text: /*
   * Written by Mark Hemment, 1996 (markhe@nextd.demon.co.uk).
   *
   * (C) SGI 2006, Christoph Lameter
   * 	Cleaned up and restructured to ease the addition of alternative
   * 	implementations of SLAB allocators.
   */
  
  #ifndef _LINUX_SLAB_H
  #define	_LINUX_SLAB_H
  
  #include <linux/gfp.h>
  #include <linux/types.h>
  #include <linux/workqueue.h>
  
  
  /*
   * Flags to pass to kmem_cache_create().
   * The ones marked DEBUG are only valid if CONFIG_SLAB_DEBUG is set.
   */
  #define SLAB_DEBUG_FREE		0x00000100UL	/* DEBUG: Perform (expensive) checks on free */
  #define SLAB_RED_ZONE		0x00000400UL	/* DEBUG: Red zone objs in a cache */
  #define SLAB_POISON		0x00000800UL	/* DEBUG: Poison objects */
  #define SLAB_HWCACHE_ALIGN	0x00002000UL	/* Align objs on cache lines */
  #define SLAB_CACHE_DMA		0x00004000UL	/* Use GFP_DMA memory */
  #define SLAB_STORE_USER		0x00010000UL	/* DEBUG: Store the last owner for bug hunting */
  #define SLAB_PANIC		0x00040000UL	/* Panic if kmem_cache_create() fails */
  /*
   * SLAB_DESTROY_BY_RCU - **WARNING** READ THIS!
   *
   * This delays freeing the SLAB page by a grace period, it does _NOT_
   * delay object freeing. This means that if you do kmem_cache_free()
   * that memory location is free to be reused at any time. Thus it may
   * be possible to see another object there in the same RCU grace period.
   *
   * This feature only ensures the memory location backing the object
   * stays valid, the trick to using this is relying on an independent
   * object validation pass. Something like:
   *
   *  rcu_read_lock()
   * again:
   *  obj = lockless_lookup(key);
   *  if (obj) {
   *    if (!try_get_ref(obj)) // might fail for free objects
   *      goto again;
   *
   *    if (obj->key != key) { // not the object we expected
   *      put_ref(obj);
   *      goto again;
   *    }
   *  }
   *  rcu_read_unlock();
   *
   * See also the comment on struct slab_rcu in mm/slab.c.
   */
  #define SLAB_DESTROY_BY_RCU	0x00080000UL	/* Defer freeing slabs to RCU */
  #define SLAB_MEM_SPREAD		0x00100000UL	/* Spread some memory over cpuset */
  #define SLAB_TRACE		0x00200000UL	/* Trace allocations and frees */
  
  /* Flag to prevent checks on free */
  #ifdef CONFIG_DEBUG_OBJECTS
  # define SLAB_DEBUG_OBJECTS	0x00400000UL
  #else
  # define SLAB_DEBUG_OBJECTS	0x00000000UL
  #endif
  
  #define SLAB_NOLEAKTRACE	0x00800000UL	/* Avoid kmemleak tracing */
  
  /* Don't track use of uninitialized memory */
  #ifdef CONFIG_KMEMCHECK
  # define SLAB_NOTRACK		0x01000000UL
  #else
  # define SLAB_NOTRACK		0x00000000UL
  #endif
  #ifdef CONFIG_FAILSLAB
  # define SLAB_FAILSLAB		0x02000000UL	/* Fault injection mark */
  #else
  # define SLAB_FAILSLAB		0x00000000UL
  #endif
  
  /* The following flags affect the page allocator grouping pages by mobility */
  #define SLAB_RECLAIM_ACCOUNT	0x00020000UL		/* Objects are reclaimable */
  #define SLAB_TEMPORARY		SLAB_RECLAIM_ACCOUNT	/* Objects are short-lived */
  /*
   * ZERO_SIZE_PTR will be returned for zero sized kmalloc requests.
   *
   * Dereferencing ZERO_SIZE_PTR will lead to a distinct access fault.
   *
   * ZERO_SIZE_PTR can be passed to kfree though in the same way that NULL can.
   * Both make kfree a no-op.
   */
  #define ZERO_SIZE_PTR ((void *)16)
  
