Commit c50cbb05 authored by Ben Hutchings's avatar Ben Hutchings Committed by Ingo Molnar

cpu topology: always 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

[ From: Andrew Morton <akpm@linux-foundation.org>
  - fold now-duplicated code
  - fix layout
]
Signed-off-by: default avatarBen Hutchings <bhutchings@solarflare.com>
Cc: Vegard Nossum <vegard.nossum@gmail.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Chandra Seetharaman <sekharan@us.ibm.com>
Cc: Suresh Siddha <suresh.b.siddha@intel.com>
Cc: Mike Travis <travis@sgi.com>
Cc: Christoph Lameter <clameter@sgi.com>
Cc: John Hawkes <hawkes@sgi.com>
Cc: Zhang, Yanmin <yanmin.zhang@intel.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent aab2545f
......@@ -14,9 +14,8 @@ represent the thread siblings to cpu X in the same physical package;
To implement it in an architecture-neutral way, a new source file,
drivers/base/topology.c, is to export the 4 attributes.
If one architecture wants to support this feature, it just needs to
implement 4 defines, typically in file include/asm-XXX/topology.h.
The 4 defines are:
For an architecture to support this feature, it must define some of
these macros in include/asm-XXX/topology.h:
#define topology_physical_package_id(cpu)
#define topology_core_id(cpu)
#define topology_thread_siblings(cpu)
......@@ -25,17 +24,10 @@ The 4 defines are:
The type of **_id is int.
The type of siblings is cpumask_t.
To be consistent on all architectures, the 4 attributes should have
default values if their values are unavailable. Below is the rule.
1) physical_package_id: If cpu has no physical package id, -1 is the
default value.
2) core_id: If cpu doesn't support multi-core, its core id is 0.
3) thread_siblings: Just include itself, if the cpu doesn't support
HT/multi-thread.
4) core_siblings: Just include itself, if the cpu doesn't support
multi-core and HT/Multi-thread.
So be careful when declaring the 4 defines in include/asm-XXX/topology.h.
If an attribute isn't defined on an architecture, it won't be exported.
To be consistent on all architectures, include/linux/topology.h
provides default definitions for any of the above macros that are
not defined by include/asm-XXX/topology.h:
1) physical_package_id: -1
2) core_id: 0
3) thread_siblings: just the given CPU
4) core_siblings: just the given CPU
......@@ -59,60 +59,42 @@ static ssize_t show_cpumap(int type, cpumask_t *mask, char *buf)
static inline ssize_t show_##name(struct sys_device *dev, char *buf) \
{ \
unsigned int cpu = dev->id; \
return show_cpumap(0, &(topology_##name(cpu)), buf); \
cpumask_t siblings = topology_##name(cpu); \
return show_cpumap(0, &siblings, buf); \
}
#define define_siblings_show_list(name) \
static inline ssize_t show_##name##_list(struct sys_device *dev, char *buf) \
{ \
unsigned int cpu = dev->id; \
return show_cpumap(1, &(topology_##name(cpu)), buf); \
cpumask_t siblings = topology_##name(cpu); \
return show_cpumap(1, &siblings, buf); \
}
#define define_siblings_show_func(name) \
define_siblings_show_map(name); define_siblings_show_list(name)
#ifdef topology_physical_package_id
define_id_show_func(physical_package_id);
define_one_ro(physical_package_id);
#define ref_physical_package_id_attr &attr_physical_package_id.attr,
#else
#define ref_physical_package_id_attr
#endif
#ifdef topology_core_id
define_id_show_func(core_id);
define_one_ro(core_id);
#define ref_core_id_attr &attr_core_id.attr,
#else
#define ref_core_id_attr
#endif
#ifdef topology_thread_siblings
define_siblings_show_func(thread_siblings);
define_one_ro(thread_siblings);
define_one_ro(thread_siblings_list);
#define ref_thread_siblings_attr \
&attr_thread_siblings.attr, &attr_thread_siblings_list.attr,
#else
#define ref_thread_siblings_attr
#endif
#ifdef topology_core_siblings
define_siblings_show_func(core_siblings);
define_one_ro(core_siblings);
define_one_ro(core_siblings_list);
#define ref_core_siblings_attr \
&attr_core_siblings.attr, &attr_core_siblings_list.attr,
#else
#define ref_core_siblings_attr
#endif
static struct attribute *default_attrs[] = {
ref_physical_package_id_attr
ref_core_id_attr
ref_thread_siblings_attr
ref_core_siblings_attr
&attr_physical_package_id.attr,
&attr_core_id.attr,
&attr_thread_siblings.attr,
&attr_thread_siblings_list.attr,
&attr_core_siblings.attr,
&attr_core_siblings_list.attr,
NULL
};
......
......@@ -179,4 +179,17 @@ void arch_update_cpu_topology(void);
#endif
#endif /* CONFIG_NUMA */
#ifndef topology_physical_package_id
#define topology_physical_package_id(cpu) ((void)(cpu), -1)
#endif
#ifndef topology_core_id
#define topology_core_id(cpu) ((void)(cpu), 0)
#endif
#ifndef topology_thread_siblings
#define topology_thread_siblings(cpu) cpumask_of_cpu(cpu)
#endif
#ifndef topology_core_siblings
#define topology_core_siblings(cpu) cpumask_of_cpu(cpu)
#endif
#endif /* _LINUX_TOPOLOGY_H */
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