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  *
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  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 <drm/drmP.h>
  45 #include <drm/drm_mm.h>
  46 #include <linux/slab.h>
  47 #include <linux/seq_file.h>
  48 #include <linux/export.h>
  49
  50 /**
  51  * DOC: Overview
  52  *
  53  * drm_mm provides a simple range allocator. The drivers are free to use the
  54  * resource allocator from the linux core if it suits them, the upside of drm_mm
  55  * is that it's in the DRM core. Which means that it's easier to extend for
  56  * some of the crazier special purpose needs of gpus.
  57  *
  58  * The main data struct is &drm_mm, allocations are tracked in &drm_mm_node.
  59  * Drivers are free to embed either of them into their own suitable
  60  * datastructures. drm_mm itself will not do any allocations of its own, so if
  61  * drivers choose not to embed nodes they need to still allocate them
  62  * themselves.
  63  *
  64  * The range allocator also supports reservation of preallocated blocks. This is
  65  * useful for taking over initial mode setting configurations from the firmware,
  66  * where an object needs to be created which exactly matches the firmware's
  67  * scanout target. As long as the range is still free it can be inserted anytime
  68  * after the allocator is initialized, which helps with avoiding looped
  69  * depencies in the driver load sequence.
  70  *
  71  * drm_mm maintains a stack of most recently freed holes, which of all
  72  * simplistic datastructures seems to be a fairly decent approach to clustering
  73  * allocations and avoiding too much fragmentation. This means free space
  74  * searches are O(num_holes). Given that all the fancy features drm_mm supports
  75  * something better would be fairly complex and since gfx thrashing is a fairly
  76  * steep cliff not a real concern. Removing a node again is O(1).
  77  *
  78  * drm_mm supports a few features: Alignment and range restrictions can be
  79  * supplied. Further more every &drm_mm_node has a color value (which is just an
  80  * opaqua unsigned long) which in conjunction with a driver callback can be used
  81  * to implement sophisticated placement restrictions. The i915 DRM driver uses
  82  * this to implement guard pages between incompatible caching domains in the
  83  * graphics TT.
  84  *
  85  * Two behaviors are supported for searching and allocating: bottom-up and top-down.
  86  * The default is bottom-up. Top-down allocation can be used if the memory area
  87  * has different restrictions, or just to reduce fragmentation.
  88  *
  89  * Finally iteration helpers to walk all nodes and all holes are provided as are
  90  * some basic allocator dumpers for debugging.
  91  */
  92
  93 static struct drm_mm_node *drm_mm_search_free_generic(const struct drm_mm *mm,
  94                                                 unsigned long size,
  95                                                 unsigned alignment,
  96                                                 unsigned long color,
  97                                                 enum drm_mm_search_flags flags);
  98 static struct drm_mm_node *drm_mm_search_free_in_range_generic(const struct drm_mm *mm,
  99                                                 unsigned long size,
 100                                                 unsigned alignment,
 101                                                 unsigned long color,
 102                                                 unsigned long start,
 103                                                 unsigned long end,
 104                                                 enum drm_mm_search_flags flags);
 105
 106 static void drm_mm_insert_helper(struct drm_mm_node *hole_node,
 107                                  struct drm_mm_node *node,
 108                                  unsigned long size, unsigned alignment,
 109                                  unsigned long color,
 110                                  enum drm_mm_allocator_flags flags)
 111 {
 112         struct drm_mm *mm = hole_node->mm;
 113         unsigned long hole_start = drm_mm_hole_node_start(hole_node);
 114         unsigned long hole_end = drm_mm_hole_node_end(hole_node);
 115         unsigned long adj_start = hole_start;
 116         unsigned long adj_end = hole_end;
 117
 118         BUG_ON(node->allocated);
 119
 120         if (mm->color_adjust)
 121                 mm->color_adjust(hole_node, color, &adj_start, &adj_end);
 122
 123         if (flags & DRM_MM_CREATE_TOP)
 124                 adj_start = adj_end - size;
 125
 126         if (alignment) {
 127                 unsigned tmp = adj_start % alignment;
 128                 if (tmp) {
 129                         if (flags & DRM_MM_CREATE_TOP)
 130                                 adj_start -= tmp;
 131                         else
 132                                 adj_start += alignment - tmp;
 133                 }
 134         }
 135
 136         BUG_ON(adj_start < hole_start);
 137         BUG_ON(adj_end > hole_end);
 138
 139         if (adj_start == hole_start) {
 140                 hole_node->hole_follows = 0;
 141                 list_del(&hole_node->hole_stack);
 142         }
 143
 144         node->start = adj_start;
 145         node->size = size;
 146         node->mm = mm;
 147         node->color = color;
 148         node->allocated = 1;
 149
 150         INIT_LIST_HEAD(&node->hole_stack);
 151         list_add(&node->node_list, &hole_node->node_list);
 152
 153         BUG_ON(node->start + node->size > adj_end);
 154
 155         node->hole_follows = 0;
 156         if (__drm_mm_hole_node_start(node) < hole_end) {
 157                 list_add(&node->hole_stack, &mm->hole_stack);
 158                 node->hole_follows = 1;
 159         }
 160 }
 161
 162 /**
 163  * drm_mm_reserve_node - insert an pre-initialized node
 164  * @mm: drm_mm allocator to insert @node into
 165  * @node: drm_mm_node to insert
 166  *
 167  * This functions inserts an already set-up drm_mm_node into the allocator,
 168  * meaning that start, size and color must be set by the caller. This is useful
 169  * to initialize the allocator with preallocated objects which must be set-up
 170  * before the range allocator can be set-up, e.g. when taking over a firmware
 171  * framebuffer.
