slub_def.h

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#ifndef _LINUX_SLUB_DEF_H
#define _LINUX_SLUB_DEF_H

/*
 * SLUB : A Slab allocator without object queues.
 *
 * (C) 2007 SGI, Christoph Lameter
 */
#include <linux/types.h>
#include <linux/gfp.h>
#include <linux/bug.h>
#include <linux/workqueue.h>
#include <linux/kobject.h>

#include <linux/kmemleak.h>

enum stat_item {
    ALLOC_FASTPATH,     /* Allocation from cpu slab */
    ALLOC_SLOWPATH,     /* Allocation by getting a new cpu slab */
    FREE_FASTPATH,      /* Free to cpu slub */
    FREE_SLOWPATH,      /* Freeing not to cpu slab */
    FREE_FROZEN,        /* Freeing to frozen slab */
    FREE_ADD_PARTIAL,   /* Freeing moves slab to partial list */
    FREE_REMOVE_PARTIAL,    /* Freeing removes last object */
    ALLOC_FROM_PARTIAL, /* Cpu slab acquired from node partial list */
    ALLOC_SLAB,     /* Cpu slab acquired from page allocator */
    ALLOC_REFILL,       /* Refill cpu slab from slab freelist */
    ALLOC_NODE_MISMATCH,    /* Switching cpu slab */
    FREE_SLAB,      /* Slab freed to the page allocator */
    CPUSLAB_FLUSH,      /* Abandoning of the cpu slab */
    DEACTIVATE_FULL,    /* Cpu slab was full when deactivated */
    DEACTIVATE_EMPTY,   /* Cpu slab was empty when deactivated */
    DEACTIVATE_TO_HEAD, /* Cpu slab was moved to the head of partials */
    DEACTIVATE_TO_TAIL, /* Cpu slab was moved to the tail of partials */
    DEACTIVATE_REMOTE_FREES,/* Slab contained remotely freed objects */
    DEACTIVATE_BYPASS,  /* Implicit deactivation */
    ORDER_FALLBACK,     /* Number of times fallback was necessary */
    CMPXCHG_DOUBLE_CPU_FAIL,/* Failure of this_cpu_cmpxchg_double */
    CMPXCHG_DOUBLE_FAIL,    /* Number of times that cmpxchg double did not match */
    CPU_PARTIAL_ALLOC,  /* Used cpu partial on alloc */
    CPU_PARTIAL_FREE,   /* Refill cpu partial on free */
    CPU_PARTIAL_NODE,   /* Refill cpu partial from node partial */
    CPU_PARTIAL_DRAIN,  /* Drain cpu partial to node partial */
    NR_SLUB_STAT_ITEMS };

struct kmem_cache_cpu {
    void **freelist;    /* Pointer to next available object */
    unsigned long tid;  /* Globally unique transaction id */
    struct page *page;  /* The slab from which we are allocating */
    struct page *partial;   /* Partially allocated frozen slabs */
#ifdef CONFIG_SLUB_STATS
    unsigned stat[NR_SLUB_STAT_ITEMS];
#endif
};

struct kmem_cache_node {
    spinlock_t list_lock;   /* Protect partial list and nr_partial */
    unsigned long nr_partial;
    struct list_head partial;
#ifdef CONFIG_SLUB_DEBUG
    atomic_long_t nr_slabs;
    atomic_long_t total_objects;
    struct list_head full;
#endif
};

/*
 * Word size structure that can be atomically updated or read and that
 * contains both the order and the number of objects that a slab of the
 * given order would contain.
 */
struct kmem_cache_order_objects {
    unsigned long x;
};

/*
 * Slab cache management.
 */
struct kmem_cache {
    struct kmem_cache_cpu __percpu *cpu_slab;
    /* Used for retriving partial slabs etc */
    unsigned long flags;
    unsigned long min_partial;
    int size;       /* The size of an object including meta data */
    int object_size;    /* The size of an object without meta data */
    int offset;     /* Free pointer offset. */
    int cpu_partial;    /* Number of per cpu partial objects to keep around */
    struct kmem_cache_order_objects oo;

