netdev - Re: [PATCH] nfp: convert nfp_eth_set_bit

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Message-ID: <20171004162550.20edf18c@cakuba.netronome.com>
Date:   Wed, 4 Oct 2017 16:25:50 -0700
From:   Jakub Kicinski <jakub.kicinski@...ronome.com>
To:     Matthias Kaehlcke <mka@...omium.org>
Cc:     Joe Perches <joe@...ches.com>,
        "David S . Miller" <davem@...emloft.net>,
        Simon Horman <simon.horman@...ronome.com>,
        Dirk van der Merwe <dirk.vandermerwe@...ronome.com>,
        oss-drivers@...ronome.com, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Renato Golin <renato.golin@...aro.org>,
        Manoj Gupta <manojgupta@...omium.org>,
        Guenter Roeck <groeck@...omium.org>,
        Doug Anderson <dianders@...omium.org>
Subject: Re: [PATCH] nfp: convert nfp_eth_set_bit_config() into a macro

On Wed, 4 Oct 2017 16:16:49 -0700, Matthias Kaehlcke wrote:
> > > 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.  
> > 
> > The reason the __BF_FIELD_CHECK refuses to compile non-constant masks
> > is that it will require runtime ffs on the mask, which is potentially
> > costly.  I would also feel quite stupid adding those macros to the nfp
> > driver, given that I specifically created the bitfield.h header to not
> > have to reimplement these in every driver I write/maintain.  
> 
> That make sense, thanks for providing more context.
> 
> > Can you please test the patch I provided in the other reply?  
> 
> With this patch there are no errors when building the kernel with
> clang.

Cool, thanks for checking!  I will run it through full tests and queue
for upstreaming :)