Re: [PATCH net-next v2] net: generalize calculation of skb extensions length

[Simon Horman]

On Wed, Aug 23, 2023 at 11:28:38AM +0200, Thomas Weißschuh wrote:
> Remove the necessity to modify skb_ext_total_length() when new extension
> types are added.
> Also reduces the line count a bit.
> 
> With optimizations enabled the function is folded down to the same
> constant value as before during compilation.
> This has been validated on x86 with GCC 6.5.0 and 13.2.1.
> Also a similar construct has been validated on godbolt.org with GCC 5.1.
> In any case the compiler has to be able to evaluate the construct at
> compile-time for the BUILD_BUG_ON() in skb_extensions_init().
> 
> Even if not evaluated at compile-time this function would only ever
> be executed once at run-time, so the overhead would be very minuscule.
> 
> Signed-off-by: Thomas Weißschuh <linux@xxxxxxxxxxxxxx>

Reviewed-by: Simon Horman <horms@xxxxxxxxxx>