[PATCH] Register sysfs file for hotplugged new node

When new node becomes enable by hot-add, new sysfs file must be created for
new node.  So, if new node is enabled by add_memory(), register_one_node() is
called to create it.  In addition, I386's arch_register_node() and a part of
register_nodes() of powerpc are consolidated to register_one_node() as a
generic_code().

This is tested by Tiger4(IPF) with node hot-plug emulation.

Signed-off-by: Keiichiro Tokunaga <tokuanga.keiich@jp.fujitsu.com>
Signed-off-by: Yasunori Goto <y-goto@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

8 files changed, 48 insertions, 63 deletions

diff --git a/arch/i386/kernel/topology.c b/arch/i386/kernel/topology.c
index 296355292c7c..1eecc2e1bd4b 100644
--- a/arch/i386/kernel/topology.c
+++ b/arch/i386/kernel/topology.c
@@ -38,7 +38,7 @@ int arch_register_cpu(int num){
 #ifdef CONFIG_NUMA
         int node = cpu_to_node(num);
         if (node_online(node))
-                parent = &node_devices[node].node;
+                parent = &node_devices[parent_node(node)];
 #endif /* CONFIG_NUMA */
 
         /*
@@ -61,7 +61,7 @@ void arch_unregister_cpu(int num) {
 #ifdef CONFIG_NUMA
         int node = cpu_to_node(num);
         if (node_online(node))
-                parent = &node_devices[node].node;
+                parent = &node_devices[parent_node(node)];
 #endif /* CONFIG_NUMA */
 
         return unregister_cpu(&cpu_devices[num].cpu, parent);
@@ -74,16 +74,13 @@ EXPORT_SYMBOL(arch_unregister_cpu);
 
 #ifdef CONFIG_NUMA
 #include <linux/mmzone.h>
-#include <asm/node.h>
-
-struct i386_node node_devices[MAX_NUMNODES];
 
 static int __init topology_init(void)
 {
         int i;
 
         for_each_online_node(i)
-                arch_register_node(i);
+                register_one_node(i);
 
         for_each_present_cpu(i)
                 arch_register_cpu(i);
diff --git a/arch/ia64/kernel/topology.c b/arch/ia64/kernel/topology.c
index 879edb51d1e0..42cb05bdc680 100644
--- a/arch/ia64/kernel/topology.c
+++ b/arch/ia64/kernel/topology.c
@@ -26,9 +26,6 @@
 #include <asm/numa.h>
 #include <asm/cpu.h>
 
-#ifdef CONFIG_NUMA
-static struct node *sysfs_nodes;
-#endif
 static struct ia64_cpu *sysfs_cpus;
 
 int arch_register_cpu(int num)
@@ -36,7 +33,7 @@ int arch_register_cpu(int num)
         struct node *parent = NULL;
         
 #ifdef CONFIG_NUMA
-        parent = &sysfs_nodes[cpu_to_node(num)];
+        parent = &node_devices[cpu_to_node(num)];
 #endif /* CONFIG_NUMA */
 
 #if defined (CONFIG_ACPI) && defined (CONFIG_HOTPLUG_CPU)
@@ -59,7 +56,7 @@ void arch_unregister_cpu(int num)
 
 #ifdef CONFIG_NUMA
         int node = cpu_to_node(num);
-        parent = &sysfs_nodes[node];
+        parent = &node_devices[node];
 #endif /* CONFIG_NUMA */
 
         return unregister_cpu(&sysfs_cpus[num].cpu, parent);
@@ -74,17 +71,11 @@ static int __init topology_init(void)
         int i, err = 0;
 
 #ifdef CONFIG_NUMA
-        sysfs_nodes = kzalloc(sizeof(struct node) * MAX_NUMNODES, GFP_KERNEL);
-        if (!sysfs_nodes) {
-                err = -ENOMEM;
-                goto out;
-        }
-
         /*
          * MCD - Do we want to register all ONLINE nodes, or all POSSIBLE nodes?
          */
         for_each_online_node(i) {
-                if ((err = register_node(&sysfs_nodes[i], i, 0)))
+                if ((err = register_one_node(i)))
                         goto out;
         }
 #endif
diff --git a/arch/powerpc/kernel/sysfs.c b/arch/powerpc/kernel/sysfs.c
index 5bc2585c8036..338491d1604a 100644
--- a/arch/powerpc/kernel/sysfs.c
+++ b/arch/powerpc/kernel/sysfs.c
@@ -304,23 +304,12 @@ static struct notifier_block sysfs_cpu_nb = {
 /* NUMA stuff */
 
