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    Subject[RFC V7 PATCH 08/19] 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 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 | 9 ++++-
    3 files changed, 90 insertions(+), 3 deletions(-)
    diff --git a/drivers/firmware/memmap.c b/drivers/firmware/memmap.c
    index c1cdc92..b2e7e5e 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 ------------------------------------------------------------------
    @@ -79,7 +80,22 @@ static const struct sysfs_ops memmap_attr_ops = {
    .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 *page;
    +
    + page = virt_to_page(entry);
    + if (PageSlab(page) || PageCompound(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 start, u64 end,
    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 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
    + */
    +
    +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 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;
    +
    + entry = find_firmware_map_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 -------------------------------------------------------------
    */
    @@ -218,7 +295,6 @@ static ssize_t type_show(struct firmware_map_entry *entry, char *buf)
    }

    #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)
    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 3f1d7c5..45b03b3 100644
    --- a/mm/memory_hotplug.c
    +++ b/mm/memory_hotplug.c
    @@ -1052,9 +1052,9 @@ int offline_memory(u64 start, u64 size)
    return 0;
    }

    -int remove_memory(int nid, u64 start, u64 size)
    +int __ref remove_memory(int nid, u64 start, u64 size)
    {
    - int ret = -EBUSY;
    + int ret = 0;
    lock_memory_hotplug();
    /*
    * The memory might become online by other task, even if you offine it.
    @@ -1065,8 +1065,13 @@ int remove_memory(int nid, u64 start, u64 size)
    "because the memmory range is online\n",
    start, start + size);
    ret = -EAGAIN;
    + goto out;
    }

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

    --
    1.7.1


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