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: Ben 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: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 10 insertions, 28 deletions

diff --git a/drivers/base/topology.c b/drivers/base/topology.c
index fdf4044d2e74..24d29a9fc25b 100644
--- a/drivers/base/topology.c
+++ b/drivers/base/topology.c
@@ -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
 };