include/linux/slab.h - kernel/msm - Gitiles

 /*
  * Written by Mark Hemment, 1996 (markhe@nextd.demon.co.uk).
  *
  * (C) SGI 2006, Christoph Lameter
  * 	Cleaned up and restructured to ease the addition of alternative
  * 	implementations of SLAB allocators.
  */

 #ifndef _LINUX_SLAB_H
 #define	_LINUX_SLAB_H

 #include <linux/gfp.h>
 #include <linux/types.h>

 /*
  * Flags to pass to kmem_cache_create().
  * The ones marked DEBUG are only valid if CONFIG_SLAB_DEBUG is set.
  */
 #define SLAB_DEBUG_FREE		0x00000100UL	/* DEBUG: Perform (expensive) checks on free */
 #define SLAB_RED_ZONE		0x00000400UL	/* DEBUG: Red zone objs in a cache */
 #define SLAB_POISON		0x00000800UL	/* DEBUG: Poison objects */
 #define SLAB_HWCACHE_ALIGN	0x00002000UL	/* Align objs on cache lines */
 #define SLAB_CACHE_DMA		0x00004000UL	/* Use GFP_DMA memory */
 #define SLAB_STORE_USER		0x00010000UL	/* DEBUG: Store the last owner for bug hunting */
 #define SLAB_PANIC		0x00040000UL	/* Panic if kmem_cache_create() fails */
 /*
  * SLAB_DESTROY_BY_RCU - **WARNING** READ THIS!
  *
  * This delays freeing the SLAB page by a grace period, it does _NOT_
  * delay object freeing. This means that if you do kmem_cache_free()
  * that memory location is free to be reused at any time. Thus it may
  * be possible to see another object there in the same RCU grace period.
  *
  * This feature only ensures the memory location backing the object
  * stays valid, the trick to using this is relying on an independent
  * object validation pass. Something like:
  *
  *  rcu_read_lock()
  * again:
  *  obj = lockless_lookup(key);
  *  if (obj) {
  *    if (!try_get_ref(obj)) // might fail for free objects
  *      goto again;
  *
  *    if (obj->key != key) { // not the object we expected
  *      put_ref(obj);
  *      goto again;
  *    }
  *  }
  *  rcu_read_unlock();
  *
  * See also the comment on struct slab_rcu in mm/slab.c.
  */
 #define SLAB_DESTROY_BY_RCU	0x00080000UL	/* Defer freeing slabs to RCU */
 #define SLAB_MEM_SPREAD		0x00100000UL	/* Spread some memory over cpuset */
 #define SLAB_TRACE		0x00200000UL	/* Trace allocations and frees */

 /* Flag to prevent checks on free */
 #ifdef CONFIG_DEBUG_OBJECTS
 # define SLAB_DEBUG_OBJECTS	0x00400000UL
 #else
 # define SLAB_DEBUG_OBJECTS	0x00000000UL
 #endif

 /* The following flags affect the page allocator grouping pages by mobility */
 #define SLAB_RECLAIM_ACCOUNT	0x00020000UL		/* Objects are reclaimable */
 #define SLAB_TEMPORARY		SLAB_RECLAIM_ACCOUNT	/* Objects are short-lived */
 /*
  * ZERO_SIZE_PTR will be returned for zero sized kmalloc requests.
  *
  * Dereferencing ZERO_SIZE_PTR will lead to a distinct access fault.
  *
  * ZERO_SIZE_PTR can be passed to kfree though in the same way that NULL can.
  * Both make kfree a no-op.
  */
 #define ZERO_SIZE_PTR ((void *)16)

 #define ZERO_OR_NULL_PTR(x) ((unsigned long)(x) <= \
 				(unsigned long)ZERO_SIZE_PTR)

 /*
  * struct kmem_cache related prototypes
  */
 void __init kmem_cache_init(void);
 int slab_is_available(void);

 struct kmem_cache *kmem_cache_create(const char *, size_t, size_t,
 			unsigned long,
 			void (*)(void *));
 void kmem_cache_destroy(struct kmem_cache *);
 int kmem_cache_shrink(struct kmem_cache *);
 void kmem_cache_free(struct kmem_cache *, void *);
 unsigned int kmem_cache_size(struct kmem_cache *);
 const char *kmem_cache_name(struct kmem_cache *);
 int kmem_ptr_validate(struct kmem_cache *cachep, const void *ptr);

