modules/spl/spl-kmem.c

   1 #include <sys/kmem.h>
   2
   3 /*
   4  * Memory allocation interfaces
   5  */
   6 #ifdef DEBUG_KMEM
   7 /* Shim layer memory accounting */
   8 atomic64_t kmem_alloc_used;
   9 unsigned long kmem_alloc_max = 0;
  10 atomic64_t vmem_alloc_used;
  11 unsigned long vmem_alloc_max = 0;
  12 int kmem_warning_flag = 1;
  13
  14 EXPORT_SYMBOL(kmem_alloc_used);
  15 EXPORT_SYMBOL(kmem_alloc_max);
  16 EXPORT_SYMBOL(vmem_alloc_used);
  17 EXPORT_SYMBOL(vmem_alloc_max);
  18 EXPORT_SYMBOL(kmem_warning_flag);
  19
  20 int kmem_set_warning(int flag) { return (kmem_warning_flag = !!flag); }
  21 #else
  22 int kmem_set_warning(int flag) { return 0; }
  23 #endif
  24 EXPORT_SYMBOL(kmem_set_warning);
  25
  26 /*
  27  * Slab allocation interfaces
  28  *
  29  * While the linux slab implementation was inspired by solaris they
  30  * have made some changes to the API which complicates this shim
  31  * layer.  For one thing the same symbol names are used with different
  32  * arguments for the prototypes.  To deal with this we must use the
  33  * preprocessor to re-order arguments.  Happily for us standard C says,
  34  * "Macro's appearing in their own expansion are not reexpanded" so
  35  * this does not result in an infinite recursion.  Additionally the
  36  * function pointers registered by solarias differ from those used
  37  * by linux so a lookup and mapping from linux style callback to a
  38  * solaris style callback is needed.  There is some overhead in this
  39  * operation which isn't horibile but it needs to be kept in mind.
  40  */
  41 typedef struct kmem_cache_cb {
  42         struct list_head    kcc_list;
  43         kmem_cache_t *      kcc_cache;
  44         kmem_constructor_t  kcc_constructor;
  45         kmem_destructor_t   kcc_destructor;
  46         kmem_reclaim_t      kcc_reclaim;
  47         void *              kcc_private;
  48         void *              kcc_vmp;
  49 } kmem_cache_cb_t;
  50
  51
  52 static spinlock_t kmem_cache_cb_lock = SPIN_LOCK_UNLOCKED;
  53 //static spinlock_t kmem_cache_cb_lock = (spinlock_t) { 1 SPINLOCK_MAGIC_INIT };
  54 static LIST_HEAD(kmem_cache_cb_list);
  55 static struct shrinker *kmem_cache_shrinker;
  56
  57 /* Function must be called while holding the kmem_cache_cb_lock
  58  * Because kmem_cache_t is an opaque datatype we're forced to
  59  * match pointers to identify specific cache entires.
  60  */
  61 static kmem_cache_cb_t *
  62 kmem_cache_find_cache_cb(kmem_cache_t *cache)
  63 {
  64         kmem_cache_cb_t *kcc;
  65
  66         list_for_each_entry(kcc, &kmem_cache_cb_list, kcc_list)
  67                 if (cache == kcc->kcc_cache)
  68                         return kcc;
  69
  70         return NULL;
  71 }
  72
  73 static kmem_cache_cb_t *
  74 kmem_cache_add_cache_cb(kmem_cache_t *cache,
  75                         kmem_constructor_t constructor,
  76                         kmem_destructor_t destructor,
  77                         kmem_reclaim_t reclaim,
  78                         void *priv, void *vmp)
  79 {
  80         kmem_cache_cb_t *kcc;
  81
  82         kcc = (kmem_cache_cb_t *)kmalloc(sizeof(*kcc), GFP_KERNEL);
  83         if (kcc) {
  84                 kcc->kcc_cache = cache;
  85                 kcc->kcc_constructor = constructor;
  86                 kcc->kcc_destructor = destructor;
  87                 kcc->kcc_reclaim = reclaim;
  88                 kcc->kcc_private = priv;
  89                 kcc->kcc_vmp = vmp;
  90                 spin_lock(&kmem_cache_cb_lock);
