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
  26 #ifdef CONFIG_DEBUG_VM
  27 static int kmem_cache_sanity_check(const char *name, size_t size)
  28 {
  29         struct kmem_cache *s = NULL;
  30
  31         if (!name || in_interrupt() || size < sizeof(void *) ||
  32                 size > KMALLOC_MAX_SIZE) {
  33                 pr_err("kmem_cache_create(%s) integrity check failed\n", name);
  34                 return -EINVAL;
  35         }
  36
  37         list_for_each_entry(s, &slab_caches, list) {
  38                 char tmp;
  39                 int res;
  40
  41                 /*
  42                  * This happens when the module gets unloaded and doesn't
  43                  * destroy its slab cache and no-one else reuses the vmalloc
  44                  * area of the module.  Print a warning.
  45                  */
  46                 res = probe_kernel_address(s->name, tmp);
  47                 if (res) {
  48                         pr_err("Slab cache with size %d has lost its name\n",
  49                                s->object_size);
  50                         continue;
  51                 }
  52
  53                 if (!strcmp(s->name, name)) {
  54                         pr_err("%s (%s): Cache name already exists.\n",
  55                                __func__, name);
  56                         dump_stack();
  57                         s = NULL;
  58                         return -EINVAL;
  59                 }
  60         }
  61
  62         WARN_ON(strchr(name, ' '));     /* It confuses parsers */
  63         return 0;
  64 }
  65 #else
  66 static inline int kmem_cache_sanity_check(const char *name, size_t size)
  67 {
  68         return 0;
  69 }
  70 #endif
  71
  72 /*
  73  * kmem_cache_create - Create a cache.
  74  * @name: A string which is used in /proc/slabinfo to identify this cache.
  75  * @size: The size of objects to be created in this cache.
  76  * @align: The required alignment for the objects.
  77  * @flags: SLAB flags
  78  * @ctor: A constructor for the objects.
  79  *
  80  * Returns a ptr to the cache on success, NULL on failure.
  81  * Cannot be called within a interrupt, but can be interrupted.
  82  * The @ctor is run when new pages are allocated by the cache.
  83  *
  84  * The flags are
  85  *
  86  * %SLAB_POISON - Poison the slab with a known test pattern (a5a5a5a5)
  87  * to catch references to uninitialised memory.
  88  *
  89  * %SLAB_RED_ZONE - Insert `Red' zones around the allocated memory to check
  90  * for buffer overruns.
  91  *
  92  * %SLAB_HWCACHE_ALIGN - Align the objects in this cache to a hardware
  93  * cacheline.  This can be beneficial if you're counting cycles as closely
  94  * as davem.
  95  */
  96
  97 struct kmem_cache *kmem_cache_create(const char *name, size_t size, size_t align,
  98                 unsigned long flags, void (*ctor)(void *))
  99 {
 100         struct kmem_cache *s = NULL;
 101         int err = 0;
 102
 103         get_online_cpus();
 104         mutex_lock(&slab_mutex);
 105
 106         if (!kmem_cache_sanity_check(name, size) == 0)
 107                 goto out_locked;
 108
 109
 110         s = __kmem_cache_create(name, size, align, flags, ctor);
 111         if (!s)
 112                 err = -ENOSYS; /* Until __kmem_cache_create returns code */
 113
 114         /*
 115          * Check if the slab has actually been created and if it was a
 116          * real instatiation. Aliases do not belong on the list
 117          */
 118         if (s && s->refcount == 1)
 119                 list_add(&s->list, &slab_caches);
 120
 121 out_locked:
 122         mutex_unlock(&slab_mutex);
 123         put_online_cpus();
 124
 125         if (err) {
 126
 127                 if (flags & SLAB_PANIC)
 128                         panic("kmem_cache_create: Failed to create slab '%s'. Error %d\n",
 129                                 name, err);
 130                 else {
 131                         printk(KERN_WARNING "kmem_cache_create(%s) failed with error %d",
 132                                 name, err);
 133                         dump_stack();
 134                 }
 135
 136                 return NULL;
 137         }
 138
 139         return s;
 140 }
 141 EXPORT_SYMBOL(kmem_cache_create);
 142
 143 void kmem_cache_destroy(struct kmem_cache *s)
 144 {
 145         get_online_cpus();
 146         mutex_lock(&slab_mutex);
 147         s->refcount--;
 148         if (!s->refcount) {
 149                 list_del(&s->list);
 150
 151                 if (!__kmem_cache_shutdown(s)) {
 152                         if (s->flags & SLAB_DESTROY_BY_RCU)
 153                                 rcu_barrier();
 154
 155                         __kmem_cache_destroy(s);
 156                 } else {
 157                         list_add(&s->list, &slab_caches);
 158                         printk(KERN_ERR "kmem_cache_destroy %s: Slab cache still has objects\n",
 159                                 s->name);
 160                         dump_stack();
 161                 }
 162         }
 163         mutex_unlock(&slab_mutex);
 164         put_online_cpus();
 165 }
 166 EXPORT_SYMBOL(kmem_cache_destroy);
 167
 168 int slab_is_available(void)
 169 {
 170         return slab_state >= UP;
 171 }