drivers/gpu/drm/drm_mm.c

   1 /**************************************************************************
   2  *
   3  * Copyright 2006 Tungsten Graphics, Inc., Bismarck, ND., USA.
   4  * All Rights Reserved.
   5  *
   6  * Permission is hereby granted, free of charge, to any person obtaining a
   7  * copy of this software and associated documentation files (the
   8  * "Software"), to deal in the Software without restriction, including
   9  * without limitation the rights to use, copy, modify, merge, publish,
  10  * distribute, sub license, and/or sell copies of the Software, and to
  11  * permit persons to whom the Software is furnished to do so, subject to
  12  * the following conditions:
  13  *
  14  * The above copyright notice and this permission notice (including the
  15  * next paragraph) shall be included in all copies or substantial portions
  16  * of the Software.
  17  *
  18  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  19  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  20  * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
  21  * THE COPYRIGHT HOLDERS, AUTHORS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM,
  22  * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
  23  * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
  24  * USE OR OTHER DEALINGS IN THE SOFTWARE.
  25  *
  26  *
  27  **************************************************************************/
  28
  29 /*
  30  * Generic simple memory manager implementation. Intended to be used as a base
  31  * class implementation for more advanced memory managers.
  32  *
  33  * Note that the algorithm used is quite simple and there might be substantial
  34  * performance gains if a smarter free list is implemented. Currently it is just an
  35  * unordered stack of free regions. This could easily be improved if an RB-tree
  36  * is used instead. At least if we expect heavy fragmentation.
  37  *
  38  * Aligned allocations can also see improvement.
  39  *
  40  * Authors:
  41  * Thomas Hellström <thomas-at-tungstengraphics-dot-com>
  42  */
  43
  44 #include "drmP.h"
  45 #include "drm_mm.h"
  46 #include <linux/slab.h>
  47
  48 #define MM_UNUSED_TARGET 4
  49
  50 unsigned long drm_mm_tail_space(struct drm_mm *mm)
  51 {
  52         struct list_head *tail_node;
  53         struct drm_mm_node *entry;
  54
  55         tail_node = mm->ml_entry.prev;
  56         entry = list_entry(tail_node, struct drm_mm_node, ml_entry);
  57         if (!entry->free)
  58                 return 0;
  59
  60         return entry->size;
  61 }
  62
  63 int drm_mm_remove_space_from_tail(struct drm_mm *mm, unsigned long size)
  64 {
  65         struct list_head *tail_node;
  66         struct drm_mm_node *entry;
  67
  68         tail_node = mm->ml_entry.prev;
  69         entry = list_entry(tail_node, struct drm_mm_node, ml_entry);
  70         if (!entry->free)
  71                 return -ENOMEM;
  72
  73         if (entry->size <= size)
  74                 return -ENOMEM;
  75
  76         entry->size -= size;
  77         return 0;
  78 }
  79
  80 static struct drm_mm_node *drm_mm_kmalloc(struct drm_mm *mm, int atomic)
  81 {
  82         struct drm_mm_node *child;
  83
  84         if (atomic)
  85                 child = kmalloc(sizeof(*child), GFP_ATOMIC);
  86         else
  87                 child = kmalloc(sizeof(*child), GFP_KERNEL);
  88
  89         if (unlikely(child == NULL)) {
  90                 spin_lock(&mm->unused_lock);
  91                 if (list_empty(&mm->unused_nodes))
  92                         child = NULL;
  93                 else {
  94                         child =
  95                             list_entry(mm->unused_nodes.next,
  96                                        struct drm_mm_node, fl_entry);
  97                         list_del(&child->fl_entry);
  98                         --mm->num_unused;
  99                 }
 100                 spin_unlock(&mm->unused_lock);
 101         }
 102         return child;
 103 }
 104
 105 int drm_mm_pre_get(struct drm_mm *mm)
 106 {
 107         struct drm_mm_node *node;
