1 files changed, 57 insertions, 37 deletions

diff --git a/drivers/base/memory.c b/drivers/base/memory.c
index 933442f40321..cafeaaf0428f 100644
--- a/drivers/base/memory.c
+++ b/drivers/base/memory.c
@@ -27,6 +27,8 @@
 #include <asm/atomic.h>
 #include <asm/uaccess.h>
 
+static DEFINE_MUTEX(mem_sysfs_mutex);
+
 #define MEMORY_CLASS_NAME       "memory"
 
 static struct sysdev_class memory_sysdev_class = {
@@ -435,6 +437,45 @@ int __weak arch_get_memory_phys_device(unsigned long start_pfn)
         return 0;
 }
 
+struct memory_block *find_memory_block_hinted(struct mem_section *section,
+                                              struct memory_block *hint)
+{
+        struct kobject *kobj;
+        struct sys_device *sysdev;
+        struct memory_block *mem;
+        char name[sizeof(MEMORY_CLASS_NAME) + 9 + 1];
+
+        kobj = hint ? &hint->sysdev.kobj : NULL;
+
+        /*
+         * This only works because we know that section == sysdev->id
+         * slightly redundant with sysdev_register()
+         */
+        sprintf(&name[0], "%s%d", MEMORY_CLASS_NAME, __section_nr(section));
+
+        kobj = kset_find_obj_hinted(&memory_sysdev_class.kset, name, kobj);
+        if (!kobj)
+                return NULL;
+
+        sysdev = container_of(kobj, struct sys_device, kobj);
+        mem = container_of(sysdev, struct memory_block, sysdev);
+
+        return mem;
+}
+
+/*
+ * For now, we have a linear search to go find the appropriate
+ * memory_block corresponding to a particular phys_index. If
+ * this gets to be a real problem, we can always use a radix
+ * tree or something here.
+ *
+ * This could be made generic for all sysdev classes.
+ */
+struct memory_block *find_memory_block(struct mem_section *section)
+{
+        return find_memory_block_hinted(section, NULL);
+}
+
 static int add_memory_block(int nid, struct mem_section *section,
                         unsigned long state, enum mem_add_context context)
 {
@@ -445,8 +486,11 @@ static int add_memory_block(int nid, struct mem_section *section,
         if (!mem)
                 return -ENOMEM;
 
+        mutex_lock(&mem_sysfs_mutex);
+
         mem->phys_index = __section_nr(section);
         mem->state = state;
+        mem->section_count++;
         mutex_init(&mem->state_mutex);
         start_pfn = section_nr_to_pfn(mem->phys_index);
         mem->phys_device = arch_get_memory_phys_device(start_pfn);
@@ -465,53 +509,29 @@ static int add_memory_block(int nid, struct mem_section *section,
                         ret = register_mem_sect_under_node(mem, nid);
         }
 
+        mutex_unlock(&mem_sysfs_mutex);
         return ret;
 }
 
-/*
- * For now, we have a linear search to go find the appropriate
- * memory_block corresponding to a particular phys_index. If
- * this gets to be a real problem, we can always use a radix
- * tree or something here.
- *
- * This could be made generic for all sysdev classes.
- */
-struct memory_block *find_memory_block(struct mem_section *section)
-{
-        struct kobject *kobj;
-        struct sys_device *sysdev;
-        struct memory_block *mem;
-        char name[sizeof(MEMORY_CLASS_NAME) + 9 + 1];
-
-        /*
-         * This only works because we know that section == sysdev->id
-         * slightly redundant with sysdev_register()
-         */
-        sprintf(&name[0], "%s%d", MEMORY_CLASS_NAME, __section_nr(section));
-
-        kobj = kset_find_obj(&memory_sysdev_class.kset, name);
-        if (!kobj)
-                return NULL;
-
-        sysdev = container_of(kobj, struct sys_device, kobj);
-        mem = container_of(sysdev, struct memory_block, sysdev);
-
-        return mem;
-}
-
 int remove_memory_block(unsigned long node_id, struct mem_section *section,
                 int phys_device)
 {
         struct memory_block *mem;
 
+        mutex_lock(&mem_sysfs_mutex);
         mem = find_memory_block(section);
-        unregister_mem_sect_under_nodes(mem);
-        mem_remove_simple_file(mem, phys_index);
-        mem_remove_simple_file(mem, state);
-        mem_remove_simple_file(mem, phys_device);
-        mem_remove_simple_file(mem, removable);
-        unregister_memory(mem, section);
 
+        mem->section_count--;
+        if (mem->section_count == 0) {
+                unregister_mem_sect_under_nodes(mem);
+                mem_remove_simple_file(mem, phys_index);
+                mem_remove_simple_file(mem, state);
+                mem_remove_simple_file(mem, phys_device);
+                mem_remove_simple_file(mem, removable);
+                unregister_memory(mem, section);
+        }
+
+        mutex_unlock(&mem_sysfs_mutex);
         return 0;
 }