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TOMOYO Linux Cross Reference
Linux/include/linux/slab.h

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  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 #include <linux/workqueue.h>
 15 
 16 
 17 /*
 18  * Flags to pass to kmem_cache_create().
 19  * The ones marked DEBUG are only valid if CONFIG_SLAB_DEBUG is set.
 20  */
 21 #define SLAB_DEBUG_FREE         0x00000100UL    /* DEBUG: Perform (expensive) checks on free */
 22 #define SLAB_RED_ZONE           0x00000400UL    /* DEBUG: Red zone objs in a cache */
 23 #define SLAB_POISON             0x00000800UL    /* DEBUG: Poison objects */
 24 #define SLAB_HWCACHE_ALIGN      0x00002000UL    /* Align objs on cache lines */
 25 #define SLAB_CACHE_DMA          0x00004000UL    /* Use GFP_DMA memory */
 26 #define SLAB_STORE_USER         0x00010000UL    /* DEBUG: Store the last owner for bug hunting */
 27 #define SLAB_PANIC              0x00040000UL    /* Panic if kmem_cache_create() fails */
 28 /*
 29  * SLAB_DESTROY_BY_RCU - **WARNING** READ THIS!
 30  *
 31  * This delays freeing the SLAB page by a grace period, it does _NOT_
 32  * delay object freeing. This means that if you do kmem_cache_free()
 33  * that memory location is free to be reused at any time. Thus it may
 34  * be possible to see another object there in the same RCU grace period.
 35  *
 36  * This feature only ensures the memory location backing the object
 37  * stays valid, the trick to using this is relying on an independent
 38  * object validation pass. Something like:
 39  *
 40  *  rcu_read_lock()
 41  * again:
 42  *  obj = lockless_lookup(key);
 43  *  if (obj) {
 44  *    if (!try_get_ref(obj)) // might fail for free objects
 45  *      goto again;
 46  *
 47  *    if (obj->key != key) { // not the object we expected
 48  *      put_ref(obj);
 49  *      goto again;
 50  *    }
 51  *  }
 52  *  rcu_read_unlock();
 53  *
 54  * See also the comment on struct slab_rcu in mm/slab.c.
 55  */
 56 #define SLAB_DESTROY_BY_RCU     0x00080000UL    /* Defer freeing slabs to RCU */
 57 #define SLAB_MEM_SPREAD         0x00100000UL    /* Spread some memory over cpuset */
 58 #define SLAB_TRACE              0x00200000UL    /* Trace allocations and frees */
 59 
 60 /* Flag to prevent checks on free */
 61 #ifdef CONFIG_DEBUG_OBJECTS
 62 # define SLAB_DEBUG_OBJECTS     0x00400000UL
 63 #else
 64 # define SLAB_DEBUG_OBJECTS     0x00000000UL
 65 #endif
 66 
 67 #define SLAB_NOLEAKTRACE        0x00800000UL    /* Avoid kmemleak tracing */
 68 
 69 /* Don't track use of uninitialized memory */
 70 #ifdef CONFIG_KMEMCHECK
 71 # define SLAB_NOTRACK           0x01000000UL
 72 #else
 73 # define SLAB_NOTRACK           0x00000000UL
 74 #endif
 75 #ifdef CONFIG_FAILSLAB
 76 # define SLAB_FAILSLAB          0x02000000UL    /* Fault injection mark */
 77 #else
 78 # define SLAB_FAILSLAB          0x00000000UL
 79 #endif
 80 
 81 /* The following flags affect the page allocator grouping pages by mobility */
 82 #define SLAB_RECLAIM_ACCOUNT    0x00020000UL            /* Objects are reclaimable */
 83 #define SLAB_TEMPORARY          SLAB_RECLAIM_ACCOUNT    /* Objects are short-lived */
 84 /*
 85  * ZERO_SIZE_PTR will be returned for zero sized kmalloc requests.
 86  *
 87  * Dereferencing ZERO_SIZE_PTR will lead to a distinct access fault.
 88  *
 89  * ZERO_SIZE_PTR can be passed to kfree though in the same way that NULL can.
 90  * Both make kfree a no-op.
 91  */
 92 #define ZERO_SIZE_PTR ((void *)16)
 93 
 94 #define ZERO_OR_NULL_PTR(x) ((unsigned long)(x) <= \
 95                                 (unsigned long)ZERO_SIZE_PTR)
 96 
 97 /*
 98  * Common fields provided in kmem_cache by all slab allocators
 99  * This struct is either used directly by the allocator (SLOB)
100  * or the allocator must include definitions for all fields
101  * provided in kmem_cache_common in their definition of kmem_cache.
