' and '0' as valid
> values for unsupported combined channels. This accommodates the
> different output formats between ethtool versions while maintaining the
> correct validation logic.
> 
> Both fixes are purely compatibility changes that do not alter the test
> logic or the kernel functionality being tested.
> 
> [ Test Plan ]
> 
> Test ubuntu_kselftest_net net:veth.sh on both Jammy 5.15 and Focal 5.15 kernels.
> The expected output is the following:
> 
> # selftests: net: veth.sh
> # default - gro flag ok
> # - peer gro flag ok
> # - tso flag ok
> # - peer tso flag ok
> # - aggregation ok
> # - aggregation with TSO off ok
> # with gro on - gro flag ok
> # - peer gro flag ok
> # - tso flag ok
> # - peer tso flag ok
> # - aggregation with TSO off ok
> # gro vs xdp while down - gro flag on ok
> # - after down ok
> # - after xdp off ok
> # - after up ok
> # - after peer xdp ok
> # default channels ok
> # with gro enabled on link down - gro flag ok
> # - peer gro flag ok
> # - tso flag ok
> # - peer tso flag ok
> # - aggregation with TSO off ok
> # setting tx channels ok
> # setting both rx and tx channels ok
> # bad setting: combined channels ok
> # setting invalid channels nr ok
> # bad setting: XDP with RX nr less than TX ok
> # bad setting: reducing RX nr below peer TX with XDP set ok
> # bad setting: increasing peer TX nr above RX with XDP set ok
> # setting invalid channels nr ok
> # with xdp attached - gro flag ok
> # - peer gro flag ok
> # - tso flag ok
> # - peer tso flag ok
> # - no aggregation ok
> # - gro flag with GRO on ok
> # - aggregation ok
> # - after dev off, flag ok
> # - peer flag ok
> # - after gro on xdp off, gro flag ok
> # - peer gro flag ok
> # - tso flag ok
> # - peer tso flag ok
> # decreasing tx channels with device down ok
> # - aggregation ok
> # increasing tx channels with device down ok
> # aggregation again with default and TSO off ok
> ok 7 selftests: net: veth.sh
> 
> [ Regression Potential ]
> 
> The patchset only modify the selftest script and do not change any
> kernel code. The changes improve compatibility with different ethtool
> versions by using universally supported feature names and accepting
> multiple valid output formats. In case of a regression, it would only
> affect test execution, not kernel functionality.
> 
> [ Other Info ]
> 
> The bug affects all Focal's 5.15 kernels.
> In order to fix them all the patchset has been submitted for Jammy.
> 
> Massimiliano Pellizzer (2):
>   selftests: net: veth: use short form gro for ethtool -K
>   selftests: net: veth: accept 0 for unsupported combined channels
> 
>  tools/testing/selftests/net/veth.sh | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
> 

Acked-by: Juerg Haefliger <juerg.haefliger at canonical.com>

...Juerg
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