    /* Allocation and freeing of slabs */
    struct kmem_cache_order_objects max;
    struct kmem_cache_order_objects min;
    gfp_t allocflags;   /* gfp flags to use on each alloc */
    int refcount;       /* Refcount for slab cache destroy */
    void (*ctor)(void *);
    int inuse;      /* Offset to metadata */
    int align;      /* Alignment */
    int reserved;       /* Reserved bytes at the end of slabs */
    const char *name;   /* Name (only for display!) */
    struct list_head list;  /* List of slab caches */
#ifdef CONFIG_SYSFS
    struct kobject kobj;    /* For sysfs */
#endif

#ifdef CONFIG_NUMA
    /*
     * Defragmentation by allocating from a remote node.
     */
    int remote_node_defrag_ratio;
#endif
    struct kmem_cache_node *node[MAX_NUMNODES];
};

/*
 * Kmalloc subsystem.
 */
#if defined(ARCH_DMA_MINALIGN) && ARCH_DMA_MINALIGN > 8
#define KMALLOC_MIN_SIZE ARCH_DMA_MINALIGN
#else
#define KMALLOC_MIN_SIZE 8
#endif

#define KMALLOC_SHIFT_LOW ilog2(KMALLOC_MIN_SIZE)

/*
 * Maximum kmalloc object size handled by SLUB. Larger object allocations
 * are passed through to the page allocator. The page allocator "fastpath"
 * is relatively slow so we need this value sufficiently high so that
 * performance critical objects are allocated through the SLUB fastpath.
 *
 * This should be dropped to PAGE_SIZE / 2 once the page allocator
 * "fastpath" becomes competitive with the slab allocator fastpaths.
 */
#define SLUB_MAX_SIZE (2 * PAGE_SIZE)

#define SLUB_PAGE_SHIFT (PAGE_SHIFT + 2)

#ifdef CONFIG_ZONE_DMA
#define SLUB_DMA __GFP_DMA
#else
/* Disable DMA functionality */
#define SLUB_DMA (__force gfp_t)0
#endif

/*
 * We keep the general caches in an array of slab caches that are used for
 * 2^x bytes of allocations.
 */
extern struct kmem_cache *kmalloc_caches[SLUB_PAGE_SHIFT];

/*
 * Sorry that the following has to be that ugly but some versions of GCC
 * have trouble with constant propagation and loops.
 */
static __always_inline int kmalloc_index(size_t size)
{
    if (!size)
        return 0;

    if (size <= KMALLOC_MIN_SIZE)
        return KMALLOC_SHIFT_LOW;

    if (KMALLOC_MIN_SIZE <= 32 && size > 64 && size <= 96)
        return 1;
    if (KMALLOC_MIN_SIZE <= 64 && size > 128 && size <= 192)
        return 2;
    if (size <=          8) return 3;
    if (size <=         16) return 4;
    if (size <=         32) return 5;
    if (size <=         64) return 6;
    if (size <=        128) return 7;
    if (size <=        256) return 8;
    if (size <=        512) return 9;
    if (size <=       1024) return 10;
    if (size <=   2 * 1024) return 11;
    if (size <=   4 * 1024) return 12;
/*
 * The following is only needed to support architectures with a larger page
 * size than 4k. We need to support 2 * PAGE_SIZE here. So for a 64k page
 * size we would have to go up to 128k.
 */
    if (size <=   8 * 1024) return 13;
    if (size <=  16 * 1024) return 14;
    if (size <=  32 * 1024) return 15;
    if (size <=  64 * 1024) return 16;
    if (size <= 128 * 1024) return 17;
    if (size <= 256 * 1024) return 18;
    if (size <= 512 * 1024) return 19;
    if (size <= 1024 * 1024) return 20;
    if (size <=  2 * 1024 * 1024) return 21;
    BUG();
    return -1; /* Will never be reached */