102  *
103  * Once we can do anonymous structs (C11 standard) we could put a
104  * anonymous struct definition in these allocators so that the
105  * separate allocations in the kmem_cache structure of SLAB and
106  * SLUB is no longer needed.
107  */
108 #ifdef CONFIG_SLOB
109 struct kmem_cache {
110         unsigned int object_size;/* The original size of the object */
111         unsigned int size;      /* The aligned/padded/added on size  */
112         unsigned int align;     /* Alignment as calculated */
113         unsigned long flags;    /* Active flags on the slab */
114         const char *name;       /* Slab name for sysfs */
115         int refcount;           /* Use counter */
116         void (*ctor)(void *);   /* Called on object slot creation */
117         struct list_head list;  /* List of all slab caches on the system */
118 };
119 #endif
120 
121 struct mem_cgroup;
122 /*
123  * struct kmem_cache related prototypes
124  */
125 void __init kmem_cache_init(void);
126 int slab_is_available(void);
127 
128 struct kmem_cache *kmem_cache_create(const char *, size_t, size_t,
129                         unsigned long,
130                         void (*)(void *));
131 struct kmem_cache *
132 kmem_cache_create_memcg(struct mem_cgroup *, const char *, size_t, size_t,
133                         unsigned long, void (*)(void *), struct kmem_cache *);
134 void kmem_cache_destroy(struct kmem_cache *);
135 int kmem_cache_shrink(struct kmem_cache *);
136 void kmem_cache_free(struct kmem_cache *, void *);
137 
138 /*
139  * Please use this macro to create slab caches. Simply specify the
140  * name of the structure and maybe some flags that are listed above.
141  *
142  * The alignment of the struct determines object alignment. If you
143  * f.e. add ____cacheline_aligned_in_smp to the struct declaration
144  * then the objects will be properly aligned in SMP configurations.
145  */
146 #define KMEM_CACHE(__struct, __flags) kmem_cache_create(#__struct,\
147                 sizeof(struct __struct), __alignof__(struct __struct),\
148                 (__flags), NULL)
149 
150 /*
151  * The largest kmalloc size supported by the slab allocators is
152  * 32 megabyte (2^25) or the maximum allocatable page order if that is
153  * less than 32 MB.
154  *
155  * WARNING: Its not easy to increase this value since the allocators have
156  * to do various tricks to work around compiler limitations in order to
157  * ensure proper constant folding.
158  */
159 #define KMALLOC_SHIFT_HIGH      ((MAX_ORDER + PAGE_SHIFT - 1) <= 25 ? \
160                                 (MAX_ORDER + PAGE_SHIFT - 1) : 25)
161 
162 #define KMALLOC_MAX_SIZE        (1UL << KMALLOC_SHIFT_HIGH)
163 #define KMALLOC_MAX_ORDER       (KMALLOC_SHIFT_HIGH - PAGE_SHIFT)
164 
165 /*
166  * Some archs want to perform DMA into kmalloc caches and need a guaranteed
167  * alignment larger than the alignment of a 64-bit integer.
168  * Setting ARCH_KMALLOC_MINALIGN in arch headers allows that.
169  */
170 #ifdef ARCH_DMA_MINALIGN
171 #define ARCH_KMALLOC_MINALIGN ARCH_DMA_MINALIGN
172 #else
173 #define ARCH_KMALLOC_MINALIGN __alignof__(unsigned long long)
174 #endif
175 
176 /*
177  * Setting ARCH_SLAB_MINALIGN in arch headers allows a different alignment.
178  * Intended for arches that get misalignment faults even for 64 bit integer
179  * aligned buffers.
180  */
181 #ifndef ARCH_SLAB_MINALIGN
182 #define ARCH_SLAB_MINALIGN __alignof__(unsigned long long)
183 #endif
184 /*
185  * This is the main placeholder for memcg-related information in kmem caches.
186  * struct kmem_cache will hold a pointer to it, so the memory cost while
187  * disabled is 1 pointer. The runtime cost while enabled, gets bigger than it
188  * would otherwise be if that would be bundled in kmem_cache: we'll need an
189  * extra pointer chase. But the trade off clearly lays in favor of not
190  * penalizing non-users.
191  *
192  * Both the root cache and the child caches will have it. For the root cache,
193  * this will hold a dynamically allocated array large enough to hold
194  * information about the currently limited memcgs in the system.
195  *
196  * Child caches will hold extra metadata needed for its operation. Fields are:
197  *
198  * @memcg: pointer to the memcg this cache belongs to
199  * @list: list_head for the list of all caches in this memcg
200  * @root_cache: pointer to the global, root cache, this cache was derived from
201  * @dead: set to true after the memcg dies; the cache may still be around.
202  * @nr_pages: number of pages that belongs to this cache.