 172  *
 173  * Returns:
 174  * 0 on success, -ENOSPC if there's no hole where @node is.
 175  */
 176 int drm_mm_reserve_node(struct drm_mm *mm, struct drm_mm_node *node)
 177 {
 178         struct drm_mm_node *hole;
 179         unsigned long end = node->start + node->size;
 180         unsigned long hole_start;
 181         unsigned long hole_end;
 182
 183         BUG_ON(node == NULL);
 184
 185         /* Find the relevant hole to add our node to */
 186         drm_mm_for_each_hole(hole, mm, hole_start, hole_end) {
 187                 if (hole_start > node->start || hole_end < end)
 188                         continue;
 189
 190                 node->mm = mm;
 191                 node->allocated = 1;
 192
 193                 INIT_LIST_HEAD(&node->hole_stack);
 194                 list_add(&node->node_list, &hole->node_list);
 195
 196                 if (node->start == hole_start) {
 197                         hole->hole_follows = 0;
 198                         list_del_init(&hole->hole_stack);
 199                 }
 200
 201                 node->hole_follows = 0;
 202                 if (end != hole_end) {
 203                         list_add(&node->hole_stack, &mm->hole_stack);
 204                         node->hole_follows = 1;
 205                 }
 206
 207                 return 0;
 208         }
 209
 210         WARN(1, "no hole found for node 0x%lx + 0x%lx\n",
 211              node->start, node->size);
 212         return -ENOSPC;
 213 }
 214 EXPORT_SYMBOL(drm_mm_reserve_node);
 215
 216 /**
 217  * drm_mm_insert_node_generic - search for space and insert @node
 218  * @mm: drm_mm to allocate from
 219  * @node: preallocate node to insert
 220  * @size: size of the allocation
 221  * @alignment: alignment of the allocation
 222  * @color: opaque tag value to use for this node
 223  * @sflags: flags to fine-tune the allocation search
 224  * @aflags: flags to fine-tune the allocation behavior
 225  *
 226  * The preallocated node must be cleared to 0.
 227  *
 228  * Returns:
 229  * 0 on success, -ENOSPC if there's no suitable hole.