 #ifdef CONFIG_NUMA
-static struct node node_devices[MAX_NUMNODES];
-
 static void register_nodes(void)
 {
         int i;
 
-        for (i = 0; i < MAX_NUMNODES; i++) {
-                if (node_online(i)) {
-                        int p_node = parent_node(i);
-                        struct node *parent = NULL;
-
-                        if (p_node != i)
-                                parent = &node_devices[p_node];
-
-                        register_node(&node_devices[i], i, parent);
-                }
-        }
+        for (i = 0; i < MAX_NUMNODES; i++)
+                register_one_node(i);
 }
 
 int sysfs_add_device_to_node(struct sys_device *dev, int nid)
diff --git a/drivers/base/node.c b/drivers/base/node.c
index c80c3aeed004..cbd0f62b4870 100644
--- a/drivers/base/node.c
+++ b/drivers/base/node.c
@@ -190,6 +190,31 @@ void unregister_node(struct node *node)
         sysdev_unregister(&node->sysdev);
 }
 
+struct node node_devices[MAX_NUMNODES];
+
+int register_one_node(int nid)
+{
+        int error = 0;
+
+        if (node_online(nid)) {
+                int p_node = parent_node(nid);
+                struct node *parent = NULL;
+
+                if (p_node != nid)
+                        parent = &node_devices[p_node];
+
+                error = register_node(&node_devices[nid], nid, parent);
+        }
+
+        return error;
+
+}
+
+void unregister_one_node(int nid)
+{
+        unregister_node(&node_devices[nid]);
+}
+
 static int __init register_node_type(void)
 {
         return sysdev_class_register(&node_class);
diff --git a/include/asm-i386/cpu.h b/include/asm-i386/cpu.h
index e7252c216ca8..b1bc7b1b64b0 100644
--- a/include/asm-i386/cpu.h
+++ b/include/asm-i386/cpu.h
@@ -7,8 +7,6 @@
 #include <linux/nodemask.h>
 #include <linux/percpu.h>
 
-#include <asm/node.h>
-
 struct i386_cpu {
         struct cpu cpu;
 };
diff --git a/include/asm-i386/node.h b/include/asm-i386/node.h
deleted file mode 100644
index e13c6ffa72ae..000000000000
--- a/include/asm-i386/node.h
+++ /dev/null
@@ -1,29 +0,0 @@
-#ifndef _ASM_I386_NODE_H_
-#define _ASM_I386_NODE_H_
-
-#include <linux/device.h>
-#include <linux/mmzone.h>
-#include <linux/node.h>
-#include <linux/topology.h>
-#include <linux/nodemask.h>
-
-struct i386_node {
-        struct node node;
-};
-extern struct i386_node node_devices[MAX_NUMNODES];
-
-static inline int arch_register_node(int num){
-        int p_node;
-        struct node *parent = NULL;
-
-        if (!node_online(num))
-                return 0;
-        p_node = parent_node(num);
-
-        if (p_node != num)
-                parent = &node_devices[p_node].node;
-
-        return register_node(&node_devices[num].node, num, parent);
-}
-
-#endif /* _ASM_I386_NODE_H_ */
diff --git a/include/linux/node.h b/include/linux/node.h
index 254dc3de650b..1e5347527fa8 100644
--- a/include/linux/node.h
+++ b/include/linux/node.h
@@ -26,8 +26,12 @@ struct node {
         struct sys_device       sysdev;
 };
 
+extern struct node node_devices[];
+
 extern int register_node(struct node *, int, struct node *);
 extern void unregister_node(struct node *node);
+extern int register_one_node(int nid);
+extern void unregister_one_node(int nid);
 
 #define to_node(sys_device) container_of(sys_device, struct node, sysdev)
 
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index f13783e81eb6..ea4038838b0a 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -256,9 +256,19 @@ int add_memory(int nid, u64 start, u64 size)
         if (ret < 0)
                 goto error;
 
-        /* we online node here. we have no error path from here. */
+        /* we online node here. we can't roll back from here. */
         node_set_online(nid);
 
+        if (new_pgdat) {
+                ret = register_one_node(nid);
+                /*
+                 * If sysfs file of new node can't create, cpu on the node
+                 * can't be hot-added. There is no rollback way now.
+                 * So, check by BUG_ON() to catch it reluctantly..
+                 */
+                BUG_ON(ret);
+        }
+
         /* register this memory as resource */
         register_memory_resource(start, size);