203  * @destroy: worker to be called whenever we are ready, or believe we may be
204  *           ready, to destroy this cache.
205  */
206 struct memcg_cache_params {
207         bool is_root_cache;
208         union {
209                 struct kmem_cache *memcg_caches[0];
210                 struct {
211                         struct mem_cgroup *memcg;
212                         struct list_head list;
213                         struct kmem_cache *root_cache;
214                         bool dead;
215                         atomic_t nr_pages;
216                         struct work_struct destroy;
217                 };
218         };
219 };
220 
221 int memcg_update_all_caches(int num_memcgs);
222 
223 struct seq_file;
224 int cache_show(struct kmem_cache *s, struct seq_file *m);
225 void print_slabinfo_header(struct seq_file *m);
226 
227 /*
228  * Common kmalloc functions provided by all allocators
229  */
230 void * __must_check __krealloc(const void *, size_t, gfp_t);
231 void * __must_check krealloc(const void *, size_t, gfp_t);
232 void kfree(const void *);
233 void kzfree(const void *);
234 size_t ksize(const void *);
235 
236 /*
237  * Allocator specific definitions. These are mainly used to establish optimized
238  * ways to convert kmalloc() calls to kmem_cache_alloc() invocations by
239  * selecting the appropriate general cache at compile time.
240  *
241  * Allocators must define at least:
242  *
243  *      kmem_cache_alloc()
244  *      __kmalloc()
245  *      kmalloc()
246  *
247  * Those wishing to support NUMA must also define:
248  *
249  *      kmem_cache_alloc_node()
250  *      kmalloc_node()
251  *
252  * See each allocator definition file for additional comments and
253  * implementation notes.
254  */
255 #ifdef CONFIG_SLUB
256 #include <linux/slub_def.h>
257 #elif defined(CONFIG_SLOB)
258 #include <linux/slob_def.h>
259 #else
260 #include <linux/slab_def.h>
261 #endif
262 
263 /**
264  * kmalloc_array - allocate memory for an array.
265  * @n: number of elements.
266  * @size: element size.
267  * @flags: the type of memory to allocate.
268  *
269  * The @flags argument may be one of:
270  *
271  * %GFP_USER - Allocate memory on behalf of user.  May sleep.
272  *
273  * %GFP_KERNEL - Allocate normal kernel ram.  May sleep.
274  *
275  * %GFP_ATOMIC - Allocation will not sleep.  May use emergency pools.
276  *   For example, use this inside interrupt handlers.
277  *
278  * %GFP_HIGHUSER - Allocate pages from high memory.
279  *
280  * %GFP_NOIO - Do not do any I/O at all while trying to get memory.
281  *
282  * %GFP_NOFS - Do not make any fs calls while trying to get memory.
283  *
284  * %GFP_NOWAIT - Allocation will not sleep.
285  *
286  * %GFP_THISNODE - Allocate node-local memory only.
287  *
288  * %GFP_DMA - Allocation suitable for DMA.
289  *   Should only be used for kmalloc() caches. Otherwise, use a
290  *   slab created with SLAB_DMA.
291  *
292  * Also it is possible to set different flags by OR'ing
293  * in one or more of the following additional @flags:
294  *
295  * %__GFP_COLD - Request cache-cold pages instead of
296  *   trying to return cache-warm pages.
297  *
298  * %__GFP_HIGH - This allocation has high priority and may use emergency pools.
299  *
300  * %__GFP_NOFAIL - Indicate that this allocation is in no way allowed to fail
301  *   (think twice before using).
302  *
303  * %__GFP_NORETRY - If memory is not immediately available,
304  *   then give up at once.
305  *
306  * %__GFP_NOWARN - If allocation fails, don't issue any warnings.
307  *
308  * %__GFP_REPEAT - If allocation fails initially, try once more before failing.
309  *
310  * There are other flags available as well, but these are not intended
311  * for general use, and so are not documented here. For a full list of
312  * potential flags, always refer to linux/gfp.h.
313  */
314 static inline void *kmalloc_array(size_t n, size_t size, gfp_t flags)
315 {
316         if (size != 0 && n > SIZE_MAX / size)
317                 return NULL;
318         return __kmalloc(n * size, flags);
319 }
320 
321 /**
322  * kcalloc - allocate memory for an array. The memory is set to zero.
323  * @n: number of elements.
324  * @size: element size.
325  * @flags: the type of memory to allocate (see kmalloc).
326  */
327 static inline void *kcalloc(size_t n, size_t size, gfp_t flags)
328 {
329         return kmalloc_array(n, size, flags | __GFP_ZERO);
330 }
331 
332 #if !defined(CONFIG_NUMA) && !defined(CONFIG_SLOB)
333 /**
334  * kmalloc_node - allocate memory from a specific node
335  * @size: how many bytes of memory are required.