  #define ZERO_OR_NULL_PTR(x) ((unsigned long)(x) <= \
  				(unsigned long)ZERO_SIZE_PTR)
  
  
  struct mem_cgroup;
  /*
   * struct kmem_cache related prototypes
   */
  void __init kmem_cache_init(void);
  int slab_is_available(void);
  
  struct kmem_cache *kmem_cache_create(const char *, size_t, size_t,
  			unsigned long,
  			void (*)(void *));
  struct kmem_cache *
  kmem_cache_create_memcg(struct mem_cgroup *, const char *, size_t, size_t,
  			unsigned long, void (*)(void *), struct kmem_cache *);
  void kmem_cache_destroy(struct kmem_cache *);
  int kmem_cache_shrink(struct kmem_cache *);
  void kmem_cache_free(struct kmem_cache *, void *);
  
  /*
   * Please use this macro to create slab caches. Simply specify the
   * name of the structure and maybe some flags that are listed above.
   *
   * The alignment of the struct determines object alignment. If you
   * f.e. add ____cacheline_aligned_in_smp to the struct declaration
   * then the objects will be properly aligned in SMP configurations.
   */
  #define KMEM_CACHE(__struct, __flags) kmem_cache_create(#__struct,\
  		sizeof(struct __struct), __alignof__(struct __struct),\
  		(__flags), NULL)
  
  /*
   * Common kmalloc functions provided by all allocators
   */
  void * __must_check __krealloc(const void *, size_t, gfp_t);
  void * __must_check krealloc(const void *, size_t, gfp_t);
  void kfree(const void *);
  void kzfree(const void *);
  size_t ksize(const void *);
  
  /*
   * Some archs want to perform DMA into kmalloc caches and need a guaranteed
   * alignment larger than the alignment of a 64-bit integer.
   * Setting ARCH_KMALLOC_MINALIGN in arch headers allows that.
   */
  #if defined(ARCH_DMA_MINALIGN) && ARCH_DMA_MINALIGN > 8
  #define ARCH_KMALLOC_MINALIGN ARCH_DMA_MINALIGN
  #define KMALLOC_MIN_SIZE ARCH_DMA_MINALIGN
  #define KMALLOC_SHIFT_LOW ilog2(ARCH_DMA_MINALIGN)
  #else
  #define ARCH_KMALLOC_MINALIGN __alignof__(unsigned long long)
  #endif
  
  #ifdef CONFIG_SLOB
  /*
   * Common fields provided in kmem_cache by all slab allocators
   * This struct is either used directly by the allocator (SLOB)
   * or the allocator must include definitions for all fields
   * provided in kmem_cache_common in their definition of kmem_cache.
   *
   * Once we can do anonymous structs (C11 standard) we could put a
   * anonymous struct definition in these allocators so that the
   * separate allocations in the kmem_cache structure of SLAB and
   * SLUB is no longer needed.
   */
  struct kmem_cache {
  	unsigned int object_size;/* The original size of the object */
  	unsigned int size;	/* The aligned/padded/added on size  */
  	unsigned int align;	/* Alignment as calculated */
  	unsigned long flags;	/* Active flags on the slab */
  	const char *name;	/* Slab name for sysfs */
  	int refcount;		/* Use counter */
  	void (*ctor)(void *);	/* Called on object slot creation */
  	struct list_head list;	/* List of all slab caches on the system */
  };
  
  #define KMALLOC_MAX_SIZE (1UL << 30)
  
  #include <linux/slob_def.h>
  
  #else /* CONFIG_SLOB */
  
  /*
   * Kmalloc array related definitions
   */
  
  #ifdef CONFIG_SLAB
  /*
   * The largest kmalloc size supported by the SLAB allocators is
   * 32 megabyte (2^25) or the maximum allocatable page order if that is
   * less than 32 MB.
   *
   * WARNING: Its not easy to increase this value since the allocators have
   * to do various tricks to work around compiler limitations in order to
   * ensure proper constant folding.
   */
  #define KMALLOC_SHIFT_HIGH	((MAX_ORDER + PAGE_SHIFT - 1) <= 25 ? \
  				(MAX_ORDER + PAGE_SHIFT - 1) : 25)
  #define KMALLOC_SHIFT_MAX	KMALLOC_SHIFT_HIGH
  #ifndef KMALLOC_SHIFT_LOW
  #define KMALLOC_SHIFT_LOW	5
  #endif
  #else
  /*
   * SLUB allocates up to order 2 pages directly and otherwise
   * passes the request to the page allocator.
   */
  #define KMALLOC_SHIFT_HIGH	(PAGE_SHIFT + 1)
  #define KMALLOC_SHIFT_MAX	(MAX_ORDER + PAGE_SHIFT)
  #ifndef KMALLOC_SHIFT_LOW
  #define KMALLOC_SHIFT_LOW	3
  #endif
  #endif
  
