[PATCH] node hotplug: register cpu: remove node struct

With Goto-san's patch, we can add new pgdat/node at runtime.  I'm now
considering node-hot-add with cpu + memory on ACPI.

I found acpi container, which describes node, could evaluate cpu before
memory. This means cpu-hot-add occurs before memory hot add.

In most part, cpu-hot-add doesn't depend on node hot add.  But register_cpu(),
which creates symbolic link from node to cpu, requires that node should be
onlined before register_cpu().  When a node is onlined, its pgdat should be
there.

This patch-set holds off creating symbolic link from node to cpu
until node is onlined.

This removes node arguments from register_cpu().

Now, register_cpu() requires 'struct node' as its argument.  But the array of
struct node is now unified in driver/base/node.c now (By Goto's node hotplug
patch).  We can get struct node in generic way.  So, this argument is not
necessary now.

This patch also guarantees add cpu under node only when node is onlined.  It
is necessary for node-hot-add vs.  cpu-hot-add patch following this.

Moreover, register_cpu calculates cpu->node_id by cpu_to_node() without regard
to its 'struct node *root' argument.  This patch removes it.

Also modify callers of register_cpu()/unregister_cpu, whose args are changed
by register-cpu-remove-node-struct patch.

[Brice.Goglin@ens-lyon.org: fix it]
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Yasunori Goto <y-goto@jp.fujitsu.com>
Cc: Ashok Raj <ashok.raj@intel.com>
Cc: Dave Hansen <haveblue@us.ibm.com>
Signed-off-by: Brice Goglin <Brice.Goglin@ens-lyon.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

2 files changed, 2 insertions, 12 deletions

diff --git a/arch/powerpc/kernel/setup_32.c b/arch/powerpc/kernel/setup_32.c
index e5a44812441a..0932a62a1c96 100644
--- a/arch/powerpc/kernel/setup_32.c
+++ b/arch/powerpc/kernel/setup_32.c
@@ -215,7 +215,7 @@ int __init ppc_init(void)
 
         /* register CPU devices */
         for_each_possible_cpu(i)
-                register_cpu(&cpu_devices[i], i, NULL);
+                register_cpu(&cpu_devices[i], i);
 
         /* call platform init */
         if (ppc_md.init != NULL) {
diff --git a/arch/powerpc/kernel/sysfs.c b/arch/powerpc/kernel/sysfs.c
index 338491d1604a..412ad00e222d 100644
--- a/arch/powerpc/kernel/sysfs.c
+++ b/arch/powerpc/kernel/sysfs.c
@@ -348,23 +348,13 @@ static SYSDEV_ATTR(physical_id, 0444, show_physical_id, NULL);
 static int __init topology_init(void)
 {
         int cpu;
-        struct node *parent = NULL;
 
         register_nodes();
-
         register_cpu_notifier(&sysfs_cpu_nb);
 
         for_each_possible_cpu(cpu) {
                 struct cpu *c = &per_cpu(cpu_devices, cpu);
 
-#ifdef CONFIG_NUMA
-                /* The node to which a cpu belongs can't be known
-                 * until the cpu is made present.
-                 */
-                parent = NULL;
-                if (cpu_present(cpu))
-                        parent = &node_devices[cpu_to_node(cpu)];
-#endif
                 /*
                  * For now, we just see if the system supports making
                  * the RTAS calls for CPU hotplug.  But, there may be a
@@ -376,7 +366,7 @@ static int __init topology_init(void)
                         c->no_control = 1;
 
                 if (cpu_online(cpu) || (c->no_control == 0)) {
-                        register_cpu(c, cpu, parent);
+                        register_cpu(c, cpu);
 
                         sysdev_create_file(&c->sysdev, &attr_physical_id);
                 }