/*
   * Slab allocator functions that are independent of the allocator strategy
   *
   * (C) 2012 Christoph Lameter <cl@linux.com>
   */
  #include <linux/slab.h>
  
  #include <linux/mm.h>
  #include <linux/poison.h>
  #include <linux/interrupt.h>
  #include <linux/memory.h>
  #include <linux/compiler.h>
  #include <linux/module.h>

  #include <linux/cpu.h>
  #include <linux/uaccess.h>

  #include <linux/seq_file.h>
  #include <linux/proc_fs.h>

  #include <asm/cacheflush.h>
  #include <asm/tlbflush.h>
  #include <asm/page.h>

  #include <linux/memcontrol.h>

  #include <trace/events/kmem.h>

  #include "slab.h"
  
  enum slab_state slab_state;

  LIST_HEAD(slab_caches);
  DEFINE_MUTEX(slab_mutex);

  struct kmem_cache *kmem_cache;

  #ifdef CONFIG_DEBUG_VM

  static int kmem_cache_sanity_check(const char *name, size_t size)

  {
  	struct kmem_cache *s = NULL;

  	if (!name || in_interrupt() || size < sizeof(void *) ||
  		size > KMALLOC_MAX_SIZE) {

  		pr_err("kmem_cache_create(%s) integrity check failed
  ", name);
  		return -EINVAL;

  	}

  	list_for_each_entry(s, &slab_caches, list) {
  		char tmp;
  		int res;
  
  		/*
  		 * This happens when the module gets unloaded and doesn't
  		 * destroy its slab cache and no-one else reuses the vmalloc
  		 * area of the module.  Print a warning.
  		 */
  		res = probe_kernel_address(s->name, tmp);
  		if (res) {

  			pr_err("Slab cache with size %d has lost its name
  ",

  			       s->object_size);
  			continue;
  		}

  #if !defined(CONFIG_SLUB) || !defined(CONFIG_SLUB_DEBUG_ON)

  		if (!strcmp(s->name, name)) {

  			pr_err("%s (%s): Cache name already exists.
  ",
  			       __func__, name);

  			dump_stack();
  			s = NULL;

  			return -EINVAL;

  		}

  #endif

  	}
  
  	WARN_ON(strchr(name, ' '));	/* It confuses parsers */

  	return 0;
  }
  #else

  static inline int kmem_cache_sanity_check(const char *name, size_t size)

  {
  	return 0;
  }

  #endif

  #ifdef CONFIG_MEMCG_KMEM
  int memcg_update_all_caches(int num_memcgs)
  {
  	struct kmem_cache *s;
  	int ret = 0;
  	mutex_lock(&slab_mutex);
  
  	list_for_each_entry(s, &slab_caches, list) {
  		if (!is_root_cache(s))
  			continue;
  
  		ret = memcg_update_cache_size(s, num_memcgs);
  		/*
  		 * See comment in memcontrol.c, memcg_update_cache_size:
  		 * Instead of freeing the memory, we'll just leave the caches
  		 * up to this point in an updated state.
  		 */
  		if (ret)
  			goto out;
  	}
  
  	memcg_update_array_size(num_memcgs);
  out:
  	mutex_unlock(&slab_mutex);
  	return ret;
  }
  #endif

  /*

   * Figure out what the alignment of the objects will be given a set of
   * flags, a user specified alignment and the size of the objects.
   */
  unsigned long calculate_alignment(unsigned long flags,
  		unsigned long align, unsigned long size)
  {
  	/*
  	 * If the user wants hardware cache aligned objects then follow that
  	 * suggestion if the object is sufficiently large.
  	 *
  	 * The hardware cache alignment cannot override the specified
  	 * alignment though. If that is greater then use it.
  	 */
  	if (flags & SLAB_HWCACHE_ALIGN) {
  		unsigned long ralign = cache_line_size();
  		while (size <= ralign / 2)
  			ralign /= 2;
  		align = max(align, ralign);
  	}
  
  	if (align < ARCH_SLAB_MINALIGN)
  		align = ARCH_SLAB_MINALIGN;
  