  /* Maximum allocatable size */
  #define KMALLOC_MAX_SIZE	(1UL << KMALLOC_SHIFT_MAX)
  /* Maximum size for which we actually use a slab cache */
  #define KMALLOC_MAX_CACHE_SIZE	(1UL << KMALLOC_SHIFT_HIGH)
  /* Maximum order allocatable via the slab allocagtor */
  #define KMALLOC_MAX_ORDER	(KMALLOC_SHIFT_MAX - PAGE_SHIFT)
  
  /*
   * Kmalloc subsystem.
   */
  #ifndef KMALLOC_MIN_SIZE
  #define KMALLOC_MIN_SIZE (1 << KMALLOC_SHIFT_LOW)
  #endif
  
  extern struct kmem_cache *kmalloc_caches[KMALLOC_SHIFT_HIGH + 1];
  #ifdef CONFIG_ZONE_DMA
  extern struct kmem_cache *kmalloc_dma_caches[KMALLOC_SHIFT_HIGH + 1];
  #endif
  
  /*
   * Figure out which kmalloc slab an allocation of a certain size
   * belongs to.
   * 0 = zero alloc
   * 1 =  65 .. 96 bytes
   * 2 = 120 .. 192 bytes
   * n = 2^(n-1) .. 2^n -1
   */
  static __always_inline int kmalloc_index(size_t size)
  {
  	if (!size)
  		return 0;
  
  	if (size <= KMALLOC_MIN_SIZE)
  		return KMALLOC_SHIFT_LOW;
  
  	if (KMALLOC_MIN_SIZE <= 32 && size > 64 && size <= 96)
  		return 1;
  	if (KMALLOC_MIN_SIZE <= 64 && size > 128 && size <= 192)
  		return 2;
  	if (size <=          8) return 3;
  	if (size <=         16) return 4;
  	if (size <=         32) return 5;
  	if (size <=         64) return 6;
  	if (size <=        128) return 7;
  	if (size <=        256) return 8;
  	if (size <=        512) return 9;
  	if (size <=       1024) return 10;
  	if (size <=   2 * 1024) return 11;
  	if (size <=   4 * 1024) return 12;
  	if (size <=   8 * 1024) return 13;
  	if (size <=  16 * 1024) return 14;
  	if (size <=  32 * 1024) return 15;
  	if (size <=  64 * 1024) return 16;
  	if (size <= 128 * 1024) return 17;
  	if (size <= 256 * 1024) return 18;
  	if (size <= 512 * 1024) return 19;
  	if (size <= 1024 * 1024) return 20;
  	if (size <=  2 * 1024 * 1024) return 21;
  	if (size <=  4 * 1024 * 1024) return 22;
  	if (size <=  8 * 1024 * 1024) return 23;
  	if (size <=  16 * 1024 * 1024) return 24;
  	if (size <=  32 * 1024 * 1024) return 25;
  	if (size <=  64 * 1024 * 1024) return 26;
  	BUG();
  
  	/* Will never be reached. Needed because the compiler may complain */
  	return -1;
  }
  
  #ifdef CONFIG_SLAB
  #include <linux/slab_def.h>
  #elif defined(CONFIG_SLUB)
  #include <linux/slub_def.h>
  #else
  #error "Unknown slab allocator"
  #endif
  
  /*
   * Determine size used for the nth kmalloc cache.
   * return size or 0 if a kmalloc cache for that
   * size does not exist
   */
  static __always_inline int kmalloc_size(int n)
  {
  	if (n > 2)
  		return 1 << n;
  
  	if (n == 1 && KMALLOC_MIN_SIZE <= 32)
  		return 96;
  
  	if (n == 2 && KMALLOC_MIN_SIZE <= 64)
  		return 192;
  