/*
 * What we really wanted to do and cannot do because of compiler issues is:
 *  int i;
 *  for (i = KMALLOC_SHIFT_LOW; i <= KMALLOC_SHIFT_HIGH; i++)
 *      if (size <= (1 << i))
 *          return i;
 */
}

/*
 * Find the slab cache for a given combination of allocation flags and size.
 *
 * This ought to end up with a global pointer to the right cache
 * in kmalloc_caches.
 */
static __always_inline struct kmem_cache *kmalloc_slab(size_t size)
{
    int index = kmalloc_index(size);

    if (index == 0)
        return NULL;

    return kmalloc_caches[index];
}

void *kmem_cache_alloc(struct kmem_cache *, gfp_t);
void *__kmalloc(size_t size, gfp_t flags);

static __always_inline void *
kmalloc_order(size_t size, gfp_t flags, unsigned int order)
{
    void *ret = (void *) __get_free_pages(flags | __GFP_COMP, order);
    kmemleak_alloc(ret, size, 1, flags);
    return ret;
}

#ifdef CONFIG_SLUB_DEBUG
extern bool verify_mem_not_deleted(const void *x);
#else
static inline bool verify_mem_not_deleted(const void *x)
{
    return true;
}
#endif

#ifdef CONFIG_TRACING
extern void *
kmem_cache_alloc_trace(struct kmem_cache *s, gfp_t gfpflags, size_t size);
extern void *kmalloc_order_trace(size_t size, gfp_t flags, unsigned int order);
#else
static __always_inline void *
kmem_cache_alloc_trace(struct kmem_cache *s, gfp_t gfpflags, size_t size)
{
    return kmem_cache_alloc(s, gfpflags);
}

static __always_inline void *
kmalloc_order_trace(size_t size, gfp_t flags, unsigned int order)
{
    return kmalloc_order(size, flags, order);
}
#endif

static __always_inline void *kmalloc_large(size_t size, gfp_t flags)
{
    unsigned int order = get_order(size);
    return kmalloc_order_trace(size, flags, order);
}

static __always_inline void *kmalloc(size_t size, gfp_t flags)
{
    if (__builtin_constant_p(size)) {
        if (size > SLUB_MAX_SIZE)
            return kmalloc_large(size, flags);

        if (!(flags & SLUB_DMA)) {
            struct kmem_cache *s = kmalloc_slab(size);

            if (!s)
                return ZERO_SIZE_PTR;

            return kmem_cache_alloc_trace(s, flags, size);
        }
    }
    return __kmalloc(size, flags);
}

#ifdef CONFIG_NUMA
void *__kmalloc_node(size_t size, gfp_t flags, int node);
void *kmem_cache_alloc_node(struct kmem_cache *, gfp_t flags, int node);

#ifdef CONFIG_TRACING
extern void *kmem_cache_alloc_node_trace(struct kmem_cache *s,
                       gfp_t gfpflags,
                       int node, size_t size);
#else
static __always_inline void *
kmem_cache_alloc_node_trace(struct kmem_cache *s,
                  gfp_t gfpflags,
                  int node, size_t size)
{
    return kmem_cache_alloc_node(s, gfpflags, node);
}
#endif

static __always_inline void *kmalloc_node(size_t size, gfp_t flags, int node)
{
    if (__builtin_constant_p(size) &&
        size <= SLUB_MAX_SIZE && !(flags & SLUB_DMA)) {
            struct kmem_cache *s = kmalloc_slab(size);

        if (!s)
            return ZERO_SIZE_PTR;

        return kmem_cache_alloc_node_trace(s, flags, node, size);
    }
    return __kmalloc_node(size, flags, node);
}
#endif

#endif /* _LINUX_SLUB_DEF_H */