include/linux/slub_def.h

   1 #ifndef _LINUX_SLUB_DEF_H
   2 #define _LINUX_SLUB_DEF_H
   3
   4 /*
   5  * SLUB : A Slab allocator without object queues.
   6  *
   7  * (C) 2007 SGI, Christoph Lameter <clameter@sgi.com>
   8  */
   9 #include <linux/types.h>
  10 #include <linux/gfp.h>
  11 #include <linux/workqueue.h>
  12 #include <linux/kobject.h>
  13
  14 struct kmem_cache_node {
  15         spinlock_t list_lock;   /* Protect partial list and nr_partial */
  16         unsigned long nr_partial;
  17         atomic_long_t nr_slabs;
  18         struct list_head partial;
  19         struct list_head full;
  20 };
  21
  22 /*
  23  * Slab cache management.
  24  */
  25 struct kmem_cache {
  26         /* Used for retriving partial slabs etc */
  27         unsigned long flags;
  28         int size;               /* The size of an object including meta data */
  29         int objsize;            /* The size of an object without meta data */
  30         int offset;             /* Free pointer offset. */
  31         unsigned int order;
  32
  33         /*
  34          * Avoid an extra cache line for UP, SMP and for the node local to
  35          * struct kmem_cache.
  36          */
  37         struct kmem_cache_node local_node;
  38
  39         /* Allocation and freeing of slabs */
  40         int objects;            /* Number of objects in slab */
  41         int refcount;           /* Refcount for slab cache destroy */
  42         void (*ctor)(void *, struct kmem_cache *, unsigned long);
  43         int inuse;              /* Offset to metadata */
  44         int align;              /* Alignment */
  45         const char *name;       /* Name (only for display!) */
  46         struct list_head list;  /* List of slab caches */
  47         struct kobject kobj;    /* For sysfs */
  48
  49 #ifdef CONFIG_NUMA
  50         int defrag_ratio;
  51         struct kmem_cache_node *node[MAX_NUMNODES];
  52 #endif
  53         struct page *cpu_slab[NR_CPUS];
  54 };
  55
  56 /*
  57  * Kmalloc subsystem.
  58  */
  59 #define KMALLOC_SHIFT_LOW 3
  60
  61 /*
  62  * We keep the general caches in an array of slab caches that are used for
  63  * 2^x bytes of allocations.
  64  */
  65 extern struct kmem_cache kmalloc_caches[KMALLOC_SHIFT_HIGH + 1];
  66
  67 /*
  68  * Sorry that the following has to be that ugly but some versions of GCC
  69  * have trouble with constant propagation and loops.
  70  */
  71 static inline int kmalloc_index(size_t size)
  72 {
  73         if (!size)
  74                 return 0;
  75
  76         if (size > KMALLOC_MAX_SIZE)
  77                 return -1;
  78
  79         if (size > 64 && size <= 96)
  80                 return 1;
  81         if (size > 128 && size <= 192)
  82                 return 2;
  83         if (size <=          8) return 3;
  84         if (size <=         16) return 4;
  85         if (size <=         32) return 5;
  86         if (size <=         64) return 6;
  87         if (size <=        128) return 7;
  88         if (size <=        256) return 8;
  89         if (size <=        512) return 9;
  90         if (size <=       1024) return 10;
  91         if (size <=   2 * 1024) return 11;
  92         if (size <=   4 * 1024) return 12;
  93         if (size <=   8 * 1024) return 13;
  94         if (size <=  16 * 1024) return 14;
  95         if (size <=  32 * 1024) return 15;
  96         if (size <=  64 * 1024) return 16;
  97         if (size <= 128 * 1024) return 17;
  98         if (size <= 256 * 1024) return 18;
  99         if (size <=  512 * 1024) return 19;
 100         if (size <= 1024 * 1024) return 20;
 101         if (size <=  2 * 1024 * 1024) return 21;
 102         if (size <=  4 * 1024 * 1024) return 22;
 103         if (size <=  8 * 1024 * 1024) return 23;
 104         if (size <= 16 * 1024 * 1024) return 24;
 105         if (size <= 32 * 1024 * 1024) return 25;
 106         return -1;
 107
 108 /*
 109  * What we really wanted to do and cannot do because of compiler issues is:
 110  *      int i;
 111  *      for (i = KMALLOC_SHIFT_LOW; i <= KMALLOC_SHIFT_HIGH; i++)
 112  *              if (size <= (1 << i))
 113  *                      return i;
 114  */
 115 }
 116
 117 /*
 118  * Find the slab cache for a given combination of allocation flags and size.
