Re: [PATCH v2 2/2] selftests: ptp: treat unsupported PHC operations as skip

[Simon Horman]

On Mon, Jan 26, 2026 at 02:15:32PM +0800, Junjie Cao wrote:
> Some PTP hardware clock (PHC) devices may return -EOPNOTSUPP for
> operations like settime, adjtime, or adjfreq. This commonly occurs
> with timestamp-only PHC implementations that don't support full clock
> control.
> 
> For background, syzbot previously exposed a crash risk when PTP clock
> drivers lacked required callbacks[1]. Subsequent work[2] made callback
> presence a registration requirement. As a result, some drivers (like
> iwlwifi MVM/MLD[3]) now provide stub callbacks that return -EOPNOTSUPP
> for unsupported operations.
> 
> When phc_ctl encounters such devices, the "Operation not supported"
> error should be treated as a skip (device limitation) rather than a
> test failure. This patch:
> - Adds [SKIP] output handling in log_test()
> - Detects "Operation not supported" from phc_ctl and returns ksft_skip
> - Returns ksft_skip if all tests are skipped, preventing false-positive
>   results when testing timestamp-only PHC implementations
> 
> Link: https://lore.kernel.org/netdev/20251028043216.1971292-1-junjie.cao@xxxxxxxxx/ [1]
> Link: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=dfb073d32cac [2]
> Link: https://lore.kernel.org/netdev/20251204123204.9316-1-ziyao@xxxxxxxxxxx/ [3]
> Signed-off-by: Junjie Cao <junjie.cao@xxxxxxxxx>


Reviewed-by: Simon Horman <horms@xxxxxxxxxx>