linux-kernel - Re: [PATCH] cputopology: Always define CPU topology information [4th try]

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Message-Id: <20080604214715.bbebe325.akpm@linux-foundation.org>
Date:	Wed, 4 Jun 2008 21:47:15 -0700
From:	Andrew Morton <akpm@...ux-foundation.org>
To:	Ben Hutchings <bhutchings@...arflare.com>
Cc:	linux-kernel@...r.kernel.org, Ingo Molnar <mingo@...e.hu>,
	Vegard Nossum <vegard.nossum@...il.com>
Subject: Re: [PATCH] cputopology: Always define CPU topology information
 [4th try]

On Wed, 4 Jun 2008 16:44:56 +0100 Ben Hutchings <bhutchings@...arflare.com> wrote:

> Not all architectures and configurations define CPU topology information.
> This can result in an empty topology directory in sysfs, and requires
> in-kernel users to protect all uses with #ifdef - see
> <http://marc.info/?l=linux-netdev&m=120639033904472&w=2>.
> 
> The documentation of CPU topology specifies what the defaults should be
> if only partial information is available from the hardware.  So we can
> provide these defaults as a fallback.
> 
> This patch:
> 
> - Adds default definitions of the 4 topology macros to <linux/topology.h>
> - Changes drivers/base/topology.c to use the topology macros unconditionally
>   and to cope with definitions that aren't lvalues
> - Updates documentation accordingly

See, this is what I meant.  After your patch we have:

#ifdef arch_provides_topology_pointers
#define define_siblings_show_map(name)					\
static ssize_t show_##name(struct sys_device *dev, char *buf)	\
{									\
	unsigned int cpu = dev->id;					\
	cpumask_t siblings = topology_##name(cpu);			\
	return show_cpumap(0, &siblings, buf);				\
}

#define define_siblings_show_list(name)					\
static ssize_t show_##name##_list(struct sys_device *dev, char *buf) \
{									\
	unsigned int cpu = dev->id;					\
	cpumask_t siblings = topology_##name(cpu);			\
	return show_cpumap(1, &siblings, buf);				\
}

#else
#define define_siblings_show_map(name)					\
static ssize_t show_##name(struct sys_device *dev, char *buf)	\
{									\
	unsigned int cpu = dev->id;					\
	cpumask_t mask = topology_##name(cpu);				\
	return show_cpumap(0, &mask, buf);				\
}

#define define_siblings_show_list(name)					\
static ssize_t show_##name##_list(struct sys_device *dev, char *buf) \
{									\
	unsigned int cpu = dev->id;					\
	cpumask_t mask = topology_##name(cpu);				\
	return show_cpumap(1, &mask, buf);				\
}
#endif

they're the same!
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