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SubjectRe: [RFC PATCH v3 4/13] memory-hotplug : remove /sys/firmware/memmap/X sysfs
At 07/09/2012 06:26 PM, Yasuaki Ishimatsu Wrote:
> 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);

You should call firmware_map_remove_entry() before remove_sysfs_fw_map_entry(),
otherwise it will cause kernel panicked(entry may be freed in remove_sysfs_fw_map_entry()).

Thanks
Wen Congyang

> +
> + 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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