mm/slab_common.c

   1 /*
   2  * Slab allocator functions that are independent of the allocator strategy
   3  *
   4  * (C) 2012 Christoph Lameter <cl@linux.com>
   5  */
   6 #include <linux/slab.h>
   7
   8 #include <linux/mm.h>
   9 #include <linux/poison.h>
  10 #include <linux/interrupt.h>
  11 #include <linux/memory.h>
  12 #include <linux/compiler.h>
  13 #include <linux/module.h>
  14 #include <linux/cpu.h>
  15 #include <linux/uaccess.h>
  16 #include <asm/cacheflush.h>
  17 #include <asm/tlbflush.h>
  18 #include <asm/page.h>
  19
  20 #include "slab.h"
  21
  22 enum slab_state slab_state;
  23 LIST_HEAD(slab_caches);
  24 DEFINE_MUTEX(slab_mutex);
  25 struct kmem_cache *kmem_cache;
  26
  27 #ifdef CONFIG_DEBUG_VM
  28 static int kmem_cache_sanity_check(const char *name, size_t size)
  29 {
  30         struct kmem_cache *s = NULL;
  31
  32         if (!name || in_interrupt() || size < sizeof(void *) ||
  33                 size > KMALLOC_MAX_SIZE) {
  34                 pr_err("kmem_cache_create(%s) integrity check failed\n", name);
  35                 return -EINVAL;
  36         }
  37
  38         list_for_each_entry(s, &slab_caches, list) {
  39                 char tmp;
  40                 int res;
  41
  42                 /*
  43                  * This happens when the module gets unloaded and doesn't
  44                  * destroy its slab cache and no-one else reuses the vmalloc
  45                  * area of the module.  Print a warning.
  46                  */
  47                 res = probe_kernel_address(s->name, tmp);
  48                 if (res) {
  49                         pr_err("Slab cache with size %d has lost its name\n",
  50                                s->object_size);
  51                         continue;
  52                 }
  53
  54                 if (!strcmp(s->name, name)) {
  55                         pr_err("%s (%s): Cache name already exists.\n",
  56                                __func__, name);
  57                         dump_stack();
  58                         s = NULL;
  59                         return -EINVAL;
  60                 }
  61         }
  62
  63         WARN_ON(strchr(name, ' '));     /* It confuses parsers */
  64         return 0;
  65 }
  66 #else
  67 static inline int kmem_cache_sanity_check(const char *name, size_t size)
  68 {
  69         return 0;
  70 }
  71 #endif
  72
  73 /*
  74  * kmem_cache_create - Create a cache.
  75  * @name: A string which is used in /proc/slabinfo to identify this cache.
  76  * @size: The size of objects to be created in this cache.
  77  * @align: The required alignment for the objects.
  78  * @flags: SLAB flags
  79  * @ctor: A constructor for the objects.
  80  *
  81  * Returns a ptr to the cache on success, NULL on failure.
  82  * Cannot be called within a interrupt, but can be interrupted.
  83  * The @ctor is run when new pages are allocated by the cache.
  84  *
  85  * The flags are
  86  *
  87  * %SLAB_POISON - Poison the slab with a known test pattern (a5a5a5a5)
  88  * to catch references to uninitialised memory.
  89  *
  90  * %SLAB_RED_ZONE - Insert `Red' zones around the allocated memory to check
  91  * for buffer overruns.
  92  *
  93  * %SLAB_HWCACHE_ALIGN - Align the objects in this cache to a hardware
  94  * cacheline.  This can be beneficial if you're counting cycles as closely
  95  * as davem.
  96  */
  97
  98 struct kmem_cache *kmem_cache_create(const char *name, size_t size, size_t align,
  99                 unsigned long flags, void (*ctor)(void *))
 100 {
 101         struct kmem_cache *s = NULL;
 102         int err = 0;
 103
 104         get_online_cpus();
 105         mutex_lock(&slab_mutex);
 106
 107         if (!kmem_cache_sanity_check(name, size) == 0)
 108                 goto out_locked;
 109
 110
 111         s = __kmem_cache_alias(name, size, align, flags, ctor);
 112         if (s)
 113                 goto out_locked;
 114
 115         s = kmem_cache_zalloc(kmem_cache, GFP_KERNEL);
 116         if (s) {
 117                 s->object_size = s->size = size;
 118                 s->align = align;
 119                 s->ctor = ctor;
 120                 s->name = kstrdup(name, GFP_KERNEL);
 121                 if (!s->name) {
 122                         kmem_cache_free(kmem_cache, s);
 123                         err = -ENOMEM;
 124                         goto out_locked;
 125                 }
 126
 127                 err = __kmem_cache_create(s, flags);
 128                 if (!err) {
 129
 130                         s->refcount = 1;
 131                         list_add(&s->list, &slab_caches);
 132
 133                 } else {
 134                         kfree(s->name);
 135                         kmem_cache_free(kmem_cache, s);
 136                 }
 137         } else
 138                 err = -ENOMEM;
 139
 140 out_locked:
 141         mutex_unlock(&slab_mutex);
 142         put_online_cpus();
 143
 144         if (err) {
 145
 146                 if (flags & SLAB_PANIC)
 147                         panic("kmem_cache_create: Failed to create slab '%s'. Error %d\n",
 148                                 name, err);
 149                 else {
 150                         printk(KERN_WARNING "kmem_cache_create(%s) failed with error %d",
 151                                 name, err);
 152                         dump_stack();
 153                 }
 154
 155                 return NULL;
 156         }
 157
 158         return s;
 159 }
 160 EXPORT_SYMBOL(kmem_cache_create);
 161
 162 void kmem_cache_destroy(struct kmem_cache *s)
 163 {
 164         get_online_cpus();
 165         mutex_lock(&slab_mutex);
 166         s->refcount--;
 167         if (!s->refcount) {
 168                 list_del(&s->list);
 169
 170                 if (!__kmem_cache_shutdown(s)) {
 171                         mutex_unlock(&slab_mutex);
 172                         if (s->flags & SLAB_DESTROY_BY_RCU)
 173                                 rcu_barrier();
 174
 175                         kfree(s->name);
 176                         kmem_cache_free(kmem_cache, s);
 177                 } else {
 178                         list_add(&s->list, &slab_caches);
 179                         mutex_unlock(&slab_mutex);
 180                         printk(KERN_ERR "kmem_cache_destroy %s: Slab cache still has objects\n",
 181                                 s->name);
 182                         dump_stack();
 183                 }
 184         } else {
 185                 mutex_unlock(&slab_mutex);
 186         }
 187         put_online_cpus();
 188 }
 189 EXPORT_SYMBOL(kmem_cache_destroy);
 190
 191 int slab_is_available(void)
 192 {
 193         return slab_state >= UP;
 194 }