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Subject[RFC PATCH v3 4/13] memory-hotplug : remove /sys/firmware/memmap/X sysfs
When (hot)adding memory into system, /sys/firmware/memmap/X/{end, start, type}
sysfs files are created. But there is no code to remove these files. The patch
implements the function to remove them.
Note : The code does not free firmware_map_entry since there is no way to free
memory which is allocated by bootmem.

CC: David Rientjes <rientjes@google.com>
CC: Jiang Liu <liuj97@gmail.com>
CC: Len Brown <len.brown@intel.com>
CC: Benjamin Herrenschmidt <benh@kernel.crashing.org>
CC: Paul Mackerras <paulus@samba.org>
CC: Christoph Lameter <cl@linux.com>
Cc: Minchan Kim <minchan.kim@gmail.com>
CC: Andrew Morton <akpm@linux-foundation.org>
CC: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
CC: Wen Congyang <wency@cn.fujitsu.com>
Signed-off-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>

---
drivers/firmware/memmap.c | 78 ++++++++++++++++++++++++++++++++++++++++++-
include/linux/firmware-map.h | 6 +++
mm/memory_hotplug.c | 6 ++-
3 files changed, 88 insertions(+), 2 deletions(-)
Index: linux-3.5-rc6/mm/memory_hotplug.c
===================================================================
--- linux-3.5-rc6.orig/mm/memory_hotplug.c 2012-07-09 18:23:13.323844923 +0900
+++ linux-3.5-rc6/mm/memory_hotplug.c 2012-07-09 18:23:19.522767424 +0900
@@ -661,7 +661,11 @@ EXPORT_SYMBOL_GPL(add_memory);

int remove_memory(int nid, u64 start, u64 size)
{
- return -EBUSY;
+ lock_memory_hotplug();
+ /* remove memmap entry */
+ firmware_map_remove(start, start + size - 1, "System RAM");
+ unlock_memory_hotplug();
+ return 0;

}
EXPORT_SYMBOL_GPL(remove_memory);
Index: linux-3.5-rc6/include/linux/firmware-map.h
===================================================================
--- linux-3.5-rc6.orig/include/linux/firmware-map.h 2012-07-09 18:23:09.532892314 +0900
+++ linux-3.5-rc6/include/linux/firmware-map.h 2012-07-09 18:23:19.523767412 +0900
@@ -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_hotpl
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 */
Index: linux-3.5-rc6/drivers/firmware/memmap.c
===================================================================
--- linux-3.5-rc6.orig/drivers/firmware/memmap.c 2012-07-09 18:23:09.532892314 +0900
+++ linux-3.5-rc6/drivers/firmware/memmap.c 2012-07-09 18:25:46.371931554 +0900
@@ -21,6 +21,7 @@
#include <linux/types.h>
#include <linux/bootmem.h>
#include <linux/slab.h>
+#include <linux/mm.h>

/*
* Data types ------------------------------------------------------------------
@@ -79,7 +80,22 @@ static const struct sysfs_ops memmap_att
.show = memmap_attr_show,
};

+#define to_memmap_entry(obj) container_of(obj, struct firmware_map_entry, kobj)
+
+static void release_firmware_map_entry(struct kobject *kobj)
+{
+ struct firmware_map_entry *entry = to_memmap_entry(kobj);
+ struct page *head_page;
+
+ head_page = virt_to_head_page(entry);
+ if (PageSlab(head_page))
+ kfree(entry);
+
+ /* There is no way to free memory allocated from bootmem*/
+}
+
static struct kobj_type memmap_ktype = {
+ .release = release_firmware_map_entry,
.sysfs_ops = &memmap_attr_ops,
.default_attrs = def_attrs,
};
@@ -123,6 +139,16 @@ static int firmware_map_add_entry(u64 st
return 0;
}

+/**
+ * firmware_map_remove_entry() - Does the real work to remove a firmware
+ * memmap entry.
+ * @entry: removed entry.
+ **/
+static inline void firmware_map_remove_entry(struct firmware_map_entry *entry)
+{
+ list_del(&entry->list);
+}
+
/*
* Add memmap entry on sysfs
*/
@@ -144,6 +170,31 @@ static int add_sysfs_fw_map_entry(struct
return 0;
}

+/*
+ * Remove memmap entry on sysfs
+ */
+static inline void remove_sysfs_fw_map_entry(struct firmware_map_entry *entry)
+{
+ kobject_put(&entry->kobj);
+}
+
+/*
+ * Search memmap entry
+ */
+
+struct firmware_map_entry * __meminit
+find_firmware_map_entry(u64 start, u64 end, const char *type)
+{
+ struct firmware_map_entry *entry;
+
+ list_for_each_entry(entry, &map_entries, list)
+ if ((entry->start == start) && (entry->end == end) &&
+ (!strcmp(entry->type, type)))
+ return entry;
+
+ return NULL;
+}
+
/**
* firmware_map_add_hotplug() - Adds a firmware mapping entry when we do
* memory hotplug.
@@ -196,6 +247,32 @@ int __init firmware_map_add_early(u64 st
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 (inclusive).
+ * @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;
+
+ entry = find_firmware_map_entry(start, end, type);
+ if (!entry)
+ return -EINVAL;
+
+ /* remove the memmap entry */
+ remove_sysfs_fw_map_entry(entry);
+
+ firmware_map_remove_entry(entry);
+
+ return 0;
+}
+
/*
* Sysfs functions -------------------------------------------------------------
*/
@@ -218,7 +295,6 @@ static ssize_t type_show(struct firmware
}

#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 ssize_t memmap_attr_show(struct kobject *kobj,
struct attribute *attr, char *buf)


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