  	return ALIGN(align, sizeof(void *));
  }

  static struct kmem_cache *
  do_kmem_cache_create(char *name, size_t object_size, size_t size, size_t align,
  		     unsigned long flags, void (*ctor)(void *),
  		     struct mem_cgroup *memcg, struct kmem_cache *root_cache)
  {
  	struct kmem_cache *s;
  	int err;
  
  	err = -ENOMEM;
  	s = kmem_cache_zalloc(kmem_cache, GFP_KERNEL);
  	if (!s)
  		goto out;
  
  	s->name = name;
  	s->object_size = object_size;
  	s->size = size;
  	s->align = align;
  	s->ctor = ctor;
  
  	err = memcg_alloc_cache_params(memcg, s, root_cache);
  	if (err)
  		goto out_free_cache;
  
  	err = __kmem_cache_create(s, flags);
  	if (err)
  		goto out_free_cache;
  
  	s->refcount = 1;
  	list_add(&s->list, &slab_caches);
  	memcg_register_cache(s);
  out:
  	if (err)
  		return ERR_PTR(err);
  	return s;
  
  out_free_cache:
  	memcg_free_cache_params(s);
  	kfree(s);
  	goto out;
  }

  
  /*

   * kmem_cache_create - Create a cache.
   * @name: A string which is used in /proc/slabinfo to identify this cache.
   * @size: The size of objects to be created in this cache.
   * @align: The required alignment for the objects.
   * @flags: SLAB flags
   * @ctor: A constructor for the objects.
   *
   * Returns a ptr to the cache on success, NULL on failure.
   * Cannot be called within a interrupt, but can be interrupted.
   * The @ctor is run when new pages are allocated by the cache.
   *
   * The flags are
   *
   * %SLAB_POISON - Poison the slab with a known test pattern (a5a5a5a5)
   * to catch references to uninitialised memory.
   *
   * %SLAB_RED_ZONE - Insert `Red' zones around the allocated memory to check
   * for buffer overruns.
   *
   * %SLAB_HWCACHE_ALIGN - Align the objects in this cache to a hardware
   * cacheline.  This can be beneficial if you're counting cycles as closely
   * as davem.
   */

  struct kmem_cache *

  kmem_cache_create(const char *name, size_t size, size_t align,
  		  unsigned long flags, void (*ctor)(void *))

  {

  	struct kmem_cache *s;
  	char *cache_name;

  	int err;

  	get_online_cpus();
  	mutex_lock(&slab_mutex);

  	err = kmem_cache_sanity_check(name, size);

  	if (err)
  		goto out_unlock;

  	/*
  	 * Some allocators will constraint the set of valid flags to a subset
  	 * of all flags. We expect them to define CACHE_CREATE_MASK in this
  	 * case, and we'll just provide them with a sanitized version of the
  	 * passed flags.
  	 */
  	flags &= CACHE_CREATE_MASK;

  	s = __kmem_cache_alias(name, size, align, flags, ctor);
  	if (s)

  		goto out_unlock;

  	cache_name = kstrdup(name, GFP_KERNEL);
  	if (!cache_name) {
  		err = -ENOMEM;
  		goto out_unlock;
  	}

  	s = do_kmem_cache_create(cache_name, size, size,
  				 calculate_alignment(flags, align, size),
  				 flags, ctor, NULL, NULL);
  	if (IS_ERR(s)) {
  		err = PTR_ERR(s);
  		kfree(cache_name);
  	}

  
  out_unlock:

  	mutex_unlock(&slab_mutex);
  	put_online_cpus();

  	if (err) {

  		if (flags & SLAB_PANIC)
  			panic("kmem_cache_create: Failed to create slab '%s'. Error %d
  ",
  				name, err);
  		else {
  			printk(KERN_WARNING "kmem_cache_create(%s) failed with error %d",
  				name, err);
  			dump_stack();
  		}

  		return NULL;
  	}

  	return s;
  }

  EXPORT_SYMBOL(kmem_cache_create);

