On Tue, Jul 24, 2018 at 02:37:11PM -0600, Jason Gunthorpe wrote:
> This clearly indicates that the input is a bitwise combination of values
> in an enum, and identifies which enum contains the definition of the bits.
>
> Special accessors are provided that handle the mandatory validation of the
> allowed bits and enforce the correct type for bitwise flags.
>
> If we had introduced this at the start then the kabi would have uniformly
> used u64 data to pass flags, however today there is a mixture of u64 and
> u32 flags. All places are converted to accept both sizes and the accessor
> fixes it. This allows all existing flags to grow to u64 in future without
> any hassle.
>
> Finally all flags are, by definition, optional. If flags are not passed
> the accessor does not fail, but provides a value of zero.
>
> Signed-off-by: Jason Gunthorpe <jgg@xxxxxxxxxxxx>
> ---
....
> +#define UVERBS_ATTR_FLAGS_IN(_attr_id, _enum_type, ...) \
> + UVERBS_ATTR_PTR_IN( \
> + _attr_id, \
> + UVERBS_ATTR_SIZE(sizeof(_enum_type) * 0 + sizeof(u32), \
^^^^^
What did you mean by " * 0"?
> + sizeof(u64)), \
> + __VA_ARGS__)
> +
Thanks
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