linux-kernel - Re: [PATCH v6 4/5] net: wan: fsl_qmc_hdlc: Add runtime timeslots changes support

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Date: Wed, 6 Mar 2024 16:43:11 +0100
From: Herve Codina <herve.codina@...tlin.com>
To: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>, Yury Norov
 <yury.norov@...il.com>
Cc: Vadim Fedorenko <vadim.fedorenko@...ux.dev>, "David S. Miller"
 <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>, Jakub Kicinski
 <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>, Rasmus Villemoes
 <linux@...musvillemoes.dk>, linux-kernel@...r.kernel.org,
 netdev@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org, Andrew Lunn
 <andrew@...n.ch>, Mark Brown <broonie@...nel.org>, Christophe Leroy
 <christophe.leroy@...roup.eu>, Thomas Petazzoni
 <thomas.petazzoni@...tlin.com>
Subject: Re: [PATCH v6 4/5] net: wan: fsl_qmc_hdlc: Add runtime timeslots
 changes support

Hi Andy, Yury,

On Wed, 6 Mar 2024 15:43:04 +0200
Andy Shevchenko <andriy.shevchenko@...ux.intel.com> wrote:

> On Wed, Mar 06, 2024 at 05:06:12AM -0800, Yury Norov wrote:
> > On Wed, Mar 06, 2024 at 09:07:20AM +0100, Herve Codina wrote:  
> 
> ...
> 
> > > +	DECLARE_BITMAP(ts_mask_avail, 64);
> > > +	DECLARE_BITMAP(ts_mask, 64);
> > > +	DECLARE_BITMAP(map, 64);  
> 
> 
> > > +	bitmap_from_u64(ts_mask_avail, ts_info->rx_ts_mask_avail);
> > > +	bitmap_from_u64(map, slot_map);  
> 
> > We've got a BITMAP_FROM_U64() for this:
> > 
> > 	DECLARE_BITMAP(ts_mask_avail, 64) = { BITMAP_FROM_U64(ts_info->rx_ts_mask_avail) };
> > 	DECLARE_BITMAP(map, 64) = { BITMAP_FROM_U64(slot_map) };  
> 
> This looks ugly. Can we rather provide a macro that does this under the hood?
> 
> Roughly:
> 
> #define DEFINE_BITMAP_64(name, src)				\
> 	DECLARE_BITMAP(name, 64) = { BITMAP_FROM_U64(src) }
> 

Well, the construction I used:
	DECLARE_BITMAP(foo, 64);
	...
	bitmap_from_u64(foo, init_value);
	...
can be found in several places in the kernel.

Having the DEFINE_BITMAP_64() macro can be a way to remove this
construction but I am not sure that this should be done in this
series.

IMHO, a specific series introducing the macro and updating pieces of
code in the kernel everywhere it is needed to replace this construction
would make much more sense.

Best regards,
Hervé