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 /* The following flags affect the page allocator grouping pages by mobility */
  66 #define SLAB_RECLAIM_ACCOUNT    0x00020000UL            /* Objects are reclaimable */
  67 #define SLAB_TEMPORARY          SLAB_RECLAIM_ACCOUNT    /* Objects are short-lived */
  68 /*
  69  * ZERO_SIZE_PTR will be returned for zero sized kmalloc requests.
  70  *
  71  * Dereferencing ZERO_SIZE_PTR will lead to a distinct access fault.
  72  *
  73  * ZERO_SIZE_PTR can be passed to kfree though in the same way that NULL can.
  74  * Both make kfree a no-op.
  75  */
  76 #define ZERO_SIZE_PTR ((void *)16)
  77
  78 #define ZERO_OR_NULL_PTR(x) ((unsigned long)(x) <= \
  79                                 (unsigned long)ZERO_SIZE_PTR)
  80
  81 /*
  82  * struct kmem_cache related prototypes
  83  */
  84 void __init kmem_cache_init(void);
  85 int slab_is_available(void);
  86
  87 struct kmem_cache *kmem_cache_create(const char *, size_t, size_t,
  88                         unsigned long,
  89                         void (*)(void *));
  90 void kmem_cache_destroy(struct kmem_cache *);
  91 int kmem_cache_shrink(struct kmem_cache *);
  92 void kmem_cache_free(struct kmem_cache *, void *);
  93 unsigned int kmem_cache_size(struct kmem_cache *);
  94 const char *kmem_cache_name(struct kmem_cache *);
  95 int kmem_ptr_validate(struct kmem_cache *cachep, const void *ptr);
  96
  97 /*
  98  * Please use this macro to create slab caches. Simply specify the
  99  * name of the structure and maybe some flags that are listed above.
 100  *
 101  * The alignment of the struct determines object alignment. If you
 102  * f.e. add ____cacheline_aligned_in_smp to the struct declaration
 103  * then the objects will be properly aligned in SMP configurations.
 104  */
 105 #define KMEM_CACHE(__struct, __flags) kmem_cache_create(#__struct,\
 106                 sizeof(struct __struct), __alignof__(struct __struct),\
 107                 (__flags), NULL)
 108
 109 /*
 110  * The largest kmalloc size supported by the slab allocators is
 111  * 32 megabyte (2^25) or the maximum allocatable page order if that is
 112  * less than 32 MB.
 113  *
 114  * WARNING: Its not easy to increase this value since the allocators have
 115  * to do various tricks to work around compiler limitations in order to
 116  * ensure proper constant folding.
 117  */
 118 #define KMALLOC_SHIFT_HIGH      ((MAX_ORDER + PAGE_SHIFT - 1) <= 25 ? \
 119                                 (MAX_ORDER + PAGE_SHIFT - 1) : 25)
 120
 121 #define KMALLOC_MAX_SIZE        (1UL << KMALLOC_SHIFT_HIGH)
 122 #define KMALLOC_MAX_ORDER       (KMALLOC_SHIFT_HIGH - PAGE_SHIFT)
 123
 124 /*
 125  * Common kmalloc functions provided by all allocators
 126  */
 127 void * __must_check __krealloc(const void *, size_t, gfp_t);
 128 void * __must_check krealloc(const void *, size_t, gfp_t);
 129 void kfree(const void *);
 130 size_t ksize(const void *);
 131
 132 /*
 133  * Allocator specific definitions. These are mainly used to establish optimized
 134  * ways to convert kmalloc() calls to kmem_cache_alloc() invocations by
 135  * selecting the appropriate general cache at compile time.
 136  *
 137  * Allocators must define at least:
 138  *
 139  *      kmem_cache_alloc()
 140  *      __kmalloc()
 141  *      kmalloc()
 142  *
 143  * Those wishing to support NUMA must also define:
 144  *
 145  *      kmem_cache_alloc_node()
 146  *      kmalloc_node()
 147  *
 148  * See each allocator definition file for additional comments and
 149  * implementation notes.
 150  */
 151 #ifdef CONFIG_SLUB
 152 #include <linux/slub_def.h>
 153 #elif defined(CONFIG_SLOB)
 154 #include <linux/slob_def.h>
 155 #else
 156 #include <linux/slab_def.h>
 157 #endif
 158
 159 /**
 160  * kcalloc - allocate memory for an array. The memory is set to zero.
 161  * @n: number of elements.
 162  * @size: element size.
 163  * @flags: the type of memory to allocate.
 164  *
 165  * The @flags argument may be one of:
 166  *
 167  * %GFP_USER - Allocate memory on behalf of user.  May sleep.
 168  *
 169  * %GFP_KERNEL - Allocate normal kernel ram.  May sleep.
 170  *
 171  * %GFP_ATOMIC - Allocation will not sleep.  May use emergency pools.
 172  *   For example, use this inside interrupt handlers.
 173  *
 174  * %GFP_HIGHUSER - Allocate pages from high memory.
 175  *
 176  * %GFP_NOIO - Do not do any I/O at all while trying to get memory.
 177  *
 178  * %GFP_NOFS - Do not make any fs calls while trying to get memory.
 179  *
 180  * %GFP_NOWAIT - Allocation will not sleep.
 181  *
 182  * %GFP_THISNODE - Allocate node-local memory only.
 183  *
 184  * %GFP_DMA - Allocation suitable for DMA.
 185  *   Should only be used for kmalloc() caches. Otherwise, use a
 186  *   slab created with SLAB_DMA.
