include/linux/slab.h

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