On Tue, 28 Aug 2012 18:00:15 +0800 wency@xxxxxxxxxxxxxx wrote: > From: Yasuaki Ishimatsu <isimatu.yasuaki@xxxxxxxxxxxxxx> > > 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. > > .... > > +#define to_memmap_entry(obj) container_of(obj, struct firmware_map_entry, kobj) It would be better to implement this as an inlined C function. That has improved type safety and improved readability. > +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)) That PageCompound() test looks rather odd. Why is this done? > + kfree(entry); > + > + /* There is no way to free memory allocated from bootmem*/ > +} This function is a bit ugly - poking around in page flags to determine whether or not the memory came from bootmem. It would be cleaner to use a separate boolean. Although I guess we can live with it as you have it here. > 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); > +} Is there no locking to protect that 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) A better name would be firmware_map_find_entry(). To retain the (good) convention that symbols exported from here all start with "firmware_map_". > +{ > + 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; > +} Again, the lack of locking looks bad. > ... > > --- 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) Why was __ref added? > { > - int ret = -EBUSY; > + int ret = 0; > lock_memory_hotplug(); > /* > * The memory might become online by other task, even if you offine it. > > ... > -- To unsubscribe from this list: send the line "unsubscribe linux-s390" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html