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Subject[PATCH v5 04/14] memory-hotplug: remove /sys/firmware/memmap/X sysfs
Date
From: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>

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 which is allocated by bootmem.
So the patch makes memory leak. But I think the memory leak size is
very samll. And it does not affect the system.

Signed-off-by: Wen Congyang <wency@cn.fujitsu.com>
Signed-off-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
---
drivers/firmware/memmap.c | 98 +++++++++++++++++++++++++++++++++++++++++-
include/linux/firmware-map.h | 6 +++
mm/memory_hotplug.c | 5 ++-
3 files changed, 106 insertions(+), 3 deletions(-)

diff --git a/drivers/firmware/memmap.c b/drivers/firmware/memmap.c
index 90723e6..49be12a 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 ------------------------------------------------------------------
@@ -41,6 +42,7 @@ struct firmware_map_entry {
const char *type; /* type of the memory range */
struct list_head list; /* entry for the linked list */
struct kobject kobj; /* kobject for each entry */
+ unsigned int bootmem:1; /* allocated from bootmem */
};

/*
@@ -79,7 +81,26 @@ static const struct sysfs_ops memmap_attr_ops = {
.show = memmap_attr_show,
};

+
+static inline struct firmware_map_entry *
+to_memmap_entry(struct kobject *kobj)
+{
+ return container_of(kobj, struct firmware_map_entry, kobj);
+}
+
+static void release_firmware_map_entry(struct kobject *kobj)
+{
+ struct firmware_map_entry *entry = to_memmap_entry(kobj);
+
+ if (entry->bootmem)
+ /* There is no way to free memory allocated from bootmem */
+ return;
+
+ kfree(entry);
+}
+
static struct kobj_type memmap_ktype = {
+ .release = release_firmware_map_entry,
.sysfs_ops = &memmap_attr_ops,
.default_attrs = def_attrs,
};
@@ -94,6 +115,7 @@ static struct kobj_type memmap_ktype = {
* in firmware initialisation code in one single thread of execution.
*/
static LIST_HEAD(map_entries);
+static DEFINE_SPINLOCK(map_entries_lock);

/**
* firmware_map_add_entry() - Does the real work to add a firmware memmap entry.
@@ -118,11 +140,25 @@ 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.
+ **/
+static inline void firmware_map_remove_entry(struct firmware_map_entry *entry)
+{
+ spin_lock(&map_entries_lock);
+ list_del(&entry->list);
+ spin_unlock(&map_entries_lock);
+}
+
/*
* Add memmap entry on sysfs
*/
@@ -144,6 +180,35 @@ 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);
+}
+
+/*
+ * Search memmap entry
+ */
+
+static struct firmware_map_entry * __meminit
+firmware_map_find_entry(u64 start, u64 end, const char *type)
+{
+ struct firmware_map_entry *entry;
+
+ spin_lock(&map_entries_lock);
+ list_for_each_entry(entry, &map_entries, list)
+ if ((entry->start == start) && (entry->end == end) &&
+ (!strcmp(entry->type, type))) {
+ spin_unlock(&map_entries_lock);
+ return entry;
+ }
+
+ spin_unlock(&map_entries_lock);
+ return NULL;
+}
+
/**
* firmware_map_add_hotplug() - Adds a firmware mapping entry when we do
* memory hotplug.
@@ -193,9 +258,36 @@ int __init firmware_map_add_early(u64 start, u64 end, const char *type)
if (WARN_ON(!entry))
return -ENOMEM;

+ entry->bootmem = 1;
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;
+
+ entry = firmware_map_find_entry(start, end - 1, type);
+ if (!entry)
+ return -EINVAL;
+
+ firmware_map_remove_entry(entry);
+
+ /* remove the memmap entry */
+ remove_sysfs_fw_map_entry(entry);
+
+ return 0;
+}
+
/*
* Sysfs functions -------------------------------------------------------------
*/
@@ -217,8 +309,10 @@ 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 43fe52f..71d4fa7 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 dbb04d8..1f5b5bb 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -1442,7 +1442,7 @@ 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;
@@ -1484,6 +1484,9 @@ repeat:
return ret;
}

+ /* remove memmap entry */
+ firmware_map_remove(start, start + size, "System RAM");
+
unlock_memory_hotplug();

return 0;
--
1.7.1


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