linux/include/linux/slab.h
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   1/*
   2 * Written by Mark Hemment, 1996 (markhe@nextd.demon.co.uk).
   3 *
   4 * (C) SGI 2006, Christoph Lameter
   5 *      Cleaned up and restructured to ease the addition of alternative
   6 *      implementations of SLAB allocators.
   7 */
   8
   9#ifndef _LINUX_SLAB_H
  10#define _LINUX_SLAB_H
  11
  12#include <linux/gfp.h>
  13#include <linux/types.h>
  14
  15/*
  16 * Flags to pass to kmem_cache_create().
  17 * The ones marked DEBUG are only valid if CONFIG_SLAB_DEBUG is set.
  18 */
  19#define SLAB_DEBUG_FREE         0x00000100UL    /* DEBUG: Perform (expensive) checks on free */
  20#define SLAB_RED_ZONE           0x00000400UL    /* DEBUG: Red zone objs in a cache */
  21#define SLAB_POISON             0x00000800UL    /* DEBUG: Poison objects */
  22#define SLAB_HWCACHE_ALIGN      0x00002000UL    /* Align objs on cache lines */
  23#define SLAB_CACHE_DMA          0x00004000UL    /* Use GFP_DMA memory */
  24#define SLAB_STORE_USER         0x00010000UL    /* DEBUG: Store the last owner for bug hunting */
  25#define SLAB_PANIC              0x00040000UL    /* Panic if kmem_cache_create() fails */
  26/*
  27 * SLAB_DESTROY_BY_RCU - **WARNING** READ THIS!
  28 *
  29 * This delays freeing the SLAB page by a grace period, it does _NOT_
  30 * delay object freeing. This means that if you do kmem_cache_free()
  31 * that memory location is free to be reused at any time. Thus it may
  32 * be possible to see another object there in the same RCU grace period.
  33 *
  34 * This feature only ensures the memory location backing the object
  35 * stays valid, the trick to using this is relying on an independent
  36 * object validation pass. Something like:
  37 *
  38 *  rcu_read_lock()
  39 * again:
  40 *  obj = lockless_lookup(key);
  41 *  if (obj) {
  42 *    if (!try_get_ref(obj)) // might fail for free objects
  43 *      goto again;
  44 *
  45 *    if (obj->key != key) { // not the object we expected
  46 *      put_ref(obj);
  47 *      goto again;
  48 *    }
  49 *  }
  50 *  rcu_read_unlock();
  51 *
  52 * See also the comment on struct slab_rcu in mm/slab.c.
  53 */
  54#define SLAB_DESTROY_BY_RCU     0x00080000UL    /* Defer freeing slabs to RCU */
  55#define SLAB_MEM_SPREAD         0x00100000UL    /* Spread some memory over cpuset */
  56#define SLAB_TRACE              0x00200000UL    /* Trace allocations and frees */
  57
  58/* Flag to prevent checks on free */
  59#ifdef CONFIG_DEBUG_OBJECTS
  60# define SLAB_DEBUG_OBJECTS     0x00400000UL
  61#else
  62# define SLAB_DEBUG_OBJECTS     0x00000000UL
  63#endif
  64
  65#define SLAB_NOLEAKTRACE        0x00800000UL    /* Avoid kmemleak tracing */
  66
  67/* Don't track use of uninitialized memory */
  68#ifdef CONFIG_KMEMCHECK
  69# define SLAB_NOTRACK           0x01000000UL
  70#else
  71# define SLAB_NOTRACK           0x00000000UL
  72#endif
  73#ifdef CONFIG_FAILSLAB
  74# define SLAB_FAILSLAB          0x02000000UL    /* Fault injection mark */
  75#else
  76# define SLAB_FAILSLAB          0x00000000UL
  77#endif
  78
  79/* The following flags affect the page allocator grouping pages by mobility */
  80#define SLAB_RECLAIM_ACCOUNT    0x00020000UL            /* Objects are reclaimable */
  81#define SLAB_TEMPORARY          SLAB_RECLAIM_ACCOUNT    /* Objects are short-lived */
  82/*
  83 * ZERO_SIZE_PTR will be returned for zero sized kmalloc requests.
  84 *
  85 * Dereferencing ZERO_SIZE_PTR will lead to a distinct access fault.
  86 *
  87 * ZERO_SIZE_PTR can be passed to kfree though in the same way that NULL can.
  88 * Both make kfree a no-op.
  89 */
  90#define ZERO_SIZE_PTR ((void *)16)
  91
  92#define ZERO_OR_NULL_PTR(x) ((unsigned long)(x) <= \
  93                                (unsigned long)ZERO_SIZE_PTR)
  94
  95/*
  96 * struct kmem_cache related prototypes
  97 */
  98void __init kmem_cache_init(void);
  99int slab_is_available(void);
 100
 101struct kmem_cache *kmem_cache_create(const char *, size_t, size_t,
 102                        unsigned long,
 103                        void (*)(void *));
 104void kmem_cache_destroy(struct kmem_cache *);
 105int kmem_cache_shrink(struct kmem_cache *);
 106void kmem_cache_free(struct kmem_cache *, void *);
 107unsigned int kmem_cache_size(struct kmem_cache *);
 108const char *kmem_cache_name(struct kmem_cache *);
 109int kern_ptr_validate(const void *ptr, unsigned long size);
 110int kmem_ptr_validate(struct kmem_cache *cachep, const void *ptr);
 111
 112/*
 113 * Please use this macro to create slab caches. Simply specify the
 114 * name of the structure and maybe some flags that are listed above.
