linux/include/linux/slab.h
<<
>>
Prefs
   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 * Common fields provided in kmem_cache by all slab allocators
  97 * This struct is either used directly by the allocator (SLOB)
  98 * or the allocator must include definitions for all fields
  99 * provided in kmem_cache_common in their definition of kmem_cache.
 100 *
 101 * Once we can do anonymous structs (C11 standard) we could put a
 102 * anonymous struct definition in these allocators so that the
 103 * separate allocations in the kmem_cache structure of SLAB and
 104 * SLUB is no longer needed.
 105 */
 106#ifdef CONFIG_SLOB
 107struct kmem_cache {
 108        unsigned int object_size;/* The original size of the object */
 109        unsigned int size;      /* The aligned/padded/added on size  */
 110        unsigned int align;     /* Alignment as calculated */
 111        unsigned long flags;    /* Active flags on the slab */
 112        const char *name;       /* Slab name for sysfs */
 113        int refcount;           /* Use counter */
 114        void (*ctor)(void *);   /* Called on object slot creation */
 115        struct list_head list;  /* List of all slab caches on the system */
 116};
 117#endif
 118
 119/*
 120 * struct kmem_cache related prototypes
 121 */
 122void __init kmem_cache_init(void);
 123int slab_is_available(void);
 124
 125struct kmem_cache *kmem_cache_create(const char *, size_t, size_t,
 126                        unsigned long,
 127                        void (*)(void *));
 128void kmem_cache_destroy(struct kmem_cache *);
 129int kmem_cache_shrink(struct kmem_cache *);
 130void kmem_cache_free(struct kmem_cache *, void *);
 131unsigned int kmem_cache_size(struct kmem_cache *);
 132
 133/*
 134 * Please use this macro to create slab caches. Simply specify the
 135 * name of the structure and maybe some flags that are listed above.
 136 *
 137 * The alignment of the struct determines object alignment. If you
 138 * f.e. add ____cacheline_aligned_in_smp to the struct declaration
 139 * then the objects will be properly aligned in SMP configurations.
 140 */
 141#define KMEM_CACHE(__struct, __flags) kmem_cache_create(#__struct,\
 142                sizeof(struct __struct), __alignof__(struct __struct),\
 143                (__flags), NULL)
 144
 145/*
 146 * The largest kmalloc size supported by the slab allocators is
 147 * 32 megabyte (2^25) or the maximum allocatable page order if that is
 148 * less than 32 MB.
 149 *
 150 * WARNING: Its not easy to increase this value since the allocators have
 151 * to do various tricks to work around compiler limitations in order to
 152 * ensure proper constant folding.
 153 */
 154#define KMALLOC_SHIFT_HIGH      ((MAX_ORDER + PAGE_SHIFT - 1) <= 25 ? \
 155                                (MAX_ORDER + PAGE_SHIFT - 1) : 25)
 156
 157#define KMALLOC_MAX_SIZE        (1UL << KMALLOC_SHIFT_HIGH)
 158#define KMALLOC_MAX_ORDER       (KMALLOC_SHIFT_HIGH - PAGE_SHIFT)
 159
 160/*
 161 * Some archs want to perform DMA into kmalloc caches and need a guaranteed
 162 * alignment larger than the alignment of a 64-bit integer.
 163 * Setting ARCH_KMALLOC_MINALIGN in arch headers allows that.
 164 */
 165#ifdef ARCH_DMA_MINALIGN
 166#define ARCH_KMALLOC_MINALIGN ARCH_DMA_MINALIGN
 167#else
 168#define ARCH_KMALLOC_MINALIGN __alignof__(unsigned long long)
 169#endif
 170
 171/*
 172 * Setting ARCH_SLAB_MINALIGN in arch headers allows a different alignment.
 173 * Intended for arches that get misalignment faults even for 64 bit integer
 174 * aligned buffers.
 175 */
 176#ifndef ARCH_SLAB_MINALIGN
 177#define ARCH_SLAB_MINALIGN __alignof__(unsigned long long)
 178#endif
 179
 180/*
 181 * Common kmalloc functions provided by all allocators
 182 */
 183void * __must_check __krealloc(const void *, size_t, gfp_t);
 184void * __must_check krealloc(const void *, size_t, gfp_t);
 185void kfree(const void *);
 186void kzfree(const void *);
 187size_t ksize(const void *);
 188
 189/*
 190 * Allocator specific definitions. These are mainly used to establish optimized
 191 * ways to convert kmalloc() calls to kmem_cache_alloc() invocations by
 192 * selecting the appropriate general cache at compile time.
