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    Subject[RFC PATCH 4/12] 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: 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 | 71 +++++++++++++++++++++++++++++++++++++++++++
    include/linux/firmware-map.h | 6 +++
    mm/memory_hotplug.c | 6 +++
    3 files changed, 82 insertions(+), 1 deletion(-)

    Index: linux-3.5-rc4/mm/memory_hotplug.c
    ===================================================================
    --- linux-3.5-rc4.orig/mm/memory_hotplug.c 2012-06-26 13:37:30.546288901 +0900
    +++ linux-3.5-rc4/mm/memory_hotplug.c 2012-06-26 13:44:37.069955820 +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, "System RAM");
    + unlock_memory_hotplug();
    + return 0;

    }
    EXPORT_SYMBOL_GPL(remove_memory);
    Index: linux-3.5-rc4/include/linux/firmware-map.h
    ===================================================================
    --- linux-3.5-rc4.orig/include/linux/firmware-map.h 2012-06-25 04:53:04.000000000 +0900
    +++ linux-3.5-rc4/include/linux/firmware-map.h 2012-06-26 13:44:37.070955807 +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-rc4/drivers/firmware/memmap.c
    ===================================================================
    --- linux-3.5-rc4.orig/drivers/firmware/memmap.c 2012-06-25 04:53:04.000000000 +0900
    +++ linux-3.5-rc4/drivers/firmware/memmap.c 2012-06-26 13:47:17.606948898 +0900
    @@ -123,6 +123,16 @@ 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 +154,31 @@ 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_del(&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 +231,42 @@ int __init firmware_map_add_early(u64 st
    return firmware_map_add_entry(start, end, type, entry);
    }

    +void release_firmware_map_entry(struct firmware_map_entry *entry)
    +{
    + /*
    + * FIXME : There is no idea.
    + * How to free the entry which allocated bootmem?
    + */
    +}
    +
    +/**
    + * 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);
    +
    + release_firmware_map_entry(entry);
    +
    + return 0;
    +}
    +
    /*
    * Sysfs functions -------------------------------------------------------------
    */


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