 /*
  * Please use this macro to create slab caches. Simply specify the
  * name of the structure and maybe some flags that are listed above.
  *
  * The alignment of the struct determines object alignment. If you
  * f.e. add ____cacheline_aligned_in_smp to the struct declaration
  * then the objects will be properly aligned in SMP configurations.
  */
 #define KMEM_CACHE(__struct, __flags) kmem_cache_create(#__struct,\
 		sizeof(struct __struct), __alignof__(struct __struct),\
 		(__flags), NULL)

 /*
  * The largest kmalloc size supported by the slab allocators is
  * 32 megabyte (2^25) or the maximum allocatable page order if that is
  * less than 32 MB.
  *
  * WARNING: Its not easy to increase this value since the allocators have
  * to do various tricks to work around compiler limitations in order to
  * ensure proper constant folding.
  */
 #define KMALLOC_SHIFT_HIGH	((MAX_ORDER + PAGE_SHIFT - 1) <= 25 ? \
 				(MAX_ORDER + PAGE_SHIFT - 1) : 25)

 #define KMALLOC_MAX_SIZE	(1UL << KMALLOC_SHIFT_HIGH)
 #define KMALLOC_MAX_ORDER	(KMALLOC_SHIFT_HIGH - PAGE_SHIFT)

 /*
  * Common kmalloc functions provided by all allocators
  */
 void * __must_check __krealloc(const void *, size_t, gfp_t);
 void * __must_check krealloc(const void *, size_t, gfp_t);
 void kfree(const void *);
 void kzfree(const void *);
 size_t ksize(const void *);

 /*
  * Allocator specific definitions. These are mainly used to establish optimized
  * ways to convert kmalloc() calls to kmem_cache_alloc() invocations by
  * selecting the appropriate general cache at compile time.
  *
  * Allocators must define at least:
  *
  *	kmem_cache_alloc()
  *	__kmalloc()
  *	kmalloc()
  *
  * Those wishing to support NUMA must also define:
  *
  *	kmem_cache_alloc_node()
  *	kmalloc_node()
  *
  * See each allocator definition file for additional comments and
  * implementation notes.
  */
 #ifdef CONFIG_SLUB
 #include <linux/slub_def.h>
 #elif defined(CONFIG_SLOB)
 #include <linux/slob_def.h>
 #else
 #include <linux/slab_def.h>
 #endif

 /**
  * kcalloc - allocate memory for an array. The memory is set to zero.
  * @n: number of elements.
  * @size: element size.
  * @flags: the type of memory to allocate.
  *
  * The @flags argument may be one of:
  *
  * %GFP_USER - Allocate memory on behalf of user.  May sleep.
  *
  * %GFP_KERNEL - Allocate normal kernel ram.  May sleep.
  *
  * %GFP_ATOMIC - Allocation will not sleep.  May use emergency pools.
  *   For example, use this inside interrupt handlers.
  *
  * %GFP_HIGHUSER - Allocate pages from high memory.
  *
  * %GFP_NOIO - Do not do any I/O at all while trying to get memory.
  *
  * %GFP_NOFS - Do not make any fs calls while trying to get memory.
  *
  * %GFP_NOWAIT - Allocation will not sleep.
  *
  * %GFP_THISNODE - Allocate node-local memory only.
  *
  * %GFP_DMA - Allocation suitable for DMA.
  *   Should only be used for kmalloc() caches. Otherwise, use a
  *   slab created with SLAB_DMA.
  *
  * Also it is possible to set different flags by OR'ing
  * in one or more of the following additional @flags:
  *
  * %__GFP_COLD - Request cache-cold pages instead of
  *   trying to return cache-warm pages.
  *
  * %__GFP_HIGH - This allocation has high priority and may use emergency pools.
  *
  * %__GFP_NOFAIL - Indicate that this allocation is in no way allowed to fail
  *   (think twice before using).
  *
  * %__GFP_NORETRY - If memory is not immediately available,
  *   then give up at once.
  *
  * %__GFP_NOWARN - If allocation fails, don't issue any warnings.
  *
  * %__GFP_REPEAT - If allocation fails initially, try once more before failing.
  *
  * There are other flags available as well, but these are not intended
  * for general use, and so are not documented here. For a full list of
  * potential flags, always refer to linux/gfp.h.
  */
 static inline void *kcalloc(size_t n, size_t size, gfp_t flags)
 {
 	if (size != 0 && n > ULONG_MAX / size)
 		return NULL;
 	return __kmalloc(n * size, flags | __GFP_ZERO);
 }