  #ifdef CONFIG_MEMCG_KMEM
  /*
   * kmem_cache_create_memcg - Create a cache for a memory cgroup.
   * @memcg: The memory cgroup the new cache is for.
   * @root_cache: The parent of the new cache.
   *
   * This function attempts to create a kmem cache that will serve allocation
   * requests going from @memcg to @root_cache. The new cache inherits properties
   * from its parent.
   */
  void kmem_cache_create_memcg(struct mem_cgroup *memcg, struct kmem_cache *root_cache)

  {

  	struct kmem_cache *s;
  	char *cache_name;
  
  	get_online_cpus();
  	mutex_lock(&slab_mutex);
  
  	/*
  	 * Since per-memcg caches are created asynchronously on first
  	 * allocation (see memcg_kmem_get_cache()), several threads can try to
  	 * create the same cache, but only one of them may succeed.
  	 */
  	if (cache_from_memcg_idx(root_cache, memcg_cache_id(memcg)))
  		goto out_unlock;
  
  	cache_name = memcg_create_cache_name(memcg, root_cache);
  	if (!cache_name)
  		goto out_unlock;
  
  	s = do_kmem_cache_create(cache_name, root_cache->object_size,
  				 root_cache->size, root_cache->align,
  				 root_cache->flags, root_cache->ctor,
  				 memcg, root_cache);
  	if (IS_ERR(s)) {
  		kfree(cache_name);
  		goto out_unlock;
  	}
  
  	s->allocflags |= __GFP_KMEMCG;
  
  out_unlock:
  	mutex_unlock(&slab_mutex);
  	put_online_cpus();

  }

  
  static int kmem_cache_destroy_memcg_children(struct kmem_cache *s)
  {
  	int rc;
  
  	if (!s->memcg_params ||
  	    !s->memcg_params->is_root_cache)
  		return 0;
  
  	mutex_unlock(&slab_mutex);
  	rc = __kmem_cache_destroy_memcg_children(s);
  	mutex_lock(&slab_mutex);
  
  	return rc;
  }
  #else
  static int kmem_cache_destroy_memcg_children(struct kmem_cache *s)
  {
  	return 0;
  }

  #endif /* CONFIG_MEMCG_KMEM */

  void kmem_cache_destroy(struct kmem_cache *s)
  {
  	get_online_cpus();
  	mutex_lock(&slab_mutex);

  	s->refcount--;

  	if (s->refcount)
  		goto out_unlock;
  
  	if (kmem_cache_destroy_memcg_children(s) != 0)
  		goto out_unlock;
  
  	list_del(&s->list);
  	memcg_unregister_cache(s);
  
  	if (__kmem_cache_shutdown(s) != 0) {
  		list_add(&s->list, &slab_caches);
  		memcg_register_cache(s);
  		printk(KERN_ERR "kmem_cache_destroy %s: "
  		       "Slab cache still has objects
  ", s->name);
  		dump_stack();
  		goto out_unlock;

  	}

  
  	mutex_unlock(&slab_mutex);
  	if (s->flags & SLAB_DESTROY_BY_RCU)
  		rcu_barrier();
  
  	memcg_free_cache_params(s);
  	kfree(s->name);
  	kmem_cache_free(kmem_cache, s);
  	goto out_put_cpus;
  
  out_unlock:
  	mutex_unlock(&slab_mutex);
  out_put_cpus:

  	put_online_cpus();
  }
  EXPORT_SYMBOL(kmem_cache_destroy);

  int slab_is_available(void)
  {
  	return slab_state >= UP;
  }

  #ifndef CONFIG_SLOB
  /* Create a cache during boot when no slab services are available yet */
  void __init create_boot_cache(struct kmem_cache *s, const char *name, size_t size,
  		unsigned long flags)
  {
  	int err;
  
  	s->name = name;
  	s->size = s->object_size = size;

  	s->align = calculate_alignment(flags, ARCH_KMALLOC_MINALIGN, size);

  	err = __kmem_cache_create(s, flags);
  
  	if (err)

  		panic("Creation of kmalloc slab %s size=%zu failed. Reason %d
  ",

  					name, size, err);
  
