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
  74 /* The following flags affect the page allocator grouping pages by mobility */
  75 #define SLAB_RECLAIM_ACCOUNT    0x00020000UL            /* Objects are reclaimable */
  76 #define SLAB_TEMPORARY          SLAB_RECLAIM_ACCOUNT    /* Objects are short-lived */
  77 /*
  78  * ZERO_SIZE_PTR will be returned for zero sized kmalloc requests.
  79  *
  80  * Dereferencing ZERO_SIZE_PTR will lead to a distinct access fault.
  81  *
  82  * ZERO_SIZE_PTR can be passed to kfree though in the same way that NULL can.
  83  * Both make kfree a no-op.
  84  */
  85 #define ZERO_SIZE_PTR ((void *)16)
  86
  87 #define ZERO_OR_NULL_PTR(x) ((unsigned long)(x) <= \
  88                                 (unsigned long)ZERO_SIZE_PTR)
  89
  90 /*
  91  * struct kmem_cache related prototypes
  92  */
  93 void __init kmem_cache_init(void);
  94 int slab_is_available(void);
  95
  96 struct kmem_cache *kmem_cache_create(const char *, size_t, size_t,
  97                         unsigned long,
  98                         void (*)(void *));
  99 void kmem_cache_destroy(struct kmem_cache *);
 100 int kmem_cache_shrink(struct kmem_cache *);
 101 void kmem_cache_free(struct kmem_cache *, void *);
 102 unsigned int kmem_cache_size(struct kmem_cache *);
 103 const char *kmem_cache_name(struct kmem_cache *);
 104 int kmem_ptr_validate(struct kmem_cache *cachep, const void *ptr);
 105
 106 /*
 107  * Please use this macro to create slab caches. Simply specify the
 108  * name of the structure and maybe some flags that are listed above.
 109  *
 110  * The alignment of the struct determines object alignment. If you
 111  * f.e. add ____cacheline_aligned_in_smp to the struct declaration
 112  * then the objects will be properly aligned in SMP configurations.
 113  */
 114 #define KMEM_CACHE(__struct, __flags) kmem_cache_create(#__struct,\
 115                 sizeof(struct __struct), __alignof__(struct __struct),\
 116                 (__flags), NULL)
 117
 118 /*
 119  * The largest kmalloc size supported by the slab allocators is
 120  * 32 megabyte (2^25) or the maximum allocatable page order if that is
 121  * less than 32 MB.
 122  *
 123  * WARNING: Its not easy to increase this value since the allocators have
 124  * to do various tricks to work around compiler limitations in order to
 125  * ensure proper constant folding.
 126  */
 127 #define KMALLOC_SHIFT_HIGH      ((MAX_ORDER + PAGE_SHIFT - 1) <= 25 ? \
 128                                 (MAX_ORDER + PAGE_SHIFT - 1) : 25)
 129
 130 #define KMALLOC_MAX_SIZE        (1UL << KMALLOC_SHIFT_HIGH)
 131 #define KMALLOC_MAX_ORDER       (KMALLOC_SHIFT_HIGH - PAGE_SHIFT)
 132
 133 /*
 134  * Common kmalloc functions provided by all allocators
 135  */
 136 void * __must_check __krealloc(const void *, size_t, gfp_t);
 137 void * __must_check krealloc(const void *, size_t, gfp_t);
 138 void kfree(const void *);
 139 void kzfree(const void *);
 140 size_t ksize(const void *);
 141
 142 /*
 143  * Allocator specific definitions. These are mainly used to establish optimized
 144  * ways to convert kmalloc() calls to kmem_cache_alloc() invocations by
 145  * selecting the appropriate general cache at compile time.
 146  *
 147  * Allocators must define at least:
 148  *
 149  *      kmem_cache_alloc()
 150  *      __kmalloc()
 151  *      kmalloc()
 152  *
 153  * Those wishing to support NUMA must also define:
 154  *
 155  *      kmem_cache_alloc_node()
 156  *      kmalloc_node()
 157  *
 158  * See each allocator definition file for additional comments and
 159  * implementation notes.
 160  */
 161 #ifdef CONFIG_SLUB
 162 #include <linux/slub_def.h>
 163 #elif defined(CONFIG_SLOB)
 164 #include <linux/slob_def.h>
 165 #else
 166 #include <linux/slab_def.h>
 167 #endif
 168
 169 /**
 170  * kcalloc - allocate memory for an array. The memory is set to zero.
 171  * @n: number of elements.
 172  * @size: element size.
 173  * @flags: the type of memory to allocate.
 174  *
 175  * The @flags argument may be one of:
 176  *
 177  * %GFP_USER - Allocate memory on behalf of user.  May sleep.
 178  *
 179  * %GFP_KERNEL - Allocate normal kernel ram.  May sleep.
 180  *
 181  * %GFP_ATOMIC - Allocation will not sleep.  May use emergency pools.
 182  *   For example, use this inside interrupt handlers.
 183  *
 184  * %GFP_HIGHUSER - Allocate pages from high memory.
 185  *
 186  * %GFP_NOIO - Do not do any I/O at all while trying to get memory.
 187  *
 188  * %GFP_NOFS - Do not make any fs calls while trying to get memory.
 189  *
 190  * %GFP_NOWAIT - Allocation will not sleep.
 191  *
 192  * %GFP_THISNODE - Allocate node-local memory only.
 193  *
 194  * %GFP_DMA - Allocation suitable for DMA.
 195  *   Should only be used for kmalloc() caches. Otherwise, use a
 196  *   slab created with SLAB_DMA.
