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

From: KOSAKI Motohiro
Date: Fri Oct 05 2012 - 15:42:05 EST

On Thu, Oct 4, 2012 at 10:26 PM, Yasuaki Ishimatsu
<isimatu.yasuaki@xxxxxxxxxxxxxx> 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@xxxxxxxxxx>
> CC: Jiang Liu <liuj97@xxxxxxxxx>
> CC: Len Brown <len.brown@xxxxxxxxx>
> CC: Christoph Lameter <cl@xxxxxxxxx>
> Cc: Minchan Kim <minchan.kim@xxxxxxxxx>
> CC: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> CC: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx>
> Signed-off-by: Wen Congyang <wency@xxxxxxxxxxxxxx>
> Signed-off-by: Yasuaki Ishimatsu <isimatu.yasuaki@xxxxxxxxxxxxxx>
>
> ---
> 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.
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