  	s->refcount = -1;	/* Exempt from merging for now */
  }
  
  struct kmem_cache *__init create_kmalloc_cache(const char *name, size_t size,
  				unsigned long flags)
  {
  	struct kmem_cache *s = kmem_cache_zalloc(kmem_cache, GFP_NOWAIT);
  
  	if (!s)
  		panic("Out of memory when creating slab %s
  ", name);
  
  	create_boot_cache(s, name, size, flags);
  	list_add(&s->list, &slab_caches);
  	s->refcount = 1;
  	return s;
  }

  struct kmem_cache *kmalloc_caches[KMALLOC_SHIFT_HIGH + 1];
  EXPORT_SYMBOL(kmalloc_caches);
  
  #ifdef CONFIG_ZONE_DMA
  struct kmem_cache *kmalloc_dma_caches[KMALLOC_SHIFT_HIGH + 1];
  EXPORT_SYMBOL(kmalloc_dma_caches);
  #endif

  /*

   * Conversion table for small slabs sizes / 8 to the index in the
   * kmalloc array. This is necessary for slabs < 192 since we have non power
   * of two cache sizes there. The size of larger slabs can be determined using
   * fls.
   */
  static s8 size_index[24] = {
  	3,	/* 8 */
  	4,	/* 16 */
  	5,	/* 24 */
  	5,	/* 32 */
  	6,	/* 40 */
  	6,	/* 48 */
  	6,	/* 56 */
  	6,	/* 64 */
  	1,	/* 72 */
  	1,	/* 80 */
  	1,	/* 88 */
  	1,	/* 96 */
  	7,	/* 104 */
  	7,	/* 112 */
  	7,	/* 120 */
  	7,	/* 128 */
  	2,	/* 136 */
  	2,	/* 144 */
  	2,	/* 152 */
  	2,	/* 160 */
  	2,	/* 168 */
  	2,	/* 176 */
  	2,	/* 184 */
  	2	/* 192 */
  };
  
  static inline int size_index_elem(size_t bytes)
  {
  	return (bytes - 1) / 8;
  }
  
  /*
   * Find the kmem_cache structure that serves a given size of
   * allocation
   */
  struct kmem_cache *kmalloc_slab(size_t size, gfp_t flags)
  {
  	int index;

  	if (unlikely(size > KMALLOC_MAX_SIZE)) {

  		WARN_ON_ONCE(!(flags & __GFP_NOWARN));

  		return NULL;

  	}

  	if (size <= 192) {
  		if (!size)
  			return ZERO_SIZE_PTR;
  
  		index = size_index[size_index_elem(size)];
  	} else
  		index = fls(size - 1);
  
  #ifdef CONFIG_ZONE_DMA

  	if (unlikely((flags & GFP_DMA)))

  		return kmalloc_dma_caches[index];
  
  #endif
  	return kmalloc_caches[index];
  }
  
  /*

   * Create the kmalloc array. Some of the regular kmalloc arrays
   * may already have been created because they were needed to
   * enable allocations for slab creation.
   */
  void __init create_kmalloc_caches(unsigned long flags)
  {
  	int i;

  	/*
  	 * Patch up the size_index table if we have strange large alignment
  	 * requirements for the kmalloc array. This is only the case for
  	 * MIPS it seems. The standard arches will not generate any code here.
  	 *
  	 * Largest permitted alignment is 256 bytes due to the way we
  	 * handle the index determination for the smaller caches.
  	 *
  	 * Make sure that nothing crazy happens if someone starts tinkering
  	 * around with ARCH_KMALLOC_MINALIGN
  	 */
  	BUILD_BUG_ON(KMALLOC_MIN_SIZE > 256 ||
  		(KMALLOC_MIN_SIZE & (KMALLOC_MIN_SIZE - 1)));
  
  	for (i = 8; i < KMALLOC_MIN_SIZE; i += 8) {
  		int elem = size_index_elem(i);
  
  		if (elem >= ARRAY_SIZE(size_index))
  			break;
  		size_index[elem] = KMALLOC_SHIFT_LOW;
  	}
  
  	if (KMALLOC_MIN_SIZE >= 64) {
  		/*
  		 * The 96 byte size cache is not used if the alignment
  		 * is 64 byte.
  		 */
  		for (i = 64 + 8; i <= 96; i += 8)
  			size_index[size_index_elem(i)] = 7;
  