  	return 0;
  }
  #endif /* !CONFIG_SLOB */
  
  /*
   * Setting ARCH_SLAB_MINALIGN in arch headers allows a different alignment.
   * Intended for arches that get misalignment faults even for 64 bit integer
   * aligned buffers.
   */
  #ifndef ARCH_SLAB_MINALIGN
  #define ARCH_SLAB_MINALIGN __alignof__(unsigned long long)
  #endif
  /*
   * This is the main placeholder for memcg-related information in kmem caches.
   * struct kmem_cache will hold a pointer to it, so the memory cost while
   * disabled is 1 pointer. The runtime cost while enabled, gets bigger than it
   * would otherwise be if that would be bundled in kmem_cache: we'll need an
   * extra pointer chase. But the trade off clearly lays in favor of not
   * penalizing non-users.
   *
   * Both the root cache and the child caches will have it. For the root cache,
   * this will hold a dynamically allocated array large enough to hold
   * information about the currently limited memcgs in the system.
   *
   * Child caches will hold extra metadata needed for its operation. Fields are:
   *
   * @memcg: pointer to the memcg this cache belongs to
   * @list: list_head for the list of all caches in this memcg
   * @root_cache: pointer to the global, root cache, this cache was derived from
   * @dead: set to true after the memcg dies; the cache may still be around.
   * @nr_pages: number of pages that belongs to this cache.
   * @destroy: worker to be called whenever we are ready, or believe we may be
   *           ready, to destroy this cache.
   */
  struct memcg_cache_params {
  	bool is_root_cache;
  	union {
  		struct kmem_cache *memcg_caches[0];
  		struct {
  			struct mem_cgroup *memcg;
  			struct list_head list;
  			struct kmem_cache *root_cache;
  			bool dead;
  			atomic_t nr_pages;
  			struct work_struct destroy;
  		};
  	};
  };
  
  int memcg_update_all_caches(int num_memcgs);
  
  struct seq_file;
  int cache_show(struct kmem_cache *s, struct seq_file *m);
  void print_slabinfo_header(struct seq_file *m);
  
  /**
   * kmalloc_array - allocate memory for an array.
   * @n: number of elements.
   * @size: element size.
   * @flags: the type of memory to allocate.
   *
   * The @flags argument may be one of:
   *
   * %GFP_USER - Allocate memory on behalf of user.  May sleep.
   *
   * %GFP_KERNEL - Allocate normal kernel ram.  May sleep.
   *
   * %GFP_ATOMIC - Allocation will not sleep.  May use emergency pools.
   *   For example, use this inside interrupt handlers.
   *
   * %GFP_HIGHUSER - Allocate pages from high memory.
   *
   * %GFP_NOIO - Do not do any I/O at all while trying to get memory.
   *
   * %GFP_NOFS - Do not make any fs calls while trying to get memory.
   *
   * %GFP_NOWAIT - Allocation will not sleep.
   *
   * %__GFP_THISNODE - Allocate node-local memory only.
   *
   * %GFP_DMA - Allocation suitable for DMA.
   *   Should only be used for kmalloc() caches. Otherwise, use a
   *   slab created with SLAB_DMA.
   *
   * Also it is possible to set different flags by OR'ing
   * in one or more of the following additional @flags:
   *
   * %__GFP_COLD - Request cache-cold pages instead of
   *   trying to return cache-warm pages.
   *
   * %__GFP_HIGH - This allocation has high priority and may use emergency pools.
   *
   * %__GFP_NOFAIL - Indicate that this allocation is in no way allowed to fail
   *   (think twice before using).
   *
   * %__GFP_NORETRY - If memory is not immediately available,
   *   then give up at once.
   *
   * %__GFP_NOWARN - If allocation fails, don't issue any warnings.
   *
   * %__GFP_REPEAT - If allocation fails initially, try once more before failing.
   *
   * There are other flags available as well, but these are not intended
   * for general use, and so are not documented here. For a full list of
   * potential flags, always refer to linux/gfp.h.
   */
  static inline void *kmalloc_array(size_t n, size_t size, gfp_t flags)
  {
  	if (size != 0 && n > SIZE_MAX / size)
  		return NULL;
  	return __kmalloc(n * size, flags);
  }
  
  /**
   * kcalloc - allocate memory for an array. The memory is set to zero.
   * @n: number of elements.
   * @size: element size.
   * @flags: the type of memory to allocate (see kmalloc).
   */
  static inline void *kcalloc(size_t n, size_t size, gfp_t flags)
  {
  	return kmalloc_array(n, size, flags | __GFP_ZERO);
  }
  