 #if !defined(CONFIG_NUMA) && !defined(CONFIG_SLOB)
 /**
  * kmalloc_node - allocate memory from a specific node
  * @size: how many bytes of memory are required.
  * @flags: the type of memory to allocate (see kcalloc).
  * @node: node to allocate from.
  *
  * kmalloc() for non-local nodes, used to allocate from a specific node
  * if available. Equivalent to kmalloc() in the non-NUMA single-node
  * case.
  */
 static inline void *kmalloc_node(size_t size, gfp_t flags, int node)
 {
 	return kmalloc(size, flags);
 }

 static inline void *__kmalloc_node(size_t size, gfp_t flags, int node)
 {
 	return __kmalloc(size, flags);
 }

 void *kmem_cache_alloc(struct kmem_cache *, gfp_t);

 static inline void *kmem_cache_alloc_node(struct kmem_cache *cachep,
 					gfp_t flags, int node)
 {
 	return kmem_cache_alloc(cachep, flags);
 }
 #endif /* !CONFIG_NUMA && !CONFIG_SLOB */

 /*
  * kmalloc_track_caller is a special version of kmalloc that records the
  * calling function of the routine calling it for slab leak tracking instead
  * of just the calling function (confusing, eh?).
  * It's useful when the call to kmalloc comes from a widely-used standard
  * allocator where we care about the real place the memory allocation
  * request comes from.
  */
 #if defined(CONFIG_DEBUG_SLAB) || defined(CONFIG_SLUB)
 extern void *__kmalloc_track_caller(size_t, gfp_t, unsigned long);
 #define kmalloc_track_caller(size, flags) \
 	__kmalloc_track_caller(size, flags, _RET_IP_)
 #else
 #define kmalloc_track_caller(size, flags) \
 	__kmalloc(size, flags)
 #endif /* DEBUG_SLAB */

 #ifdef CONFIG_NUMA
 /*
  * kmalloc_node_track_caller is a special version of kmalloc_node that
  * records the calling function of the routine calling it for slab leak
  * tracking instead of just the calling function (confusing, eh?).
  * It's useful when the call to kmalloc_node comes from a widely-used
  * standard allocator where we care about the real place the memory
  * allocation request comes from.
  */
 #if defined(CONFIG_DEBUG_SLAB) || defined(CONFIG_SLUB)
 extern void *__kmalloc_node_track_caller(size_t, gfp_t, int, unsigned long);
 #define kmalloc_node_track_caller(size, flags, node) \
 	__kmalloc_node_track_caller(size, flags, node, \
 			_RET_IP_)
 #else
 #define kmalloc_node_track_caller(size, flags, node) \
 	__kmalloc_node(size, flags, node)
 #endif

 #else /* CONFIG_NUMA */

 #define kmalloc_node_track_caller(size, flags, node) \
 	kmalloc_track_caller(size, flags)

 #endif /* CONFIG_NUMA */

 /*
  * Shortcuts
  */
 static inline void *kmem_cache_zalloc(struct kmem_cache *k, gfp_t flags)
 {
 	return kmem_cache_alloc(k, flags | __GFP_ZERO);
 }

 /**
  * kzalloc - allocate memory. The memory is set to zero.
  * @size: how many bytes of memory are required.
  * @flags: the type of memory to allocate (see kmalloc).
  */
 static inline void *kzalloc(size_t size, gfp_t flags)
 {
 	return kmalloc(size, flags | __GFP_ZERO);
 }

 /**
  * kzalloc_node - allocate zeroed memory from a particular memory node.
  * @size: how many bytes of memory are required.
  * @flags: the type of memory to allocate (see kmalloc).
  * @node: memory node from which to allocate
  */
 static inline void *kzalloc_node(size_t size, gfp_t flags, int node)
 {
 	return kmalloc_node(size, flags | __GFP_ZERO, node);
 }