  91                 list_add(&kcc->kcc_list, &kmem_cache_cb_list);
  92                 spin_unlock(&kmem_cache_cb_lock);
  93         }
  94
  95         return kcc;
  96 }
  97
  98 static void
  99 kmem_cache_remove_cache_cb(kmem_cache_cb_t *kcc)
 100 {
 101         spin_lock(&kmem_cache_cb_lock);
 102         list_del(&kcc->kcc_list);
 103         spin_unlock(&kmem_cache_cb_lock);
 104
 105        if (kcc)
 106               kfree(kcc);
 107 }
 108
 109 static void
 110 kmem_cache_generic_constructor(void *ptr, kmem_cache_t *cache, unsigned long flags)
 111 {
 112         kmem_cache_cb_t *kcc;
 113
 114         spin_lock(&kmem_cache_cb_lock);
 115
 116         /* Callback list must be in sync with linux slab caches */
 117         kcc = kmem_cache_find_cache_cb(cache);
 118         BUG_ON(!kcc);
 119
 120         kcc->kcc_constructor(ptr, kcc->kcc_private, (int)flags);
 121         spin_unlock(&kmem_cache_cb_lock);
 122         /* Linux constructor has no return code, silently eat it */
 123 }
 124
 125 static void
 126 kmem_cache_generic_destructor(void *ptr, kmem_cache_t *cache, unsigned long flags)
 127 {
 128         kmem_cache_cb_t *kcc;
 129
 130         spin_lock(&kmem_cache_cb_lock);
 131
 132         /* Callback list must be in sync with linux slab caches */
 133         kcc = kmem_cache_find_cache_cb(cache);
 134         BUG_ON(!kcc);
 135
 136         /* Solaris destructor takes no flags, silently eat them */
 137         kcc->kcc_destructor(ptr, kcc->kcc_private);
 138         spin_unlock(&kmem_cache_cb_lock);
 139 }
 140
 141 /* XXX - Arguments are ignored */
 142 static int
 143 kmem_cache_generic_shrinker(int nr_to_scan, unsigned int gfp_mask)
 144 {
 145         kmem_cache_cb_t *kcc;
 146         int total = 0;
 147
 148         /* Under linux a shrinker is not tightly coupled with a slab
 149          * cache.  In fact linux always systematically trys calling all
 150          * registered shrinker callbacks until its target reclamation level
 151          * is reached.  Because of this we only register one shrinker
 152          * function in the shim layer for all slab caches.  And we always
 153          * attempt to shrink all caches when this generic shrinker is called.
 154          */
 155         spin_lock(&kmem_cache_cb_lock);
 156
 157         list_for_each_entry(kcc, &kmem_cache_cb_list, kcc_list) {
 158                 /* Under linux the desired number and gfp type of objects
 159                  * is passed to the reclaiming function as a sugested reclaim
 160                  * target.  I do not pass these args on because reclaim
 161                  * policy is entirely up to the owner under solaris.  We only
 162                  * pass on the pre-registered private data.
 163                  */
 164                 if (kcc->kcc_reclaim)
 165                         kcc->kcc_reclaim(kcc->kcc_private);
 166
 167                 total += 1;
 168         }
 169
 170         /* Under linux we should return the remaining number of entires in
 171          * the cache.  Unfortunately, I don't see an easy way to safely
 172          * emulate this behavior so I'm returning one entry per cache which
 173          * was registered with the generic shrinker.  This should fake out
 174          * the linux VM when it attempts to shrink caches.
 175          */
 176         spin_unlock(&kmem_cache_cb_lock);
 177         return total;
 178 }
 179
 180 /* Ensure the __kmem_cache_create/__kmem_cache_destroy macros are
 181  * removed here to prevent a recursive substitution, we want to call
 182  * the native linux version.
