Re: [PATCH v2 5/7] doc: add some more documentation on bitmasks

[Florian Westphal <fw@strlen.de>]

Christoph Anton Mitterer <mail@christoph.anton.mitterer.name> wrote:
> Signed-off-by: Christoph Anton Mitterer <mail@christoph.anton.mitterer.name>
> ---
>  doc/data-types.txt | 16 ++++++++++++++++
>  1 file changed, 16 insertions(+)
> 
> diff --git a/doc/data-types.txt b/doc/data-types.txt
> index 18af266a..47a0d25a 100644
> --- a/doc/data-types.txt
> +++ b/doc/data-types.txt
> @@ -26,6 +26,22 @@ integer
>  
>  The bitmask type (*bitmask*) is used for bitmasks.
>  
> +In expressions the bits of a bitmask may be specified as *'bit'[,'bit']...* with
> +'bit' being the value of the bit or a pre-defined symbolic constant, if any (for
> +example *ct state*’s bit 0x1 has the symbolic constant `new`).

[..]

> +The syntax *'expression' 'value' / 'mask'* is identical to
> +*'expression' and 'mask' == 'value'*.
> +For example `tcp flags syn,ack / syn,ack,fin,rst` is the same as
> +`tcp flags and (syn|ack|fin|rst) == syn|ack`.
> +
> +It should further be noted that *'expression' 'bit'[,'bit']...* is not the same
> +as *'expression' {'bit'[,'bit']...}*.

Maybe add another sentence, something like:
Note that *'expression' 'bit'[,'bit']...* is not the same
as *'expression' {'bit'[,'bit']...}*.  The latter constitutes
a lookup in an anonymous set and will match only if the set
contains an exact match.

And/or maybe also include an example involving tcp flags to make it clear.

Do you  think a reference to "nft describe tcp flags" should be made?
There is normally no reason to muck with the raw values (or even a need
to know that new is 0x1).

This patch LGTM otherwise.