 #endif	/* _LINUX_SLAB_H */
	/*
	* Written by Mark Hemment, 1996 (markhe@nextd.demon.co.uk).
	*
	* (C) SGI 2006, Christoph Lameter
	* Cleaned up and restructured to ease the addition of alternative
	* implementations of SLAB allocators.
	*/

	#ifndef _LINUX_SLAB_H
	#define _LINUX_SLAB_H

	#include <linux/gfp.h>
	#include <linux/types.h>

	/*
	* Flags to pass to kmem_cache_create().
	* The ones marked DEBUG are only valid if CONFIG_SLAB_DEBUG is set.
	*/
	#define SLAB_DEBUG_FREE 0x00000100UL /* DEBUG: Perform (expensive) checks on free */
	#define SLAB_RED_ZONE 0x00000400UL /* DEBUG: Red zone objs in a cache */
	#define SLAB_POISON 0x00000800UL /* DEBUG: Poison objects */
	#define SLAB_HWCACHE_ALIGN 0x00002000UL /* Align objs on cache lines */
	#define SLAB_CACHE_DMA 0x00004000UL /* Use GFP_DMA memory */
	#define SLAB_STORE_USER 0x00010000UL /* DEBUG: Store the last owner for bug hunting */
	#define SLAB_PANIC 0x00040000UL /* Panic if kmem_cache_create() fails */
	/*
	* SLAB_DESTROY_BY_RCU - WARNING READ THIS!
	*
	* This delays freeing the SLAB page by a grace period, it does _NOT_
	* delay object freeing. This means that if you do kmem_cache_free()
	* that memory location is free to be reused at any time. Thus it may
	* be possible to see another object there in the same RCU grace period.
	*
	* This feature only ensures the memory location backing the object
	* stays valid, the trick to using this is relying on an independent
	* object validation pass. Something like:
	*
	* rcu_read_lock()
	* again:
	* obj = lockless_lookup(key);
	* if (obj) {
	* if (!try_get_ref(obj)) // might fail for free objects
	* goto again;
	*
	* if (obj->key != key) { // not the object we expected
	* put_ref(obj);
	* goto again;
	* }
	* }
	* rcu_read_unlock();
	*
	* See also the comment on struct slab_rcu in mm/slab.c.
	*/
	#define SLAB_DESTROY_BY_RCU 0x00080000UL /* Defer freeing slabs to RCU */
	#define SLAB_MEM_SPREAD 0x00100000UL /* Spread some memory over cpuset */
	#define SLAB_TRACE 0x00200000UL /* Trace allocations and frees */

	/* Flag to prevent checks on free */
	#ifdef CONFIG_DEBUG_OBJECTS
	# define SLAB_DEBUG_OBJECTS 0x00400000UL
	#else
	# define SLAB_DEBUG_OBJECTS 0x00000000UL
	#endif

	/* The following flags affect the page allocator grouping pages by mobility */
	#define SLAB_RECLAIM_ACCOUNT 0x00020000UL /* Objects are reclaimable */
	#define SLAB_TEMPORARY SLAB_RECLAIM_ACCOUNT /* Objects are short-lived */
	/*
	* ZERO_SIZE_PTR will be returned for zero sized kmalloc requests.
	*
	* Dereferencing ZERO_SIZE_PTR will lead to a distinct access fault.
	*
	* ZERO_SIZE_PTR can be passed to kfree though in the same way that NULL can.
	* Both make kfree a no-op.
	*/
	#define ZERO_SIZE_PTR ((void *)16)

	#define ZERO_OR_NULL_PTR(x) ((unsigned long)(x) <= \
	(unsigned long)ZERO_SIZE_PTR)

	/*
	* struct kmem_cache related prototypes
	*/
	void __init kmem_cache_init(void);
	int slab_is_available(void);

	struct kmem_cache kmem_cache_create(const char , size_t, size_t,
	unsigned long,
	void ()(void ));
	void kmem_cache_destroy(struct kmem_cache *);
	int kmem_cache_shrink(struct kmem_cache *);
	void kmem_cache_free(struct kmem_cache , void );
	unsigned int kmem_cache_size(struct kmem_cache *);
	const char kmem_cache_name(struct kmem_cache );
	int kmem_ptr_validate(struct kmem_cache cachep, const void ptr);