 108
 109         spin_lock(&mm->unused_lock);
 110         while (mm->num_unused < MM_UNUSED_TARGET) {
 111                 spin_unlock(&mm->unused_lock);
 112                 node = kmalloc(sizeof(*node), GFP_KERNEL);
 113                 spin_lock(&mm->unused_lock);
 114
 115                 if (unlikely(node == NULL)) {
 116                         int ret = (mm->num_unused < 2) ? -ENOMEM : 0;
 117                         spin_unlock(&mm->unused_lock);
 118                         return ret;
 119                 }
 120                 ++mm->num_unused;
 121                 list_add_tail(&node->fl_entry, &mm->unused_nodes);
 122         }
 123         spin_unlock(&mm->unused_lock);
 124         return 0;
 125 }
 126 EXPORT_SYMBOL(drm_mm_pre_get);
 127
 128 static int drm_mm_create_tail_node(struct drm_mm *mm,
 129                                    unsigned long start,
 130                                    unsigned long size, int atomic)
 131 {
 132         struct drm_mm_node *child;
 133
 134         child = drm_mm_kmalloc(mm, atomic);
 135         if (unlikely(child == NULL))
 136                 return -ENOMEM;
 137
 138         child->free = 1;
 139         child->size = size;
 140         child->start = start;
 141         child->mm = mm;
 142
 143         list_add_tail(&child->ml_entry, &mm->ml_entry);
 144         list_add_tail(&child->fl_entry, &mm->fl_entry);
 145
 146         return 0;
 147 }
 148
 149 int drm_mm_add_space_to_tail(struct drm_mm *mm, unsigned long size, int atomic)
 150 {
 151         struct list_head *tail_node;
 152         struct drm_mm_node *entry;
 153
 154         tail_node = mm->ml_entry.prev;
 155         entry = list_entry(tail_node, struct drm_mm_node, ml_entry);
 156         if (!entry->free) {
 157                 return drm_mm_create_tail_node(mm, entry->start + entry->size,
 158                                                size, atomic);
 159         }
 160         entry->size += size;
 161         return 0;
 162 }
 163
 164 static struct drm_mm_node *drm_mm_split_at_start(struct drm_mm_node *parent,
 165                                                  unsigned long size,
 166                                                  int atomic)
 167 {
 168         struct drm_mm_node *child;
 169
 170         child = drm_mm_kmalloc(parent->mm, atomic);
 171         if (unlikely(child == NULL))
 172                 return NULL;
 173
 174         INIT_LIST_HEAD(&child->fl_entry);
 175
 176         child->free = 0;
 177         child->size = size;
 178         child->start = parent->start;
 179         child->mm = parent->mm;
 180
 181         list_add_tail(&child->ml_entry, &parent->ml_entry);
 182         INIT_LIST_HEAD(&child->fl_entry);
 183
 184         parent->size -= size;
 185         parent->start += size;
 186         return child;
 187 }
 188
 189
 190 struct drm_mm_node *drm_mm_get_block_generic(struct drm_mm_node *node,
 191                                              unsigned long size,
 192                                              unsigned alignment,
 193                                              int atomic)
 194 {
 195
 196         struct drm_mm_node *align_splitoff = NULL;
 197         unsigned tmp = 0;
 198
 199         if (alignment)
 200                 tmp = node->start % alignment;
 201
 202         if (tmp) {
 203                 align_splitoff =
 204                     drm_mm_split_at_start(node, alignment - tmp, atomic);
 205                 if (unlikely(align_splitoff == NULL))
 206                         return NULL;
 207         }
 208
 209         if (node->size == size) {
 210                 list_del_init(&node->fl_entry);
 211                 node->free = 0;
 212         } else {
 213                 node = drm_mm_split_at_start(node, size, atomic);
 214         }
 215
 216         if (align_splitoff)
 217                 drm_mm_put_block(align_splitoff);
 218
 219         return node;
 220 }
 221 EXPORT_SYMBOL(drm_mm_get_block_generic);
 222
 223 /*
 224  * Put a block. Merge with the previous and / or next block if they are free.
 225  * Otherwise add to the free stack.
