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  * 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
 107 struct 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  */
 122 void __init kmem_cache_init(void);
 123 int slab_is_available(void);
 124
 125 struct kmem_cache *kmem_cache_create(const char *, size_t, size_t,
 126                         unsigned long,
 127                         void (*)(void *));
 128 void kmem_cache_destroy(struct kmem_cache *);
 129 int kmem_cache_shrink(struct kmem_cache *);
 130 void kmem_cache_free(struct kmem_cache *, void *);
 131 unsigned 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  */
 183 void * __must_check __krealloc(const void *, size_t, gfp_t);
 184 void * __must_check krealloc(const void *, size_t, gfp_t);
 185 void kfree(const void *);
 186 void kzfree(const void *);
 187 size_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  */
 267 static 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  */
 280 static 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  */
 296 static inline void *kmalloc_node(size_t size, gfp_t flags, int node)
 297 {
 298         return kmalloc(size, flags);
 299 }
 300
 301 static inline void *__kmalloc_node(size_t size, gfp_t flags, int node)
 302 {
 303         return __kmalloc(size, flags);
 304 }
 305
 306 void *kmem_cache_alloc(struct kmem_cache *, gfp_t);
 307
 308 static 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))
 325 extern 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))
 344 extern 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  */
 363 static 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  */
 373 static 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  */
 384 static inline void *kzalloc_node(size_t size, gfp_t flags, int node)
 385 {
 386         return kmalloc_node(size, flags | __GFP_ZERO, node);
 387 }
 388
 389 void __init kmem_cache_init_late(void);
 390
 391 #endif  /* _LINUX_SLAB_H */