Re: [PATCH] mask ADT: new mask.h file [2/22]

From: Rusty Russell <rusty@rustcorp.com.au>
To: Paul Jackson <pj@sgi.com>
Cc: lkml - Kernel Mailing List <linux-kernel@vger.kernel.org>,
	mbligh@aracnet.com, Andrew Morton <akpm@osdl.org>,
	wli@holomorphy.com, colpatch@us.ibm.com
Subject: Re: [PATCH] mask ADT: new mask.h file [2/22]
Date: Wed, 07 Apr 2004 10:02:13 +1000	[thread overview]
Message-ID: <1081255616.28514.72.camel@bach> (raw)
In-Reply-To: <20040406034055.1dbe2eac.pj@sgi.com>

On Tue, 2004-04-06 at 20:40, Paul Jackson wrote:
> Rusty - thank-you very much for your constructive feedback so far.
> 
> Seems to me that we are in agreement that slimming down the
> internals of cpumask_t is worth proceeding with, but not on possible
> changes to the cpumask API seen by the rest of the kernel.

OK, cool.  We can have that debate later.

> static inline void bitmap_and(unsigned long *d, const unsigned long *s1,
> 			const unsigned long *s2, int nbits)
> {
> 	if (nbits <= BITS_PER_LONG)
> 		d[0] = s1[0] & s2[0];
> 	else
> 		_bitmap_and(d, s1, s2, nbits);
> }

Two suggestions:
1) I think you only want the fastpath when it's eliminated by the
compiler, so perhaps:
	if (__builtin_constant_p(nbits) && nbits <= BITS_PER_LONG)

2) The normal kernel naming scheme is two underscores (__bitmap_and),
probably because it's clearer visually.

Thanks,
Rusty.
-- 
Anyone who quotes me in their signature is an idiot -- Rusty Russell