Subject: Re: [PATCH] nfp: convert nfp_eth_set_bit_config() into a macro

From: Matthias Kaehlcke <[email-masked]>
Date: Wed, 4 Oct 2017 11:49:57 -0700

Hi Joe,

El Wed, Oct 04, 2017 at 11:07:19AM -0700 Joe Perches ha dit:

> On Tue, 2017-10-03 at 13:05 -0700, Matthias Kaehlcke wrote:
> > nfp_eth_set_bit_config() is marked as __always_inline to allow gcc to
> > identify the 'mask' parameter as known to be constant at compile time,
> > which is required to use the FIELD_GET() macro.
> > 
> > The forced inlining does the trick for gcc, but for kernel builds with
> > clang it results in undefined symbols:
> 
> Can't you use local different FIELD_PREP/FIELD_GET macros
> with a different name without the BUILD_BUG tests?
> 
> i.e.:
> 
> #define NFP_FIELD_PREP(_mask, _val)				\
> ({								\
> 	((typeof(_mask))(_val) << __bf_shf(_mask)) & (_mask);	\
> })
> 
> #define NFP_FIELD_GET(_mask, _reg)				\
> ({								\
> 	(typeof(_mask))(((_reg) & (_mask)) >> __bf_shf(_mask));	\
> })
> 
> Then the __always_inline can be removed from
> nfp_eth_set_bit_config too.

Thanks for the suggestion. This seems a viable alternative if David
and the NFP owners can live without the extra checking provided by
__BF_FIELD_CHECK.