  	}
  
  	if (KMALLOC_MIN_SIZE >= 128) {
  		/*
  		 * The 192 byte sized cache is not used if the alignment
  		 * is 128 byte. Redirect kmalloc to use the 256 byte cache
  		 * instead.
  		 */
  		for (i = 128 + 8; i <= 192; i += 8)
  			size_index[size_index_elem(i)] = 8;
  	}

  	for (i = KMALLOC_SHIFT_LOW; i <= KMALLOC_SHIFT_HIGH; i++) {
  		if (!kmalloc_caches[i]) {

  			kmalloc_caches[i] = create_kmalloc_cache(NULL,
  							1 << i, flags);

  		}

  		/*
  		 * Caches that are not of the two-to-the-power-of size.
  		 * These have to be created immediately after the
  		 * earlier power of two caches
  		 */
  		if (KMALLOC_MIN_SIZE <= 32 && !kmalloc_caches[1] && i == 6)
  			kmalloc_caches[1] = create_kmalloc_cache(NULL, 96, flags);

  		if (KMALLOC_MIN_SIZE <= 64 && !kmalloc_caches[2] && i == 7)
  			kmalloc_caches[2] = create_kmalloc_cache(NULL, 192, flags);

  	}

  	/* Kmalloc array is now usable */
  	slab_state = UP;
  
  	for (i = 0; i <= KMALLOC_SHIFT_HIGH; i++) {
  		struct kmem_cache *s = kmalloc_caches[i];
  		char *n;
  
  		if (s) {
  			n = kasprintf(GFP_NOWAIT, "kmalloc-%d", kmalloc_size(i));
  
  			BUG_ON(!n);
  			s->name = n;
  		}
  	}
  
  #ifdef CONFIG_ZONE_DMA
  	for (i = 0; i <= KMALLOC_SHIFT_HIGH; i++) {
  		struct kmem_cache *s = kmalloc_caches[i];
  
  		if (s) {
  			int size = kmalloc_size(i);
  			char *n = kasprintf(GFP_NOWAIT,
  				 "dma-kmalloc-%d", size);
  
  			BUG_ON(!n);
  			kmalloc_dma_caches[i] = create_kmalloc_cache(n,
  				size, SLAB_CACHE_DMA | flags);
  		}
  	}
  #endif
  }

  #endif /* !CONFIG_SLOB */

  #ifdef CONFIG_TRACING
  void *kmalloc_order_trace(size_t size, gfp_t flags, unsigned int order)
  {
  	void *ret = kmalloc_order(size, flags, order);
  	trace_kmalloc(_RET_IP_, ret, size, PAGE_SIZE << order, flags);
  	return ret;
  }
  EXPORT_SYMBOL(kmalloc_order_trace);
  #endif

  #ifdef CONFIG_SLABINFO

  
  #ifdef CONFIG_SLAB
  #define SLABINFO_RIGHTS (S_IWUSR | S_IRUSR)
  #else
  #define SLABINFO_RIGHTS S_IRUSR
  #endif

  void print_slabinfo_header(struct seq_file *m)

  {
  	/*
  	 * Output format version, so at least we can change it
  	 * without _too_ many complaints.
  	 */
  #ifdef CONFIG_DEBUG_SLAB
  	seq_puts(m, "slabinfo - version: 2.1 (statistics)
  ");
  #else
  	seq_puts(m, "slabinfo - version: 2.1
  ");
  #endif
  	seq_puts(m, "# name            <active_objs> <num_objs> <objsize> "
  		 "<objperslab> <pagesperslab>");
  	seq_puts(m, " : tunables <limit> <batchcount> <sharedfactor>");
  	seq_puts(m, " : slabdata <active_slabs> <num_slabs> <sharedavail>");
  #ifdef CONFIG_DEBUG_SLAB
  	seq_puts(m, " : globalstat <listallocs> <maxobjs> <grown> <reaped> "
  		 "<error> <maxfreeable> <nodeallocs> <remotefrees> <alienoverflow>");
  	seq_puts(m, " : cpustat <allochit> <allocmiss> <freehit> <freemiss>");
  #endif
  	seq_putc(m, '
  ');
  }

