3 files changed, 193 insertions, 14 deletions

diff --git a/drivers/firmware/memmap.c b/drivers/firmware/memmap.c
index 90723e65b081..0b5b5f619c75 100644
--- a/drivers/firmware/memmap.c
+++ b/drivers/firmware/memmap.c
@@ -21,6 +21,7 @@
 #include <linux/types.h>
 #include <linux/bootmem.h>
 #include <linux/slab.h>
+#include <linux/mm.h>
 
 /*
  * Data types ------------------------------------------------------------------
@@ -52,6 +53,9 @@ static ssize_t start_show(struct firmware_map_entry *entry, char *buf);
 static ssize_t end_show(struct firmware_map_entry *entry, char *buf);
 static ssize_t type_show(struct firmware_map_entry *entry, char *buf);
 
+static struct firmware_map_entry * __meminit
+firmware_map_find_entry(u64 start, u64 end, const char *type);
+
 /*
  * Static data -----------------------------------------------------------------
  */
@@ -79,7 +83,52 @@ static const struct sysfs_ops memmap_attr_ops = {
         .show = memmap_attr_show,
 };
 
-static struct kobj_type memmap_ktype = {
+/* Firmware memory map entries. */
+static LIST_HEAD(map_entries);
+static DEFINE_SPINLOCK(map_entries_lock);
+
+/*
+ * For memory hotplug, there is no way to free memory map entries allocated
+ * by boot mem after the system is up. So when we hot-remove memory whose
+ * map entry is allocated by bootmem, we need to remember the storage and
+ * reuse it when the memory is hot-added again.
+ */
+static LIST_HEAD(map_entries_bootmem);
+static DEFINE_SPINLOCK(map_entries_bootmem_lock);
+
+
+static inline struct firmware_map_entry *
+to_memmap_entry(struct kobject *kobj)
+{
+        return container_of(kobj, struct firmware_map_entry, kobj);
+}
+
+static void __meminit release_firmware_map_entry(struct kobject *kobj)
+{
+        struct firmware_map_entry *entry = to_memmap_entry(kobj);
+
+        if (PageReserved(virt_to_page(entry))) {
+                /*
+                 * Remember the storage allocated by bootmem, and reuse it when
+                 * the memory is hot-added again. The entry will be added to
+                 * map_entries_bootmem here, and deleted from &map_entries in
+                 * firmware_map_remove_entry().
+                 */
+                if (firmware_map_find_entry(entry->start, entry->end,
+                    entry->type)) {
+                        spin_lock(&map_entries_bootmem_lock);
+                        list_add(&entry->list, &map_entries_bootmem);
+                        spin_unlock(&map_entries_bootmem_lock);
+                }
+
+                return;
+        }
+
+        kfree(entry);
+}
+
+static struct kobj_type __refdata memmap_ktype = {
+        .release        = release_firmware_map_entry,
         .sysfs_ops      = &memmap_attr_ops,
         .default_attrs  = def_attrs,
 };
@@ -88,13 +137,6 @@ static struct kobj_type memmap_ktype = {
  * Registration functions ------------------------------------------------------
  */
 
-/*
- * Firmware memory map entries. No locking is needed because the
- * firmware_map_add() and firmware_map_add_early() functions are called
- * in firmware initialisation code in one single thread of execution.
- */
-static LIST_HEAD(map_entries);
-
 /**
  * firmware_map_add_entry() - Does the real work to add a firmware memmap entry.
  * @start: Start of the memory range.
@@ -118,11 +160,25 @@ static int firmware_map_add_entry(u64 start, u64 end,
         INIT_LIST_HEAD(&entry->list);
         kobject_init(&entry->kobj, &memmap_ktype);
 
+        spin_lock(&map_entries_lock);
         list_add_tail(&entry->list, &map_entries);
+        spin_unlock(&map_entries_lock);
 
         return 0;
 }
 
+/**
+ * firmware_map_remove_entry() - Does the real work to remove a firmware
+ * memmap entry.
+ * @entry: removed entry.
+ *
+ * The caller must hold map_entries_lock, and release it properly.
+ **/
+static inline void firmware_map_remove_entry(struct firmware_map_entry *entry)
+{
+        list_del(&entry->list);
+}
+
 /*
  * Add memmap entry on sysfs
  */
@@ -144,6 +200,78 @@ static int add_sysfs_fw_map_entry(struct firmware_map_entry *entry)
         return 0;
 }
 