336  * @flags: the type of memory to allocate (see kcalloc).
337  * @node: node to allocate from.
338  *
339  * kmalloc() for non-local nodes, used to allocate from a specific node
340  * if available. Equivalent to kmalloc() in the non-NUMA single-node
341  * case.
342  */
343 static inline void *kmalloc_node(size_t size, gfp_t flags, int node)
344 {
345         return kmalloc(size, flags);
346 }
347 
348 static inline void *__kmalloc_node(size_t size, gfp_t flags, int node)
349 {
350         return __kmalloc(size, flags);
351 }
352 
353 void *kmem_cache_alloc(struct kmem_cache *, gfp_t);
354 
355 static inline void *kmem_cache_alloc_node(struct kmem_cache *cachep,
356                                         gfp_t flags, int node)
357 {
358         return kmem_cache_alloc(cachep, flags);
359 }
360 #endif /* !CONFIG_NUMA && !CONFIG_SLOB */
361 
362 /*
363  * kmalloc_track_caller is a special version of kmalloc that records the
364  * calling function of the routine calling it for slab leak tracking instead
365  * of just the calling function (confusing, eh?).
366  * It's useful when the call to kmalloc comes from a widely-used standard
367  * allocator where we care about the real place the memory allocation
368  * request comes from.
369  */
370 #if defined(CONFIG_DEBUG_SLAB) || defined(CONFIG_SLUB) || \
371         (defined(CONFIG_SLAB) && defined(CONFIG_TRACING)) || \
372         (defined(CONFIG_SLOB) && defined(CONFIG_TRACING))
373 extern void *__kmalloc_track_caller(size_t, gfp_t, unsigned long);
374 #define kmalloc_track_caller(size, flags) \
375         __kmalloc_track_caller(size, flags, _RET_IP_)
376 #else
377 #define kmalloc_track_caller(size, flags) \
378         __kmalloc(size, flags)
379 #endif /* DEBUG_SLAB */
380 
381 #ifdef CONFIG_NUMA
382 /*
383  * kmalloc_node_track_caller is a special version of kmalloc_node that
384  * records the calling function of the routine calling it for slab leak
385  * tracking instead of just the calling function (confusing, eh?).
386  * It's useful when the call to kmalloc_node comes from a widely-used
387  * standard allocator where we care about the real place the memory
388  * allocation request comes from.
389  */
390 #if defined(CONFIG_DEBUG_SLAB) || defined(CONFIG_SLUB) || \
391         (defined(CONFIG_SLAB) && defined(CONFIG_TRACING)) || \
392         (defined(CONFIG_SLOB) && defined(CONFIG_TRACING))
393 extern void *__kmalloc_node_track_caller(size_t, gfp_t, int, unsigned long);
394 #define kmalloc_node_track_caller(size, flags, node) \
395         __kmalloc_node_track_caller(size, flags, node, \
396                         _RET_IP_)
397 #else
398 #define kmalloc_node_track_caller(size, flags, node) \
399         __kmalloc_node(size, flags, node)
400 #endif
401 
402 #else /* CONFIG_NUMA */
403 
404 #define kmalloc_node_track_caller(size, flags, node) \
405         kmalloc_track_caller(size, flags)
406 
407 #endif /* CONFIG_NUMA */
408 
409 /*
410  * Shortcuts
411  */
412 static inline void *kmem_cache_zalloc(struct kmem_cache *k, gfp_t flags)
413 {
414         return kmem_cache_alloc(k, flags | __GFP_ZERO);
415 }
416 
417 /**
418  * kzalloc - allocate memory. The memory is set to zero.
419  * @size: how many bytes of memory are required.
420  * @flags: the type of memory to allocate (see kmalloc).
421  */
422 static inline void *kzalloc(size_t size, gfp_t flags)
423 {
424         return kmalloc(size, flags | __GFP_ZERO);
425 }
426 
427 /**
428  * kzalloc_node - allocate zeroed memory from a particular memory node.
429  * @size: how many bytes of memory are required.
430  * @flags: the type of memory to allocate (see kmalloc).
431  * @node: memory node from which to allocate
432  */
433 static inline void *kzalloc_node(size_t size, gfp_t flags, int node)
434 {
435         return kmalloc_node(size, flags | __GFP_ZERO, node);
436 }
437 
438 /*
439  * Determine the size of a slab object
440  */
441 static inline unsigned int kmem_cache_size(struct kmem_cache *s)
442 {
443         return s->object_size;
444 }
445 
446 void __init kmem_cache_init_late(void);
447 
448 #endif  /* _LINUX_SLAB_H */
449 

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