 119  *
 120  * This ought to end up with a global pointer to the right cache
 121  * in kmalloc_caches.
 122  */
 123 static inline struct kmem_cache *kmalloc_slab(size_t size)
 124 {
 125         int index = kmalloc_index(size);
 126
 127         if (index == 0)
 128                 return NULL;
 129
 130         /*
 131          * This function only gets expanded if __builtin_constant_p(size), so
 132          * testing it here shouldn't be needed.  But some versions of gcc need
 133          * help.
 134          */
 135         if (__builtin_constant_p(size) && index < 0) {
 136                 /*
 137                  * Generate a link failure. Would be great if we could
 138                  * do something to stop the compile here.
 139                  */
 140                 extern void __kmalloc_size_too_large(void);
 141                 __kmalloc_size_too_large();
 142         }
 143         return &kmalloc_caches[index];
 144 }
 145
 146 #ifdef CONFIG_ZONE_DMA
 147 #define SLUB_DMA __GFP_DMA
 148 #else
 149 /* Disable DMA functionality */
 150 #define SLUB_DMA 0
 151 #endif
 152
 153
 154 /*
 155  * ZERO_SIZE_PTR will be returned for zero sized kmalloc requests.
 156  *
 157  * Dereferencing ZERO_SIZE_PTR will lead to a distinct access fault.
 158  *
 159  * ZERO_SIZE_PTR can be passed to kfree though in the same way that NULL can.
 160  * Both make kfree a no-op.
 161  */
 162 #define ZERO_SIZE_PTR ((void *)16)
 163
 164
 165 static inline void *kmalloc(size_t size, gfp_t flags)
 166 {
 167         if (__builtin_constant_p(size) && !(flags & SLUB_DMA)) {
 168                 struct kmem_cache *s = kmalloc_slab(size);
 169
 170                 if (!s)
 171                         return ZERO_SIZE_PTR;
 172
 173                 return kmem_cache_alloc(s, flags);
 174         } else
 175                 return __kmalloc(size, flags);
 176 }
 177
 178 static inline void *kzalloc(size_t size, gfp_t flags)
 179 {
 180         if (__builtin_constant_p(size) && !(flags & SLUB_DMA)) {
 181                 struct kmem_cache *s = kmalloc_slab(size);
 182
 183                 if (!s)
 184                         return ZERO_SIZE_PTR;
 185
 186                 return kmem_cache_zalloc(s, flags);
 187         } else
 188                 return __kzalloc(size, flags);
 189 }
 190
 191 #ifdef CONFIG_NUMA
 192 extern void *__kmalloc_node(size_t size, gfp_t flags, int node);
 193
 194 static inline void *kmalloc_node(size_t size, gfp_t flags, int node)
 195 {
 196         if (__builtin_constant_p(size) && !(flags & SLUB_DMA)) {
 197                 struct kmem_cache *s = kmalloc_slab(size);
 198
 199                 if (!s)
 200                         return ZERO_SIZE_PTR;
 201
 202                 return kmem_cache_alloc_node(s, flags, node);
 203         } else
 204                 return __kmalloc_node(size, flags, node);
 205 }
 206 #endif
 207
 208 #endif /* _LINUX_SLUB_DEF_H */