+/*
+ * Remove memmap entry on sysfs
+ */
+static inline void remove_sysfs_fw_map_entry(struct firmware_map_entry *entry)
+{
+        kobject_put(&entry->kobj);
+}
+
+/*
+ * firmware_map_find_entry_in_list() - Search memmap entry in a given list.
+ * @start: Start of the memory range.
+ * @end:   End of the memory range (exclusive).
+ * @type:  Type of the memory range.
+ * @list:  In which to find the entry.
+ *
+ * This function is to find the memmap entey of a given memory range in a
+ * given list. The caller must hold map_entries_lock, and must not release
+ * the lock until the processing of the returned entry has completed.
+ *
+ * Return: Pointer to the entry to be found on success, or NULL on failure.
+ */
+static struct firmware_map_entry * __meminit
+firmware_map_find_entry_in_list(u64 start, u64 end, const char *type,
+                                struct list_head *list)
+{
+        struct firmware_map_entry *entry;
+
+        list_for_each_entry(entry, list, list)
+                if ((entry->start == start) && (entry->end == end) &&
+                    (!strcmp(entry->type, type))) {
+                        return entry;
+                }
+
+        return NULL;
+}
+
+/*
+ * firmware_map_find_entry() - Search memmap entry in map_entries.
+ * @start: Start of the memory range.
+ * @end:   End of the memory range (exclusive).
+ * @type:  Type of the memory range.
+ *
+ * This function is to find the memmap entey of a given memory range.
+ * The caller must hold map_entries_lock, and must not release the lock
+ * until the processing of the returned entry has completed.
+ *
+ * Return: Pointer to the entry to be found on success, or NULL on failure.
+ */
+static struct firmware_map_entry * __meminit
+firmware_map_find_entry(u64 start, u64 end, const char *type)
+{
+        return firmware_map_find_entry_in_list(start, end, type, &map_entries);
+}
+
+/*
+ * firmware_map_find_entry_bootmem() - Search memmap entry in map_entries_bootmem.
+ * @start: Start of the memory range.
+ * @end:   End of the memory range (exclusive).
+ * @type:  Type of the memory range.
+ *
+ * This function is similar to firmware_map_find_entry except that it find the
+ * given entry in map_entries_bootmem.
+ *
+ * Return: Pointer to the entry to be found on success, or NULL on failure.
+ */
+static struct firmware_map_entry * __meminit
+firmware_map_find_entry_bootmem(u64 start, u64 end, const char *type)
+{
+        return firmware_map_find_entry_in_list(start, end, type,
+                                               &map_entries_bootmem);
+}
+
 /**
  * firmware_map_add_hotplug() - Adds a firmware mapping entry when we do
  * memory hotplug.
@@ -161,9 +289,19 @@ int __meminit firmware_map_add_hotplug(u64 start, u64 end, const char *type)
 {
         struct firmware_map_entry *entry;
 
-        entry = kzalloc(sizeof(struct firmware_map_entry), GFP_ATOMIC);
-        if (!entry)
-                return -ENOMEM;
+        entry = firmware_map_find_entry_bootmem(start, end, type);
+        if (!entry) {
+                entry = kzalloc(sizeof(struct firmware_map_entry), GFP_ATOMIC);
+                if (!entry)
+                        return -ENOMEM;
+        } else {
+                /* Reuse storage allocated by bootmem. */
+                spin_lock(&map_entries_bootmem_lock);
+                list_del(&entry->list);
+                spin_unlock(&map_entries_bootmem_lock);
+
+                memset(entry, 0, sizeof(*entry));
+        }
 
         firmware_map_add_entry(start, end, type, entry);
         /* create the memmap entry */
@@ -196,6 +334,36 @@ int __init firmware_map_add_early(u64 start, u64 end, const char *type)
         return firmware_map_add_entry(start, end, type, entry);
 }
 
+/**
+ * firmware_map_remove() - remove a firmware mapping entry
+ * @start: Start of the memory range.
+ * @end:   End of the memory range.
+ * @type:  Type of the memory range.
+ *
+ * removes a firmware mapping entry.
+ *
+ * Returns 0 on success, or -EINVAL if no entry.
+ **/
+int __meminit firmware_map_remove(u64 start, u64 end, const char *type)
+{
+        struct firmware_map_entry *entry;
+
+        spin_lock(&map_entries_lock);
+        entry = firmware_map_find_entry(start, end - 1, type);
+        if (!entry) {
+                spin_unlock(&map_entries_lock);
+                return -EINVAL;
+        }
+
+        firmware_map_remove_entry(entry);
+        spin_unlock(&map_entries_lock);
+
+        /* remove the memmap entry */
+        remove_sysfs_fw_map_entry(entry);
+
+        return 0;
+}
+
 /*
  * Sysfs functions -------------------------------------------------------------
  */
@@ -217,8 +385,10 @@ static ssize_t type_show(struct firmware_map_entry *entry, char *buf)
         return snprintf(buf, PAGE_SIZE, "%s\n", entry->type);
 }
 
-#define to_memmap_attr(_attr) container_of(_attr, struct memmap_attribute, attr)
-#define to_memmap_entry(obj) container_of(obj, struct firmware_map_entry, kobj)
+static inline struct memmap_attribute *to_memmap_attr(struct attribute *attr)
+{
+        return container_of(attr, struct memmap_attribute, attr);
+}
 
 static ssize_t memmap_attr_show(struct kobject *kobj,
                                 struct attribute *attr, char *buf)
diff --git a/include/linux/firmware-map.h b/include/linux/firmware-map.h
index 43fe52fcef0f..71d4fa721db9 100644
--- a/include/linux/firmware-map.h
+++ b/include/linux/firmware-map.h
@@ -25,6 +25,7 @@
 
 int firmware_map_add_early(u64 start, u64 end, const char *type);
 int firmware_map_add_hotplug(u64 start, u64 end, const char *type);
+int firmware_map_remove(u64 start, u64 end, const char *type);
 
 #else /* CONFIG_FIRMWARE_MEMMAP */
 
@@ -38,6 +39,11 @@ static inline int firmware_map_add_hotplug(u64 start, u64 end, const char *type)
         return 0;
 }
 
+static inline int firmware_map_remove(u64 start, u64 end, const char *type)
+{
+        return 0;
+}
+
 #endif /* CONFIG_FIRMWARE_MEMMAP */
 
 #endif /* _LINUX_FIRMWARE_MAP_H */
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index e5b91b12cec3..a776dbf3fa00 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -1460,7 +1460,7 @@ static int is_memblock_offlined_cb(struct memory_block *mem, void *arg)
         return ret;
 }
 
-int remove_memory(u64 start, u64 size)
+int __ref remove_memory(u64 start, u64 size)
 {
         unsigned long start_pfn, end_pfn;
         int ret = 0;
@@ -1510,6 +1510,9 @@ repeat:
                 return ret;
         }
 
+        /* remove memmap entry */
+        firmware_map_remove(start, start + size, "System RAM");
+
         unlock_memory_hotplug();
 
         return 0;