 115 *
 116 * The alignment of the struct determines object alignment. If you
 117 * f.e. add ____cacheline_aligned_in_smp to the struct declaration
 118 * then the objects will be properly aligned in SMP configurations.
 119 */
 120#define KMEM_CACHE(__struct, __flags) kmem_cache_create(#__struct,\
 121                sizeof(struct __struct), __alignof__(struct __struct),\
 122                (__flags), NULL)
 123
 124/*
 125 * The largest kmalloc size supported by the slab allocators is
 126 * 32 megabyte (2^25) or the maximum allocatable page order if that is
 127 * less than 32 MB.
 128 *
 129 * WARNING: Its not easy to increase this value since the allocators have
 130 * to do various tricks to work around compiler limitations in order to
 131 * ensure proper constant folding.
 132 */
 133#define KMALLOC_SHIFT_HIGH      ((MAX_ORDER + PAGE_SHIFT - 1) <= 25 ? \
 134                                (MAX_ORDER + PAGE_SHIFT - 1) : 25)
 135
 136#define KMALLOC_MAX_SIZE        (1UL << KMALLOC_SHIFT_HIGH)
 137#define KMALLOC_MAX_ORDER       (KMALLOC_SHIFT_HIGH - PAGE_SHIFT)
 138
 139/*
 140 * Common kmalloc functions provided by all allocators
 141 */
 142void * __must_check __krealloc(const void *, size_t, gfp_t);
 143void * __must_check krealloc(const void *, size_t, gfp_t);
 144void kfree(const void *);
 145void kzfree(const void *);
 146size_t ksize(const void *);
 147
 148/*
 149 * Allocator specific definitions. These are mainly used to establish optimized
 150 * ways to convert kmalloc() calls to kmem_cache_alloc() invocations by
 151 * selecting the appropriate general cache at compile time.
 152 *
 153 * Allocators must define at least:
 154 *
 155 *      kmem_cache_alloc()
 156 *      __kmalloc()
 157 *      kmalloc()
 158 *
 159 * Those wishing to support NUMA must also define:
 160 *
 161 *      kmem_cache_alloc_node()
 162 *      kmalloc_node()
 163 *
 164 * See each allocator definition file for additional comments and
 165 * implementation notes.
 166 */
 167#ifdef CONFIG_SLUB
 168#include <linux/slub_def.h>
 169#elif defined(CONFIG_SLOB)
 170#include <linux/slob_def.h>
 171#else
 172#include <linux/slab_def.h>
 173#endif
 174
 175/**
 176 * kcalloc - allocate memory for an array. The memory is set to zero.
 177 * @n: number of elements.
 178 * @size: element size.
 179 * @flags: the type of memory to allocate.
 180 *
 181 * The @flags argument may be one of:
 182 *
 183 * %GFP_USER - Allocate memory on behalf of user.  May sleep.
 184 *
 185 * %GFP_KERNEL - Allocate normal kernel ram.  May sleep.
 186 *
 187 * %GFP_ATOMIC - Allocation will not sleep.  May use emergency pools.
 188 *   For example, use this inside interrupt handlers.
 189 *
 190 * %GFP_HIGHUSER - Allocate pages from high memory.
 191 *
 192 * %GFP_NOIO - Do not do any I/O at all while trying to get memory.
 193 *
 194 * %GFP_NOFS - Do not make any fs calls while trying to get memory.
 195 *
 196 * %GFP_NOWAIT - Allocation will not sleep.
 197 *
 198 * %GFP_THISNODE - Allocate node-local memory only.
 199 *
 200 * %GFP_DMA - Allocation suitable for DMA.
 201 *   Should only be used for kmalloc() caches. Otherwise, use a
 202 *   slab created with SLAB_DMA.
 203 *
 204 * Also it is possible to set different flags by OR'ing
 205 * in one or more of the following additional @flags:
 206 *
 207 * %__GFP_COLD - Request cache-cold pages instead of
 208 *   trying to return cache-warm pages.
 209 *
 210 * %__GFP_HIGH - This allocation has high priority and may use emergency pools.
 211 *
 212 * %__GFP_NOFAIL - Indicate that this allocation is in no way allowed to fail
 213 *   (think twice before using).
 214 *
 215 * %__GFP_NORETRY - If memory is not immediately available,
 216 *   then give up at once.
 217 *
 218 * %__GFP_NOWARN - If allocation fails, don't issue any warnings.
 219 *
 220 * %__GFP_REPEAT - If allocation fails initially, try once more before failing.
