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 /* The following flags affect the page allocator grouping pages by mobility */
  68 #define SLAB_RECLAIM_ACCOUNT    0x00020000UL            /* Objects are reclaimable */
  69 #define SLAB_TEMPORARY          SLAB_RECLAIM_ACCOUNT    /* Objects are short-lived */
  70 /*
  71  * ZERO_SIZE_PTR will be returned for zero sized kmalloc requests.
  72  *
  73  * Dereferencing ZERO_SIZE_PTR will lead to a distinct access fault.
  74  *
  75  * ZERO_SIZE_PTR can be passed to kfree though in the same way that NULL can.
  76  * Both make kfree a no-op.
  77  */
  78 #define ZERO_SIZE_PTR ((void *)16)
  79
  80 #define ZERO_OR_NULL_PTR(x) ((unsigned long)(x) <= \
  81                                 (unsigned long)ZERO_SIZE_PTR)
  82
  83 /*
  84  * struct kmem_cache related prototypes
  85  */
  86 void __init kmem_cache_init(void);
  87 int slab_is_available(void);
  88
  89 struct kmem_cache *kmem_cache_create(const char *, size_t, size_t,
  90                         unsigned long,
  91                         void (*)(void *));
  92 void kmem_cache_destroy(struct kmem_cache *);
  93 int kmem_cache_shrink(struct kmem_cache *);
  94 void kmem_cache_free(struct kmem_cache *, void *);
  95 unsigned int kmem_cache_size(struct kmem_cache *);
  96 const char *kmem_cache_name(struct kmem_cache *);
  97 int kmem_ptr_validate(struct kmem_cache *cachep, const void *ptr);
  98
  99 /*
 100  * Please use this macro to create slab caches. Simply specify the
 101  * name of the structure and maybe some flags that are listed above.
 102  *
 103  * The alignment of the struct determines object alignment. If you
 104  * f.e. add ____cacheline_aligned_in_smp to the struct declaration
 105  * then the objects will be properly aligned in SMP configurations.
 106  */
 107 #define KMEM_CACHE(__struct, __flags) kmem_cache_create(#__struct,\
 108                 sizeof(struct __struct), __alignof__(struct __struct),\
 109                 (__flags), NULL)
 110
 111 /*
 112  * The largest kmalloc size supported by the slab allocators is
 113  * 32 megabyte (2^25) or the maximum allocatable page order if that is
 114  * less than 32 MB.
 115  *
 116  * WARNING: Its not easy to increase this value since the allocators have
 117  * to do various tricks to work around compiler limitations in order to
 118  * ensure proper constant folding.
 119  */
 120 #define KMALLOC_SHIFT_HIGH      ((MAX_ORDER + PAGE_SHIFT - 1) <= 25 ? \
 121                                 (MAX_ORDER + PAGE_SHIFT - 1) : 25)
 122
 123 #define KMALLOC_MAX_SIZE        (1UL << KMALLOC_SHIFT_HIGH)
 124 #define KMALLOC_MAX_ORDER       (KMALLOC_SHIFT_HIGH - PAGE_SHIFT)
 125
 126 /*
 127  * Common kmalloc functions provided by all allocators
 128  */
 129 void * __must_check __krealloc(const void *, size_t, gfp_t);
 130 void * __must_check krealloc(const void *, size_t, gfp_t);
 131 void kfree(const void *);
 132 void kzfree(const void *);
 133 size_t ksize(const void *);
 134
 135 /*
 136  * Allocator specific definitions. These are mainly used to establish optimized
 137  * ways to convert kmalloc() calls to kmem_cache_alloc() invocations by
 138  * selecting the appropriate general cache at compile time.
 139  *
 140  * Allocators must define at least:
 141  *
 142  *      kmem_cache_alloc()
 143  *      __kmalloc()
 144  *      kmalloc()
 145  *
 146  * Those wishing to support NUMA must also define:
 147  *
 148  *      kmem_cache_alloc_node()
 149  *      kmalloc_node()
 150  *
 151  * See each allocator definition file for additional comments and
 152  * implementation notes.
 153  */
 154 #ifdef CONFIG_SLUB
 155 #include <linux/slub_def.h>
 156 #elif defined(CONFIG_SLOB)
 157 #include <linux/slob_def.h>
 158 #else
 159 #include <linux/slab_def.h>
 160 #endif
 161
 162 /**
 163  * kcalloc - allocate memory for an array. The memory is set to zero.
 164  * @n: number of elements.
 165  * @size: element size.
 166  * @flags: the type of memory to allocate.
 167  *
 168  * The @flags argument may be one of:
 169  *
 170  * %GFP_USER - Allocate memory on behalf of user.  May sleep.
 171  *
 172  * %GFP_KERNEL - Allocate normal kernel ram.  May sleep.
 173  *
 174  * %GFP_ATOMIC - Allocation will not sleep.  May use emergency pools.
 175  *   For example, use this inside interrupt handlers.
 176  *
 177  * %GFP_HIGHUSER - Allocate pages from high memory.
 178  *
 179  * %GFP_NOIO - Do not do any I/O at all while trying to get memory.
 180  *
 181  * %GFP_NOFS - Do not make any fs calls while trying to get memory.
 182  *
 183  * %GFP_NOWAIT - Allocation will not sleep.
 184  *
 185  * %GFP_THISNODE - Allocate node-local memory only.
 186  *
 187  * %GFP_DMA - Allocation suitable for DMA.
 188  *   Should only be used for kmalloc() caches. Otherwise, use a
 189  *   slab created with SLAB_DMA.