 197  *
 198  * Also it is possible to set different flags by OR'ing
 199  * in one or more of the following additional @flags:
 200  *
 201  * %__GFP_COLD - Request cache-cold pages instead of
 202  *   trying to return cache-warm pages.
 203  *
 204  * %__GFP_HIGH - This allocation has high priority and may use emergency pools.
 205  *
 206  * %__GFP_NOFAIL - Indicate that this allocation is in no way allowed to fail
 207  *   (think twice before using).
 208  *
 209  * %__GFP_NORETRY - If memory is not immediately available,
 210  *   then give up at once.
 211  *
 212  * %__GFP_NOWARN - If allocation fails, don't issue any warnings.
 213  *
 214  * %__GFP_REPEAT - If allocation fails initially, try once more before failing.
 215  *
 216  * There are other flags available as well, but these are not intended
 217  * for general use, and so are not documented here. For a full list of
 218  * potential flags, always refer to linux/gfp.h.
 219  */
 220 static inline void *kcalloc(size_t n, size_t size, gfp_t flags)
 221 {
 222         if (size != 0 && n > ULONG_MAX / size)
 223                 return NULL;
 224         return __kmalloc(n * size, flags | __GFP_ZERO);
 225 }
 226
 227 #if !defined(CONFIG_NUMA) && !defined(CONFIG_SLOB)
 228 /**
 229  * kmalloc_node - allocate memory from a specific node
 230  * @size: how many bytes of memory are required.
 231  * @flags: the type of memory to allocate (see kcalloc).
 232  * @node: node to allocate from.
 233  *
 234  * kmalloc() for non-local nodes, used to allocate from a specific node
 235  * if available. Equivalent to kmalloc() in the non-NUMA single-node
 236  * case.
 237  */
 238 static inline void *kmalloc_node(size_t size, gfp_t flags, int node)
 239 {
 240         return kmalloc(size, flags);
 241 }
 242
 243 static inline void *__kmalloc_node(size_t size, gfp_t flags, int node)
 244 {
 245         return __kmalloc(size, flags);
 246 }
 247
 248 void *kmem_cache_alloc(struct kmem_cache *, gfp_t);
 249
 250 static inline void *kmem_cache_alloc_node(struct kmem_cache *cachep,
 251                                         gfp_t flags, int node)
 252 {
 253         return kmem_cache_alloc(cachep, flags);
 254 }
 255 #endif /* !CONFIG_NUMA && !CONFIG_SLOB */
 256
 257 /*
 258  * kmalloc_track_caller is a special version of kmalloc that records the
 259  * calling function of the routine calling it for slab leak tracking instead
 260  * of just the calling function (confusing, eh?).
 261  * It's useful when the call to kmalloc comes from a widely-used standard
 262  * allocator where we care about the real place the memory allocation
 263  * request comes from.
 264  */
 265 #if defined(CONFIG_DEBUG_SLAB) || defined(CONFIG_SLUB)
 266 extern void *__kmalloc_track_caller(size_t, gfp_t, unsigned long);
 267 #define kmalloc_track_caller(size, flags) \
 268         __kmalloc_track_caller(size, flags, _RET_IP_)
 269 #else
 270 #define kmalloc_track_caller(size, flags) \
 271         __kmalloc(size, flags)
 272 #endif /* DEBUG_SLAB */
 273
 274 #ifdef CONFIG_NUMA
 275 /*
 276  * kmalloc_node_track_caller is a special version of kmalloc_node that
 277  * records the calling function of the routine calling it for slab leak
 278  * tracking instead of just the calling function (confusing, eh?).
 279  * It's useful when the call to kmalloc_node comes from a widely-used
 280  * standard allocator where we care about the real place the memory
 281  * allocation request comes from.
 282  */
 283 #if defined(CONFIG_DEBUG_SLAB) || defined(CONFIG_SLUB)
 284 extern void *__kmalloc_node_track_caller(size_t, gfp_t, int, unsigned long);
 285 #define kmalloc_node_track_caller(size, flags, node) \
 286         __kmalloc_node_track_caller(size, flags, node, \
 287                         _RET_IP_)
 288 #else
 289 #define kmalloc_node_track_caller(size, flags, node) \
 290         __kmalloc_node(size, flags, node)
 291 #endif
 292
 293 #else /* CONFIG_NUMA */
 294
 295 #define kmalloc_node_track_caller(size, flags, node) \
 296         kmalloc_track_caller(size, flags)
 297
 298 #endif /* CONFIG_NUMA */
 299
 300 /*
 301  * Shortcuts
 302  */
 303 static inline void *kmem_cache_zalloc(struct kmem_cache *k, gfp_t flags)
 304 {
 305         return kmem_cache_alloc(k, flags | __GFP_ZERO);
 306 }
 307
 308 /**
 309  * kzalloc - allocate memory. The memory is set to zero.
 310  * @size: how many bytes of memory are required.
 311  * @flags: the type of memory to allocate (see kmalloc).
 312  */
 313 static inline void *kzalloc(size_t size, gfp_t flags)
 314 {
 315         return kmalloc(size, flags | __GFP_ZERO);
 316 }
 317
 318 /**
 319  * kzalloc_node - allocate zeroed memory from a particular memory node.
 320  * @size: how many bytes of memory are required.
 321  * @flags: the type of memory to allocate (see kmalloc).
 322  * @node: memory node from which to allocate
 323  */
 324 static inline void *kzalloc_node(size_t size, gfp_t flags, int node)
 325 {
 326         return kmalloc_node(size, flags | __GFP_ZERO, node);
 327 }
 328
 329 void __init kmem_cache_init_late(void);
 330
 331 #endif  /* _LINUX_SLAB_H */