 226  */
 227
 228 void drm_mm_put_block(struct drm_mm_node *cur)
 229 {
 230
 231         struct drm_mm *mm = cur->mm;
 232         struct list_head *cur_head = &cur->ml_entry;
 233         struct list_head *root_head = &mm->ml_entry;
 234         struct drm_mm_node *prev_node = NULL;
 235         struct drm_mm_node *next_node;
 236
 237         int merged = 0;
 238
 239         if (cur_head->prev != root_head) {
 240                 prev_node =
 241                     list_entry(cur_head->prev, struct drm_mm_node, ml_entry);
 242                 if (prev_node->free) {
 243                         prev_node->size += cur->size;
 244                         merged = 1;
 245                 }
 246         }
 247         if (cur_head->next != root_head) {
 248                 next_node =
 249                     list_entry(cur_head->next, struct drm_mm_node, ml_entry);
 250                 if (next_node->free) {
 251                         if (merged) {
 252                                 prev_node->size += next_node->size;
 253                                 list_del(&next_node->ml_entry);
 254                                 list_del(&next_node->fl_entry);
 255                                 if (mm->num_unused < MM_UNUSED_TARGET) {
 256                                         list_add(&next_node->fl_entry,
 257                                                  &mm->unused_nodes);
 258                                         ++mm->num_unused;
 259                                 } else
 260                                         kfree(next_node);
 261                         } else {
 262                                 next_node->size += cur->size;
 263                                 next_node->start = cur->start;
 264                                 merged = 1;
 265                         }
 266                 }
 267         }
 268         if (!merged) {
 269                 cur->free = 1;
 270                 list_add(&cur->fl_entry, &mm->fl_entry);
 271         } else {
 272                 list_del(&cur->ml_entry);
 273                 if (mm->num_unused < MM_UNUSED_TARGET) {
 274                         list_add(&cur->fl_entry, &mm->unused_nodes);
 275                         ++mm->num_unused;
 276                 } else
 277                         kfree(cur);
 278         }
 279 }
 280
 281 EXPORT_SYMBOL(drm_mm_put_block);
 282
 283 struct drm_mm_node *drm_mm_search_free(const struct drm_mm *mm,
 284                                        unsigned long size,
 285                                        unsigned alignment, int best_match)
 286 {
 287         struct list_head *list;
 288         const struct list_head *free_stack = &mm->fl_entry;
 289         struct drm_mm_node *entry;
 290         struct drm_mm_node *best;
 291         unsigned long best_size;
 292         unsigned wasted;
 293
 294         best = NULL;
 295         best_size = ~0UL;
 296
 297         list_for_each(list, free_stack) {
 298                 entry = list_entry(list, struct drm_mm_node, fl_entry);
 299                 wasted = 0;
 300
 301                 if (entry->size < size)
 302                         continue;
 303
 304                 if (alignment) {
 305                         register unsigned tmp = entry->start % alignment;
 306                         if (tmp)
 307                                 wasted += alignment - tmp;
 308                 }
 309
 310                 if (entry->size >= size + wasted) {
 311                         if (!best_match)
 312                                 return entry;
 313                         if (size < best_size) {
 314                                 best = entry;
 315                                 best_size = entry->size;
 316                         }
 317                 }
 318         }
 319
 320         return best;
 321 }
 322 EXPORT_SYMBOL(drm_mm_search_free);
 323
 324 int drm_mm_clean(struct drm_mm * mm)
 325 {
 326         struct list_head *head = &mm->ml_entry;
 327
 328         return (head->next->next == head);
 329 }
 330 EXPORT_SYMBOL(drm_mm_clean);
 331
 332 int drm_mm_init(struct drm_mm * mm, unsigned long start, unsigned long size)
 333 {
 334         INIT_LIST_HEAD(&mm->ml_entry);
 335         INIT_LIST_HEAD(&mm->fl_entry);
 336         INIT_LIST_HEAD(&mm->unused_nodes);
 337         mm->num_unused = 0;
 338         spin_lock_init(&mm->unused_lock);
 339
 340         return drm_mm_create_tail_node(mm, start, size, 0);
 341 }
 342 EXPORT_SYMBOL(drm_mm_init);
 343
 344 void drm_mm_takedown(struct drm_mm * mm)
 345 {
 346         struct list_head *bnode = mm->fl_entry.next;
 347         struct drm_mm_node *entry;
 348         struct drm_mm_node *next;
 349
 350         entry = list_entry(bnode, struct drm_mm_node, fl_entry);
 351
 352         if (entry->ml_entry.next != &mm->ml_entry ||
 353             entry->fl_entry.next != &mm->fl_entry) {
 354                 DRM_ERROR("Memory manager not clean. Delaying takedown\n");
 355                 return;
 356         }
 357
 358         list_del(&entry->fl_entry);
 359         list_del(&entry->ml_entry);
 360         kfree(entry);
 361
 362         spin_lock(&mm->unused_lock);
 363         list_for_each_entry_safe(entry, next, &mm->unused_nodes, fl_entry) {
 364                 list_del(&entry->fl_entry);
 365                 kfree(entry);
 366                 --mm->num_unused;
 367         }
 368         spin_unlock(&mm->unused_lock);
 369
 370         BUG_ON(mm->num_unused != 0);
 371 }
 372 EXPORT_SYMBOL(drm_mm_takedown);