	/*
	* Please use this macro to create slab caches. Simply specify the
	* name of the structure and maybe some flags that are listed above.
	*
	* The alignment of the struct determines object alignment. If you
	* f.e. add ____cacheline_aligned_in_smp to the struct declaration
	* then the objects will be properly aligned in SMP configurations.
	*/
	#define KMEM_CACHE(__struct, __flags) kmem_cache_create(#__struct,\
	sizeof(struct __struct), __alignof__(struct __struct),\
	(__flags), NULL)

	/*
	* The largest kmalloc size supported by the slab allocators is
	* 32 megabyte (2^25) or the maximum allocatable page order if that is
	* less than 32 MB.
	*
	* WARNING: Its not easy to increase this value since the allocators have
	* to do various tricks to work around compiler limitations in order to
	* ensure proper constant folding.
	*/
	#define KMALLOC_SHIFT_HIGH ((MAX_ORDER + PAGE_SHIFT - 1) <= 25 ? \
	(MAX_ORDER + PAGE_SHIFT - 1) : 25)

	#define KMALLOC_MAX_SIZE (1UL << KMALLOC_SHIFT_HIGH)
	#define KMALLOC_MAX_ORDER (KMALLOC_SHIFT_HIGH - PAGE_SHIFT)

	/*
	* Common kmalloc functions provided by all allocators
	*/
	void * __must_check __krealloc(const void *, size_t, gfp_t);
	void * __must_check krealloc(const void *, size_t, gfp_t);
	void kfree(const void *);
	void kzfree(const void *);
	size_t ksize(const void *);

	/*
	* Allocator specific definitions. These are mainly used to establish optimized
	* ways to convert kmalloc() calls to kmem_cache_alloc() invocations by
	* selecting the appropriate general cache at compile time.
	*
	* Allocators must define at least:
	*
	* kmem_cache_alloc()
	* __kmalloc()
	* kmalloc()
	*
	* Those wishing to support NUMA must also define:
	*
	* kmem_cache_alloc_node()
	* kmalloc_node()
	*
	* See each allocator definition file for additional comments and
	* implementation notes.
	*/
	#ifdef CONFIG_SLUB
	#include <linux/slub_def.h>
	#elif defined(CONFIG_SLOB)
	#include <linux/slob_def.h>
	#else
	#include <linux/slab_def.h>
	#endif

	/**
	* kcalloc - allocate memory for an array. The memory is set to zero.
	* @n: number of elements.
	* @size: element size.
	* @flags: the type of memory to allocate.
	*
	* The @flags argument may be one of:
	*
	* %GFP_USER - Allocate memory on behalf of user. May sleep.
	*
	* %GFP_KERNEL - Allocate normal kernel ram. May sleep.
	*
	* %GFP_ATOMIC - Allocation will not sleep. May use emergency pools.
	* For example, use this inside interrupt handlers.
	*
	* %GFP_HIGHUSER - Allocate pages from high memory.
	*
	* %GFP_NOIO - Do not do any I/O at all while trying to get memory.
	*
	* %GFP_NOFS - Do not make any fs calls while trying to get memory.
	*
	* %GFP_NOWAIT - Allocation will not sleep.
	*
	* %GFP_THISNODE - Allocate node-local memory only.
	*
	* %GFP_DMA - Allocation suitable for DMA.
	* Should only be used for kmalloc() caches. Otherwise, use a
	* slab created with SLAB_DMA.
	*
	* Also it is possible to set different flags by OR'ing
	* in one or more of the following additional @flags:
	*
	* %__GFP_COLD - Request cache-cold pages instead of
	* trying to return cache-warm pages.
	*
	* %__GFP_HIGH - This allocation has high priority and may use emergency pools.
	*
	* %__GFP_NOFAIL - Indicate that this allocation is in no way allowed to fail
	* (think twice before using).
	*
	* %__GFP_NORETRY - If memory is not immediately available,
	* then give up at once.
	*
	* %__GFP_NOWARN - If allocation fails, don't issue any warnings.
	*
	* %__GFP_REPEAT - If allocation fails initially, try once more before failing.
	*
	* There are other flags available as well, but these are not intended
	* for general use, and so are not documented here. For a full list of
	* potential flags, always refer to linux/gfp.h.
	*/
	static inline void *kcalloc(size_t n, size_t size, gfp_t flags)
	{
	if (size != 0 && n > ULONG_MAX / size)
	return NULL;
	return __kmalloc(n * size, flags \| __GFP_ZERO);
	}