 183  */
 184 #undef kmem_cache_create
 185 #undef kmem_cache_destroy
 186
 187 kmem_cache_t *
 188 __kmem_cache_create(char *name, size_t size, size_t align,
 189         kmem_constructor_t constructor,
 190         kmem_destructor_t destructor,
 191         kmem_reclaim_t reclaim,
 192         void *priv, void *vmp, int flags)
 193 {
 194         kmem_cache_t *cache;
 195         kmem_cache_cb_t *kcc;
 196         int shrinker_flag = 0;
 197         char *cache_name;
 198
 199         /* FIXME: - Option currently unsupported by shim layer */
 200         BUG_ON(vmp);
 201
 202         cache_name = kzalloc(strlen(name) + 1, GFP_KERNEL);
 203         if (cache_name == NULL)
 204                 return NULL;
 205
 206         strcpy(cache_name, name);
 207         cache = kmem_cache_create(cache_name, size, align, flags,
 208                                   kmem_cache_generic_constructor,
 209                                   kmem_cache_generic_destructor);
 210         if (cache == NULL)
 211                 return NULL;
 212
 213         /* Register shared shrinker function on initial cache create */
 214         spin_lock(&kmem_cache_cb_lock);
 215         if (list_empty(&kmem_cache_cb_list)) {
 216                 kmem_cache_shrinker = set_shrinker(KMC_DEFAULT_SEEKS,
 217                                                  kmem_cache_generic_shrinker);
 218                 if (kmem_cache_shrinker == NULL) {
 219                         kmem_cache_destroy(cache);
 220                         spin_unlock(&kmem_cache_cb_lock);
 221                         return NULL;
 222                 }
 223
 224         }
 225         spin_unlock(&kmem_cache_cb_lock);
 226
 227         kcc = kmem_cache_add_cache_cb(cache, constructor, destructor,
 228                                       reclaim, priv, vmp);
 229         if (kcc == NULL) {
 230                 if (shrinker_flag) /* New shrinker registered must be removed */
 231                         remove_shrinker(kmem_cache_shrinker);
 232
 233                 kmem_cache_destroy(cache);
 234                 return NULL;
 235         }
 236
 237         return cache;
 238 }
 239 EXPORT_SYMBOL(__kmem_cache_create);
 240
 241 /* Return code provided despite Solaris's void return.  There should be no
 242  * harm here since the Solaris versions will ignore it anyway. */
 243 int
 244 __kmem_cache_destroy(kmem_cache_t *cache)
 245 {
 246         kmem_cache_cb_t *kcc;
 247         char *name;
 248         int rc;
 249
 250         spin_lock(&kmem_cache_cb_lock);
 251         kcc = kmem_cache_find_cache_cb(cache);
 252         spin_unlock(&kmem_cache_cb_lock);
 253         if (kcc == NULL)
 254                 return -EINVAL;
 255
 256         name = (char *)kmem_cache_name(cache);
 257         rc = kmem_cache_destroy(cache);
 258         kmem_cache_remove_cache_cb(kcc);
 259         kfree(name);
 260
 261         /* Unregister generic shrinker on removal of all caches */
 262         spin_lock(&kmem_cache_cb_lock);
 263         if (list_empty(&kmem_cache_cb_list))
 264                 remove_shrinker(kmem_cache_shrinker);
 265
 266         spin_unlock(&kmem_cache_cb_lock);
 267         return rc;
 268 }
 269 EXPORT_SYMBOL(__kmem_cache_destroy);
 270
 271 void
 272 __kmem_reap(void) {
 273         /* Since there's no easy hook in to linux to force all the registered
 274          * shrinkers to run we just run the ones registered for this shim */
 275         kmem_cache_generic_shrinker(KMC_REAP_CHUNK, GFP_KERNEL);
 276 }
 277 EXPORT_SYMBOL(__kmem_reap);
 278
 279 int
 280 kmem_init(void)
 281 {
 282 #ifdef DEBUG_KMEM
 283         atomic64_set(&kmem_alloc_used, 0);
 284         atomic64_set(&vmem_alloc_used, 0);
 285 #endif
 286         return 0;
 287 }
 288
 289 void
 290 kmem_fini(void)
 291 {
 292 #ifdef DEBUG_KMEM
 293         if (atomic64_read(&kmem_alloc_used) != 0)
 294                 printk("spl: Warning kmem leaked %ld/%ld bytes\n",
 295                        atomic_read(&kmem_alloc_used), kmem_alloc_max);
 296
 297         if (atomic64_read(&vmem_alloc_used) != 0)
 298                 printk("spl: Warning vmem leaked %ld/%ld bytes\n",
 299                        atomic_read(&vmem_alloc_used), vmem_alloc_max);
 300 #endif
 301 }