Re: [PATCH 2/10] memory-hotplug : remove /sys/firmware/memmap/X sysfs

[KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>]

On Thu, Oct 4, 2012 at 10:26 PM, Yasuaki Ishimatsu
<isimatu.yasuaki@jp.fujitsu.com> 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.

You have to explain why this is ok. I guess the unfreed
firmware_map_entry is reused
at next online memory and don't make memory leak, right?



>
> CC: David Rientjes <rientjes@google.com>
> CC: Jiang Liu <liuj97@gmail.com>
> CC: Len Brown <len.brown@intel.com>
> 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>
> 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          |    7 ++-
>  3 files changed, 108 insertions(+), 3 deletions(-)
>
> Index: linux-3.6/drivers/firmware/memmap.c
> ===================================================================
> --- linux-3.6.orig/drivers/firmware/memmap.c    2012-10-04 18:27:05.195500420 +0900
> +++ linux-3.6/drivers/firmware/memmap.c 2012-10-04 18:27:18.901514330 +0900
> @@ -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 */

Use bool.


>  };
>
>  /*
> @@ -79,7 +81,26 @@ static const struct sysfs_ops memmap_att
>         .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 st
>         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)

Don't use inline in *.c file. gcc is wise than you.

> +{
> +       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
>         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 st
>         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)

Remove type argument if this is always passed "System RAM".

> +{
> +       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
>         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)
> Index: linux-3.6/include/linux/firmware-map.h
> ===================================================================
> --- linux-3.6.orig/include/linux/firmware-map.h 2012-10-04 18:27:05.197500422 +0900
> +++ linux-3.6/include/linux/firmware-map.h      2012-10-04 18:27:18.904514333 +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-3.6/mm/memory_hotplug.c
> ===================================================================
> --- linux-3.6.orig/mm/memory_hotplug.c  2012-10-04 18:27:03.000000000 +0900
> +++ linux-3.6/mm/memory_hotplug.c       2012-10-04 18:28:42.851599524 +0900
> @@ -1043,7 +1043,7 @@ 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 = 0;
>         lock_memory_hotplug();
> @@ -1056,8 +1056,13 @@ int remove_memory(int nid, u64 start, u6
>                         "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;
>  }


Other than that, looks ok to me.