 190  *
 191  * Also it is possible to set different flags by OR'ing
 192  * in one or more of the following additional @flags:
 193  *
 194  * %__GFP_COLD - Request cache-cold pages instead of
 195  *   trying to return cache-warm pages.
 196  *
 197  * %__GFP_HIGH - This allocation has high priority and may use emergency pools.
 198  *
 199  * %__GFP_NOFAIL - Indicate that this allocation is in no way allowed to fail
 200  *   (think twice before using).
 201  *
 202  * %__GFP_NORETRY - If memory is not immediately available,
 203  *   then give up at once.
 204  *
 205  * %__GFP_NOWARN - If allocation fails, don't issue any warnings.
 206  *
 207  * %__GFP_REPEAT - If allocation fails initially, try once more before failing.
 208  *
 209  * There are other flags available as well, but these are not intended
 210  * for general use, and so are not documented here. For a full list of
 211  * potential flags, always refer to linux/gfp.h.
 212  */
 213 static inline void *kcalloc(size_t n, size_t size, gfp_t flags)
 214 {
 215         if (size != 0 && n > ULONG_MAX / size)
 216                 return NULL;
 217         return __kmalloc(n * size, flags | __GFP_ZERO);
 218 }
 219
 220 #if !defined(CONFIG_NUMA) && !defined(CONFIG_SLOB)
 221 /**
 222  * kmalloc_node - allocate memory from a specific node
 223  * @size: how many bytes of memory are required.
 224  * @flags: the type of memory to allocate (see kcalloc).
 225  * @node: node to allocate from.
 226  *
 227  * kmalloc() for non-local nodes, used to allocate from a specific node
 228  * if available. Equivalent to kmalloc() in the non-NUMA single-node
 229  * case.
 230  */
 231 static inline void *kmalloc_node(size_t size, gfp_t flags, int node)
 232 {
 233         return kmalloc(size, flags);
 234 }
 235
 236 static inline void *__kmalloc_node(size_t size, gfp_t flags, int node)
 237 {
 238         return __kmalloc(size, flags);
 239 }
 240
 241 void *kmem_cache_alloc(struct kmem_cache *, gfp_t);
 242
 243 static inline void *kmem_cache_alloc_node(struct kmem_cache *cachep,
 244                                         gfp_t flags, int node)
 245 {
 246         return kmem_cache_alloc(cachep, flags);
 247 }
 248 #endif /* !CONFIG_NUMA && !CONFIG_SLOB */
 249
 250 /*
 251  * kmalloc_track_caller is a special version of kmalloc that records the
 252  * calling function of the routine calling it for slab leak tracking instead
 253  * of just the calling function (confusing, eh?).
 254  * It's useful when the call to kmalloc comes from a widely-used standard
 255  * allocator where we care about the real place the memory allocation
 256  * request comes from.
 257  */
 258 #if defined(CONFIG_DEBUG_SLAB) || defined(CONFIG_SLUB)
 259 extern void *__kmalloc_track_caller(size_t, gfp_t, unsigned long);
 260 #define kmalloc_track_caller(size, flags) \
 261         __kmalloc_track_caller(size, flags, _RET_IP_)
 262 #else
 263 #define kmalloc_track_caller(size, flags) \
 264         __kmalloc(size, flags)
 265 #endif /* DEBUG_SLAB */
 266
 267 #ifdef CONFIG_NUMA
 268 /*
 269  * kmalloc_node_track_caller is a special version of kmalloc_node that
 270  * records the calling function of the routine calling it for slab leak
 271  * tracking instead of just the calling function (confusing, eh?).
 272  * It's useful when the call to kmalloc_node comes from a widely-used
 273  * standard allocator where we care about the real place the memory
 274  * allocation request comes from.
 275  */
 276 #if defined(CONFIG_DEBUG_SLAB) || defined(CONFIG_SLUB)
 277 extern void *__kmalloc_node_track_caller(size_t, gfp_t, int, unsigned long);
 278 #define kmalloc_node_track_caller(size, flags, node) \
 279         __kmalloc_node_track_caller(size, flags, node, \
 280                         _RET_IP_)
 281 #else
 282 #define kmalloc_node_track_caller(size, flags, node) \
 283         __kmalloc_node(size, flags, node)
 284 #endif
 285
 286 #else /* CONFIG_NUMA */
 287
 288 #define kmalloc_node_track_caller(size, flags, node) \
 289         kmalloc_track_caller(size, flags)
 290
 291 #endif /* CONFIG_NUMA */
 292
 293 /*
 294  * Shortcuts
 295  */
 296 static inline void *kmem_cache_zalloc(struct kmem_cache *k, gfp_t flags)
 297 {
 298         return kmem_cache_alloc(k, flags | __GFP_ZERO);
 299 }
 300
 301 /**
 302  * kzalloc - allocate memory. The memory is set to zero.
 303  * @size: how many bytes of memory are required.
 304  * @flags: the type of memory to allocate (see kmalloc).
 305  */
 306 static inline void *kzalloc(size_t size, gfp_t flags)
 307 {
 308         return kmalloc(size, flags | __GFP_ZERO);
 309 }
 310
 311 /**
 312  * kzalloc_node - allocate zeroed memory from a particular memory node.
 313  * @size: how many bytes of memory are required.
 314  * @flags: the type of memory to allocate (see kmalloc).
 315  * @node: memory node from which to allocate
 316  */
 317 static inline void *kzalloc_node(size_t size, gfp_t flags, int node)
 318 {
 319         return kmalloc_node(size, flags | __GFP_ZERO, node);
 320 }
 321
 322 void __init kmem_cache_init_late(void);
 323
 324 #endif  /* _LINUX_SLAB_H */