 187  *
 188  * Also it is possible to set different flags by OR'ing
 189  * in one or more of the following additional @flags:
 190  *
 191  * %__GFP_COLD - Request cache-cold pages instead of
 192  *   trying to return cache-warm pages.
 193  *
 194  * %__GFP_HIGH - This allocation has high priority and may use emergency pools.
 195  *
 196  * %__GFP_NOFAIL - Indicate that this allocation is in no way allowed to fail
 197  *   (think twice before using).
 198  *
 199  * %__GFP_NORETRY - If memory is not immediately available,
 200  *   then give up at once.
 201  *
 202  * %__GFP_NOWARN - If allocation fails, don't issue any warnings.
 203  *
 204  * %__GFP_REPEAT - If allocation fails initially, try once more before failing.
 205  *
 206  * There are other flags available as well, but these are not intended
 207  * for general use, and so are not documented here. For a full list of
 208  * potential flags, always refer to linux/gfp.h.
 209  */
 210 static inline void *kcalloc(size_t n, size_t size, gfp_t flags)
 211 {
 212         if (size != 0 && n > ULONG_MAX / size)
 213                 return NULL;
 214         return __kmalloc(n * size, flags | __GFP_ZERO);
 215 }
 216
 217 #if !defined(CONFIG_NUMA) && !defined(CONFIG_SLOB)
 218 /**
 219  * kmalloc_node - allocate memory from a specific node
 220  * @size: how many bytes of memory are required.
 221  * @flags: the type of memory to allocate (see kcalloc).
 222  * @node: node to allocate from.
 223  *
 224  * kmalloc() for non-local nodes, used to allocate from a specific node
 225  * if available. Equivalent to kmalloc() in the non-NUMA single-node
 226  * case.
 227  */
 228 static inline void *kmalloc_node(size_t size, gfp_t flags, int node)
 229 {
 230         return kmalloc(size, flags);
 231 }
 232
 233 static inline void *__kmalloc_node(size_t size, gfp_t flags, int node)
 234 {
 235         return __kmalloc(size, flags);
 236 }
 237
 238 void *kmem_cache_alloc(struct kmem_cache *, gfp_t);
 239
 240 static inline void *kmem_cache_alloc_node(struct kmem_cache *cachep,
 241                                         gfp_t flags, int node)
 242 {
 243         return kmem_cache_alloc(cachep, flags);
 244 }
 245 #endif /* !CONFIG_NUMA && !CONFIG_SLOB */
 246
 247 /*
 248  * kmalloc_track_caller is a special version of kmalloc that records the
 249  * calling function of the routine calling it for slab leak tracking instead
 250  * of just the calling function (confusing, eh?).
 251  * It's useful when the call to kmalloc comes from a widely-used standard
 252  * allocator where we care about the real place the memory allocation
 253  * request comes from.
 254  */
 255 #if defined(CONFIG_DEBUG_SLAB) || defined(CONFIG_SLUB)
 256 extern void *__kmalloc_track_caller(size_t, gfp_t, unsigned long);
 257 #define kmalloc_track_caller(size, flags) \
 258         __kmalloc_track_caller(size, flags, _RET_IP_)
 259 #else
 260 #define kmalloc_track_caller(size, flags) \
 261         __kmalloc(size, flags)
 262 #endif /* DEBUG_SLAB */
 263
 264 #ifdef CONFIG_NUMA
 265 /*
 266  * kmalloc_node_track_caller is a special version of kmalloc_node that
 267  * records the calling function of the routine calling it for slab leak
 268  * tracking instead of just the calling function (confusing, eh?).
 269  * It's useful when the call to kmalloc_node comes from a widely-used
 270  * standard allocator where we care about the real place the memory
 271  * allocation request comes from.
 272  */
 273 #if defined(CONFIG_DEBUG_SLAB) || defined(CONFIG_SLUB)
 274 extern void *__kmalloc_node_track_caller(size_t, gfp_t, int, unsigned long);
 275 #define kmalloc_node_track_caller(size, flags, node) \
 276         __kmalloc_node_track_caller(size, flags, node, \
 277                         _RET_IP_)
 278 #else
 279 #define kmalloc_node_track_caller(size, flags, node) \
 280         __kmalloc_node(size, flags, node)
 281 #endif
 282
 283 #else /* CONFIG_NUMA */
 284
 285 #define kmalloc_node_track_caller(size, flags, node) \
 286         kmalloc_track_caller(size, flags)
 287
 288 #endif /* CONFIG_NUMA */
 289
 290 /*
 291  * Shortcuts
 292  */
 293 static inline void *kmem_cache_zalloc(struct kmem_cache *k, gfp_t flags)
 294 {
 295         return kmem_cache_alloc(k, flags | __GFP_ZERO);
 296 }
 297
 298 /**
 299  * kzalloc - allocate memory. The memory is set to zero.
 300  * @size: how many bytes of memory are required.
 301  * @flags: the type of memory to allocate (see kmalloc).
 302  */
 303 static inline void *kzalloc(size_t size, gfp_t flags)
 304 {
 305         return kmalloc(size, flags | __GFP_ZERO);
 306 }
 307
 308 /**
 309  * kzalloc_node - allocate zeroed memory from a particular memory node.
 310  * @size: how many bytes of memory are required.
 311  * @flags: the type of memory to allocate (see kmalloc).
 312  * @node: memory node from which to allocate
 313  */
 314 static inline void *kzalloc_node(size_t size, gfp_t flags, int node)
 315 {
 316         return kmalloc_node(size, flags | __GFP_ZERO, node);
 317 }
 318
 319 #endif  /* _LINUX_SLAB_H */