	#if !defined(CONFIG_NUMA) && !defined(CONFIG_SLOB)
	/**
	* kmalloc_node - allocate memory from a specific node
	* @size: how many bytes of memory are required.
	* @flags: the type of memory to allocate (see kcalloc).
	* @node: node to allocate from.
	*
	* kmalloc() for non-local nodes, used to allocate from a specific node
	* if available. Equivalent to kmalloc() in the non-NUMA single-node
	* case.
	*/
	static inline void *kmalloc_node(size_t size, gfp_t flags, int node)
	{
	return kmalloc(size, flags);
	}

	static inline void *__kmalloc_node(size_t size, gfp_t flags, int node)
	{
	return __kmalloc(size, flags);
	}

	void kmem_cache_alloc(struct kmem_cache , gfp_t);

	static inline void kmem_cache_alloc_node(struct kmem_cache cachep,
	gfp_t flags, int node)
	{
	return kmem_cache_alloc(cachep, flags);
	}
	#endif /* !CONFIG_NUMA && !CONFIG_SLOB */

	/*
	* kmalloc_track_caller is a special version of kmalloc that records the
	* calling function of the routine calling it for slab leak tracking instead
	* of just the calling function (confusing, eh?).
	* It's useful when the call to kmalloc comes from a widely-used standard
	* allocator where we care about the real place the memory allocation
	* request comes from.
	*/
	#if defined(CONFIG_DEBUG_SLAB) \|\| defined(CONFIG_SLUB)
	extern void *__kmalloc_track_caller(size_t, gfp_t, unsigned long);
	#define kmalloc_track_caller(size, flags) \
	__kmalloc_track_caller(size, flags, _RET_IP_)
	#else
	#define kmalloc_track_caller(size, flags) \
	__kmalloc(size, flags)
	#endif /* DEBUG_SLAB */

	#ifdef CONFIG_NUMA
	/*
	* kmalloc_node_track_caller is a special version of kmalloc_node that
	* records the calling function of the routine calling it for slab leak
	* tracking instead of just the calling function (confusing, eh?).
	* It's useful when the call to kmalloc_node comes from a widely-used
	* standard allocator where we care about the real place the memory
	* allocation request comes from.
	*/
	#if defined(CONFIG_DEBUG_SLAB) \|\| defined(CONFIG_SLUB)
	extern void *__kmalloc_node_track_caller(size_t, gfp_t, int, unsigned long);
	#define kmalloc_node_track_caller(size, flags, node) \
	__kmalloc_node_track_caller(size, flags, node, \
	_RET_IP_)
	#else
	#define kmalloc_node_track_caller(size, flags, node) \
	__kmalloc_node(size, flags, node)
	#endif

	#else /* CONFIG_NUMA */

	#define kmalloc_node_track_caller(size, flags, node) \
	kmalloc_track_caller(size, flags)

	#endif /* CONFIG_NUMA */

	/*
	* Shortcuts
	*/
	static inline void kmem_cache_zalloc(struct kmem_cache k, gfp_t flags)
	{
	return kmem_cache_alloc(k, flags \| __GFP_ZERO);
	}

	/**
	* kzalloc - allocate memory. The memory is set to zero.
	* @size: how many bytes of memory are required.
	* @flags: the type of memory to allocate (see kmalloc).
	*/
	static inline void *kzalloc(size_t size, gfp_t flags)
	{
	return kmalloc(size, flags \| __GFP_ZERO);
	}

	/**
	* kzalloc_node - allocate zeroed memory from a particular memory node.
	* @size: how many bytes of memory are required.
	* @flags: the type of memory to allocate (see kmalloc).
	* @node: memory node from which to allocate
	*/
	static inline void *kzalloc_node(size_t size, gfp_t flags, int node)
	{
	return kmalloc_node(size, flags \| __GFP_ZERO, node);
	}

	#endif /* _LINUX_SLAB_H */