 221 *
 222 * There are other flags available as well, but these are not intended
 223 * for general use, and so are not documented here. For a full list of
 224 * potential flags, always refer to linux/gfp.h.
 225 */
 226static inline void *kcalloc(size_t n, size_t size, gfp_t flags)
 227{
 228        if (size != 0 && n > ULONG_MAX / size)
 229                return NULL;
 230        return __kmalloc(n * size, flags | __GFP_ZERO);
 231}
 232
 233#if !defined(CONFIG_NUMA) && !defined(CONFIG_SLOB)
 234/**
 235 * kmalloc_node - allocate memory from a specific node
 236 * @size: how many bytes of memory are required.
 237 * @flags: the type of memory to allocate (see kcalloc).
 238 * @node: node to allocate from.
 239 *
 240 * kmalloc() for non-local nodes, used to allocate from a specific node
 241 * if available. Equivalent to kmalloc() in the non-NUMA single-node
 242 * case.
 243 */
 244static inline void *kmalloc_node(size_t size, gfp_t flags, int node)
 245{
 246        return kmalloc(size, flags);
 247}
 248
 249static inline void *__kmalloc_node(size_t size, gfp_t flags, int node)
 250{
 251        return __kmalloc(size, flags);
 252}
 253
 254void *kmem_cache_alloc(struct kmem_cache *, gfp_t);
 255
 256static inline void *kmem_cache_alloc_node(struct kmem_cache *cachep,
 257                                        gfp_t flags, int node)
 258{
 259        return kmem_cache_alloc(cachep, flags);
 260}
 261#endif /* !CONFIG_NUMA && !CONFIG_SLOB */
 262
 263/*
 264 * kmalloc_track_caller is a special version of kmalloc that records the
 265 * calling function of the routine calling it for slab leak tracking instead
 266 * of just the calling function (confusing, eh?).
 267 * It's useful when the call to kmalloc comes from a widely-used standard
 268 * allocator where we care about the real place the memory allocation
 269 * request comes from.
 270 */
 271#if defined(CONFIG_DEBUG_SLAB) || defined(CONFIG_SLUB) || \
 272        (defined(CONFIG_SLAB) && defined(CONFIG_TRACING))
 273extern void *__kmalloc_track_caller(size_t, gfp_t, unsigned long);
 274#define kmalloc_track_caller(size, flags) \
 275        __kmalloc_track_caller(size, flags, _RET_IP_)
 276#else
 277#define kmalloc_track_caller(size, flags) \
 278        __kmalloc(size, flags)
 279#endif /* DEBUG_SLAB */
 280
 281#ifdef CONFIG_NUMA
 282/*
 283 * kmalloc_node_track_caller is a special version of kmalloc_node that
 284 * records the calling function of the routine calling it for slab leak
 285 * tracking instead of just the calling function (confusing, eh?).
 286 * It's useful when the call to kmalloc_node comes from a widely-used
 287 * standard allocator where we care about the real place the memory
 288 * allocation request comes from.
 289 */
 290#if defined(CONFIG_DEBUG_SLAB) || defined(CONFIG_SLUB) || \
 291        (defined(CONFIG_SLAB) && defined(CONFIG_TRACING))
 292extern void *__kmalloc_node_track_caller(size_t, gfp_t, int, unsigned long);
 293#define kmalloc_node_track_caller(size, flags, node) \
 294        __kmalloc_node_track_caller(size, flags, node, \
 295                        _RET_IP_)
 296#else
 297#define kmalloc_node_track_caller(size, flags, node) \
 298        __kmalloc_node(size, flags, node)
 299#endif
 300
 301#else /* CONFIG_NUMA */
 302
 303#define kmalloc_node_track_caller(size, flags, node) \
 304        kmalloc_track_caller(size, flags)
 305
 306#endif /* CONFIG_NUMA */
 307
 308/*
 309 * Shortcuts
 310 */
 311static inline void *kmem_cache_zalloc(struct kmem_cache *k, gfp_t flags)
 312{
 313        return kmem_cache_alloc(k, flags | __GFP_ZERO);
 314}
 315
 316/**
 317 * kzalloc - allocate memory. The memory is set to zero.
 318 * @size: how many bytes of memory are required.
 319 * @flags: the type of memory to allocate (see kmalloc).
 320 */
 321static inline void *kzalloc(size_t size, gfp_t flags)
 322{
 323        return kmalloc(size, flags | __GFP_ZERO);
 324}
 325
 326/**
 327 * kzalloc_node - allocate zeroed memory from a particular memory node.
 328 * @size: how many bytes of memory are required.
 329 * @flags: the type of memory to allocate (see kmalloc).
 330 * @node: memory node from which to allocate
 331 */
 332static inline void *kzalloc_node(size_t size, gfp_t flags, int node)
 333{
 334        return kmalloc_node(size, flags | __GFP_ZERO, node);
 335}
 336
 337void __init kmem_cache_init_late(void);
 338
 339#endif  /* _LINUX_SLAB_H */
 340
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