IB/mlx5: Allow future extension of libmlx5 input data
Current check requests that new fields in struct mlx5_ib_alloc_ucontext_req_v2 that are not known to the driver be zero. This was introduced so new libraries passing additional information to the kernel through struct mlx5_ib_alloc_ucontext_req_v2 will be notified by old kernels that do not support their request by failing the operation. This schecme is problematic since it requires libmlx5 to issue the requests with descending input size for struct mlx5_ib_alloc_ucontext_req_v2. To avoid this, we require that new features that will obey the following rules: If the feature requires one or more fields in the response and the at least one of the fields can be encoded such that a zero value means the kernel ignored the request then this field will provide the indication to the library. If no response is required or if zero is a valid response, a new field should be added that indicates to the library whether its request was processed. Fixes: b368d7cb ('IB/mlx5: Add hca_core_clock_offset to udata in init_ucontext') Signed-off-by: Eli Cohen <eli@mellanox.com> Reviewed-by: Matan Barak <matanb@mellanox.com> Signed-off-by: Leon Romanovsky <leon@kernel.org> Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>
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