  static void *s_start(struct seq_file *m, loff_t *pos)
  {
  	loff_t n = *pos;
  
  	mutex_lock(&slab_mutex);
  	if (!n)
  		print_slabinfo_header(m);
  
  	return seq_list_start(&slab_caches, *pos);
  }

  void *slab_next(struct seq_file *m, void *p, loff_t *pos)

  {
  	return seq_list_next(p, &slab_caches, pos);
  }

  void slab_stop(struct seq_file *m, void *p)

  {
  	mutex_unlock(&slab_mutex);
  }

  static void
  memcg_accumulate_slabinfo(struct kmem_cache *s, struct slabinfo *info)
  {
  	struct kmem_cache *c;
  	struct slabinfo sinfo;
  	int i;
  
  	if (!is_root_cache(s))
  		return;
  
  	for_each_memcg_cache_index(i) {

  		c = cache_from_memcg_idx(s, i);

  		if (!c)
  			continue;
  
  		memset(&sinfo, 0, sizeof(sinfo));
  		get_slabinfo(c, &sinfo);
  
  		info->active_slabs += sinfo.active_slabs;
  		info->num_slabs += sinfo.num_slabs;
  		info->shared_avail += sinfo.shared_avail;
  		info->active_objs += sinfo.active_objs;
  		info->num_objs += sinfo.num_objs;
  	}
  }
  
  int cache_show(struct kmem_cache *s, struct seq_file *m)

  {

  	struct slabinfo sinfo;
  
  	memset(&sinfo, 0, sizeof(sinfo));
  	get_slabinfo(s, &sinfo);

  	memcg_accumulate_slabinfo(s, &sinfo);

  	seq_printf(m, "%-17s %6lu %6lu %6u %4u %4d",

  		   cache_name(s), sinfo.active_objs, sinfo.num_objs, s->size,

  		   sinfo.objects_per_slab, (1 << sinfo.cache_order));
  
  	seq_printf(m, " : tunables %4u %4u %4u",
  		   sinfo.limit, sinfo.batchcount, sinfo.shared);
  	seq_printf(m, " : slabdata %6lu %6lu %6lu",
  		   sinfo.active_slabs, sinfo.num_slabs, sinfo.shared_avail);
  	slabinfo_show_stats(m, s);
  	seq_putc(m, '
  ');
  	return 0;

  }

  static int s_show(struct seq_file *m, void *p)
  {
  	struct kmem_cache *s = list_entry(p, struct kmem_cache, list);
  
  	if (!is_root_cache(s))
  		return 0;
  	return cache_show(s, m);
  }

  /*
   * slabinfo_op - iterator that generates /proc/slabinfo
   *
   * Output layout:
   * cache-name
   * num-active-objs
   * total-objs
   * object size
   * num-active-slabs
   * total-slabs
   * num-pages-per-slab
   * + further values on SMP and with statistics enabled
   */
  static const struct seq_operations slabinfo_op = {
  	.start = s_start,

  	.next = slab_next,
  	.stop = slab_stop,

  	.show = s_show,
  };
  
  static int slabinfo_open(struct inode *inode, struct file *file)
  {
  	return seq_open(file, &slabinfo_op);
  }
  
  static const struct file_operations proc_slabinfo_operations = {
  	.open		= slabinfo_open,
  	.read		= seq_read,
  	.write          = slabinfo_write,
  	.llseek		= seq_lseek,
  	.release	= seq_release,
  };
  
  static int __init slab_proc_init(void)
  {

  	proc_create("slabinfo", SLABINFO_RIGHTS, NULL,
  						&proc_slabinfo_operations);

  	return 0;
  }
  module_init(slab_proc_init);
  #endif /* CONFIG_SLABINFO */