  #if !defined(CONFIG_NUMA) && !defined(CONFIG_SLOB)
  /**
   * kmalloc_node - allocate memory from a specific node
   * @size: how many bytes of memory are required.
   * @flags: the type of memory to allocate (see kcalloc).
   * @node: node to allocate from.
   *
   * kmalloc() for non-local nodes, used to allocate from a specific node
   * if available. Equivalent to kmalloc() in the non-NUMA single-node
   * case.
   */
  static inline void *kmalloc_node(size_t size, gfp_t flags, int node)
  {
  	return kmalloc(size, flags);
  }
  
  static inline void *__kmalloc_node(size_t size, gfp_t flags, int node)
  {
  	return __kmalloc(size, flags);
  }
  
  void *kmem_cache_alloc(struct kmem_cache *, gfp_t);
  
  static inline void *kmem_cache_alloc_node(struct kmem_cache *cachep,
  					gfp_t flags, int node)
  {
  	return kmem_cache_alloc(cachep, flags);
  }
  #endif /* !CONFIG_NUMA && !CONFIG_SLOB */
  
  /*
   * kmalloc_track_caller is a special version of kmalloc that records the
   * calling function of the routine calling it for slab leak tracking instead
   * of just the calling function (confusing, eh?).
   * It's useful when the call to kmalloc comes from a widely-used standard
   * allocator where we care about the real place the memory allocation
   * request comes from.
   */
  #if defined(CONFIG_DEBUG_SLAB) || defined(CONFIG_SLUB) || \
  	(defined(CONFIG_SLAB) && defined(CONFIG_TRACING)) || \
  	(defined(CONFIG_SLOB) && defined(CONFIG_TRACING))
  extern void *__kmalloc_track_caller(size_t, gfp_t, unsigned long);
  #define kmalloc_track_caller(size, flags) \
  	__kmalloc_track_caller(size, flags, _RET_IP_)
  #else
  #define kmalloc_track_caller(size, flags) \
  	__kmalloc(size, flags)
  #endif /* DEBUG_SLAB */
  
  #ifdef CONFIG_NUMA
  /*
   * kmalloc_node_track_caller is a special version of kmalloc_node that
   * records the calling function of the routine calling it for slab leak
   * tracking instead of just the calling function (confusing, eh?).
   * It's useful when the call to kmalloc_node comes from a widely-used
   * standard allocator where we care about the real place the memory
   * allocation request comes from.
   */
  #if defined(CONFIG_DEBUG_SLAB) || defined(CONFIG_SLUB) || \
  	(defined(CONFIG_SLAB) && defined(CONFIG_TRACING)) || \
  	(defined(CONFIG_SLOB) && defined(CONFIG_TRACING))
  extern void *__kmalloc_node_track_caller(size_t, gfp_t, int, unsigned long);
  #define kmalloc_node_track_caller(size, flags, node) \
  	__kmalloc_node_track_caller(size, flags, node, \
  			_RET_IP_)
  #else
  #define kmalloc_node_track_caller(size, flags, node) \
  	__kmalloc_node(size, flags, node)
  #endif
  
  #else /* CONFIG_NUMA */
  
  #define kmalloc_node_track_caller(size, flags, node) \
  	kmalloc_track_caller(size, flags)
  
  #endif /* CONFIG_NUMA */
  
  /*
   * Shortcuts
   */
  static inline void *kmem_cache_zalloc(struct kmem_cache *k, gfp_t flags)
  {
  	return kmem_cache_alloc(k, flags | __GFP_ZERO);
  }
  
  /**
   * kzalloc - allocate memory. The memory is set to zero.
   * @size: how many bytes of memory are required.
   * @flags: the type of memory to allocate (see kmalloc).
   */
  static inline void *kzalloc(size_t size, gfp_t flags)
  {
  	return kmalloc(size, flags | __GFP_ZERO);
  }
  
  /**
   * kzalloc_node - allocate zeroed memory from a particular memory node.
   * @size: how many bytes of memory are required.
   * @flags: the type of memory to allocate (see kmalloc).
   * @node: memory node from which to allocate
   */
  static inline void *kzalloc_node(size_t size, gfp_t flags, int node)
  {
  	return kmalloc_node(size, flags | __GFP_ZERO, node);
  }
  
  /*
   * Determine the size of a slab object
   */
  static inline unsigned int kmem_cache_size(struct kmem_cache *s)
  {
  	return s->object_size;
  }
  
  void __init kmem_cache_init_late(void);
  
  #endif	/* _LINUX_SLAB_H */
  