 193 *
 194 * Allocators must define at least:
 195 *
 196 *      kmem_cache_alloc()
 197 *      __kmalloc()
 198 *      kmalloc()
 199 *
 200 * Those wishing to support NUMA must also define:
 201 *
 202 *      kmem_cache_alloc_node()
 203 *      kmalloc_node()
 204 *
 205 * See each allocator definition file for additional comments and
 206 * implementation notes.
 207 */
 208#ifdef CONFIG_SLUB
 209#include <linux/slub_def.h>
 210#elif defined(CONFIG_SLOB)
 211#include <linux/slob_def.h>
 212#else
 213#include <linux/slab_def.h>
 214#endif
 215
 216/**
 217 * kmalloc_array - allocate memory for an array.
 218 * @n: number of elements.
 219 * @size: element size.
 220 * @flags: the type of memory to allocate.
 221 *
 222 * The @flags argument may be one of:
 223 *
 224 * %GFP_USER - Allocate memory on behalf of user.  May sleep.
 225 *
 226 * %GFP_KERNEL - Allocate normal kernel ram.  May sleep.
 227 *
 228 * %GFP_ATOMIC - Allocation will not sleep.  May use emergency pools.
 229 *   For example, use this inside interrupt handlers.
 230 *
 231 * %GFP_HIGHUSER - Allocate pages from high memory.
 232 *
 233 * %GFP_NOIO - Do not do any I/O at all while trying to get memory.
 234 *
 235 * %GFP_NOFS - Do not make any fs calls while trying to get memory.
 236 *
 237 * %GFP_NOWAIT - Allocation will not sleep.
 238 *
 239 * %GFP_THISNODE - Allocate node-local memory only.
 240 *
 241 * %GFP_DMA - Allocation suitable for DMA.
 242 *   Should only be used for kmalloc() caches. Otherwise, use a
 243 *   slab created with SLAB_DMA.
 244 *
 245 * Also it is possible to set different flags by OR'ing
 246 * in one or more of the following additional @flags:
 247 *
 248 * %__GFP_COLD - Request cache-cold pages instead of
 249 *   trying to return cache-warm pages.
 250 *
 251 * %__GFP_HIGH - This allocation has high priority and may use emergency pools.
 252 *
 253 * %__GFP_NOFAIL - Indicate that this allocation is in no way allowed to fail
 254 *   (think twice before using).
 255 *
 256 * %__GFP_NORETRY - If memory is not immediately available,
 257 *   then give up at once.
 258 *
 259 * %__GFP_NOWARN - If allocation fails, don't issue any warnings.
 260 *
 261 * %__GFP_REPEAT - If allocation fails initially, try once more before failing.
 262 *
 263 * There are other flags available as well, but these are not intended
 264 * for general use, and so are not documented here. For a full list of
 265 * potential flags, always refer to linux/gfp.h.
 266 */
 267static inline void *kmalloc_array(size_t n, size_t size, gfp_t flags)
 268{
 269        if (size != 0 && n > SIZE_MAX / size)
 270                return NULL;
 271        return __kmalloc(n * size, flags);
 272}
 273
 274/**
 275 * kcalloc - allocate memory for an array. The memory is set to zero.
 276 * @n: number of elements.
 277 * @size: element size.
 278 * @flags: the type of memory to allocate (see kmalloc).
 279 */
 280static inline void *kcalloc(size_t n, size_t size, gfp_t flags)
 281{
 282        return kmalloc_array(n, size, flags | __GFP_ZERO);
 283}
 284
 285#if !defined(CONFIG_NUMA) && !defined(CONFIG_SLOB)
 286/**
 287 * kmalloc_node - allocate memory from a specific node
 288 * @size: how many bytes of memory are required.
 289 * @flags: the type of memory to allocate (see kcalloc).
 290 * @node: node to allocate from.
 291 *
 292 * kmalloc() for non-local nodes, used to allocate from a specific node
 293 * if available. Equivalent to kmalloc() in the non-NUMA single-node
 294 * case.
 295 */
 296static inline void *kmalloc_node(size_t size, gfp_t flags, int node)
 297{
 298        return kmalloc(size, flags);
 299}
 300
 301static inline void *__kmalloc_node(size_t size, gfp_t flags, int node)
 302{
 303        return __kmalloc(size, flags);
 304}
 305
 306void *kmem_cache_alloc(struct kmem_cache *, gfp_t);
 307
 308static inline void *kmem_cache_alloc_node(struct kmem_cache *cachep,
 309                                        gfp_t flags, int node)
 310{
 311        return kmem_cache_alloc(cachep, flags);
 312}
 313#endif /* !CONFIG_NUMA && !CONFIG_SLOB */
 314
 315/*
 316 * kmalloc_track_caller is a special version of kmalloc that records the
 317 * calling function of the routine calling it for slab leak tracking instead
 318 * of just the calling function (confusing, eh?).
 319 * It's useful when the call to kmalloc comes from a widely-used standard
 320 * allocator where we care about the real place the memory allocation
 321 * request comes from.
 322 */
 323#if defined(CONFIG_DEBUG_SLAB) || defined(CONFIG_SLUB) || \
 324        (defined(CONFIG_SLAB) && defined(CONFIG_TRACING))
 325extern void *__kmalloc_track_caller(size_t, gfp_t, unsigned long);
 326#define kmalloc_track_caller(size, flags) \
 327        __kmalloc_track_caller(size, flags, _RET_IP_)
 328#else
 329#define kmalloc_track_caller(size, flags) \
 330        __kmalloc(size, flags)
 331#endif /* DEBUG_SLAB */
 332
 333#ifdef CONFIG_NUMA
 334/*
 335 * kmalloc_node_track_caller is a special version of kmalloc_node that
 336 * records the calling function of the routine calling it for slab leak
 337 * tracking instead of just the calling function (confusing, eh?).
 338 * It's useful when the call to kmalloc_node comes from a widely-used
 339 * standard allocator where we care about the real place the memory
 340 * allocation request comes from.
 341 */
 342#if defined(CONFIG_DEBUG_SLAB) || defined(CONFIG_SLUB) || \
 343        (defined(CONFIG_SLAB) && defined(CONFIG_TRACING))
 344extern void *__kmalloc_node_track_caller(size_t, gfp_t, int, unsigned long);
 345#define kmalloc_node_track_caller(size, flags, node) \
 346        __kmalloc_node_track_caller(size, flags, node, \
 347                        _RET_IP_)
 348#else
 349#define kmalloc_node_track_caller(size, flags, node) \
 350        __kmalloc_node(size, flags, node)
 351#endif
 352
 353#else /* CONFIG_NUMA */
 354
 355#define kmalloc_node_track_caller(size, flags, node) \
 356        kmalloc_track_caller(size, flags)
 357
 358#endif /* CONFIG_NUMA */
 359
 360/*
 361 * Shortcuts
 362 */
 363static inline void *kmem_cache_zalloc(struct kmem_cache *k, gfp_t flags)
 364{
 365        return kmem_cache_alloc(k, flags | __GFP_ZERO);
 366}
 367
 368/**
 369 * kzalloc - allocate memory. The memory is set to zero.
 370 * @size: how many bytes of memory are required.
 371 * @flags: the type of memory to allocate (see kmalloc).
 372 */
 373static inline void *kzalloc(size_t size, gfp_t flags)
 374{
 375        return kmalloc(size, flags | __GFP_ZERO);
 376}
 377
 378/**
 379 * kzalloc_node - allocate zeroed memory from a particular memory node.
 380 * @size: how many bytes of memory are required.
 381 * @flags: the type of memory to allocate (see kmalloc).
 382 * @node: memory node from which to allocate
 383 */
 384static inline void *kzalloc_node(size_t size, gfp_t flags, int node)
 385{
 386        return kmalloc_node(size, flags | __GFP_ZERO, node);
 387}
 388
 389void __init kmem_cache_init_late(void);
 390
 391#endif  /* _LINUX_SLAB_H */
 392
lxr.linux.no kindly hosted by Redpill Linpro AS, provider of Linux consulting and operations services since 1995.