 230  */
 231 int drm_mm_insert_node_generic(struct drm_mm *mm, struct drm_mm_node *node,
 232                                unsigned long size, unsigned alignment,
 233                                unsigned long color,
 234                                enum drm_mm_search_flags sflags,
 235                                enum drm_mm_allocator_flags aflags)
 236 {
 237         struct drm_mm_node *hole_node;
 238
 239         hole_node = drm_mm_search_free_generic(mm, size, alignment,
 240                                                color, sflags);
 241         if (!hole_node)
 242                 return -ENOSPC;
 243
 244         drm_mm_insert_helper(hole_node, node, size, alignment, color, aflags);
 245         return 0;
 246 }
 247 EXPORT_SYMBOL(drm_mm_insert_node_generic);
 248
 249 static void drm_mm_insert_helper_range(struct drm_mm_node *hole_node,
 250                                        struct drm_mm_node *node,
 251                                        unsigned long size, unsigned alignment,
 252                                        unsigned long color,
 253                                        unsigned long start, unsigned long end,
 254                                        enum drm_mm_allocator_flags flags)
 255 {
 256         struct drm_mm *mm = hole_node->mm;
 257         unsigned long hole_start = drm_mm_hole_node_start(hole_node);
 258         unsigned long hole_end = drm_mm_hole_node_end(hole_node);
 259         unsigned long adj_start = hole_start;
 260         unsigned long adj_end = hole_end;
 261
 262         BUG_ON(!hole_node->hole_follows || node->allocated);
 263
 264         if (adj_start < start)
 265                 adj_start = start;
 266         if (adj_end > end)
 267                 adj_end = end;
 268
 269         if (flags & DRM_MM_CREATE_TOP)
 270                 adj_start = adj_end - size;
 271
 272         if (mm->color_adjust)
 273                 mm->color_adjust(hole_node, color, &adj_start, &adj_end);
 274
 275         if (alignment) {
 276                 unsigned tmp = adj_start % alignment;
 277                 if (tmp) {
 278                         if (flags & DRM_MM_CREATE_TOP)
 279                                 adj_start -= tmp;
 280                         else
 281                                 adj_start += alignment - tmp;
 282                 }
 283         }
 284
 285         if (adj_start == hole_start) {
 286                 hole_node->hole_follows = 0;
 287                 list_del(&hole_node->hole_stack);
 288         }
 289
 290         node->start = adj_start;
 291         node->size = size;
 292         node->mm = mm;
 293         node->color = color;
 294         node->allocated = 1;
 295
 296         INIT_LIST_HEAD(&node->hole_stack);
 297         list_add(&node->node_list, &hole_node->node_list);
 298
 299         BUG_ON(node->start < start);
 300         BUG_ON(node->start < adj_start);
 301         BUG_ON(node->start + node->size > adj_end);
 302         BUG_ON(node->start + node->size > end);
 303
 304         node->hole_follows = 0;
 305         if (__drm_mm_hole_node_start(node) < hole_end) {
 306                 list_add(&node->hole_stack, &mm->hole_stack);
 307                 node->hole_follows = 1;
 308         }
 309 }
 310
 311 /**
 312  * drm_mm_insert_node_in_range_generic - ranged search for space and insert @node
 313  * @mm: drm_mm to allocate from
 314  * @node: preallocate node to insert
 315  * @size: size of the allocation
 316  * @alignment: alignment of the allocation
 317  * @color: opaque tag value to use for this node
 318  * @start: start of the allowed range for this node
 319  * @end: end of the allowed range for this node
 320  * @sflags: flags to fine-tune the allocation search
 321  * @aflags: flags to fine-tune the allocation behavior
 322  *
 323  * The preallocated node must be cleared to 0.
 324  *
 325  * Returns:
 326  * 0 on success, -ENOSPC if there's no suitable hole.
 327  */
 328 int drm_mm_insert_node_in_range_generic(struct drm_mm *mm, struct drm_mm_node *node,
 329                                         unsigned long size, unsigned alignment,
 330                                         unsigned long color,
 331                                         unsigned long start, unsigned long end,
 332                                         enum drm_mm_search_flags sflags,
 333                                         enum drm_mm_allocator_flags aflags)
 334 {
 335         struct drm_mm_node *hole_node;
 336
 337         hole_node = drm_mm_search_free_in_range_generic(mm,
 338                                                         size, alignment, color,
 339                                                         start, end, sflags);
 340         if (!hole_node)
 341                 return -ENOSPC;
 342
 343         drm_mm_insert_helper_range(hole_node, node,
 344                                    size, alignment, color,
 345                                    start, end, aflags);
 346         return 0;
 347 }
 348 EXPORT_SYMBOL(drm_mm_insert_node_in_range_generic);
 349
 350 /**
 351  * drm_mm_remove_node - Remove a memory node from the allocator.
 352  * @node: drm_mm_node to remove
 353  *
 354  * This just removes a node from its drm_mm allocator. The node does not need to
 355  * be cleared again before it can be re-inserted into this or any other drm_mm
 356  * allocator. It is a bug to call this function on a un-allocated node.
 357  */
 358 void drm_mm_remove_node(struct drm_mm_node *node)
 359 {
 360         struct drm_mm *mm = node->mm;
 361         struct drm_mm_node *prev_node;
 362
 363         if (WARN_ON(!node->allocated))
 364                 return;
 365
 366         BUG_ON(node->scanned_block || node->scanned_prev_free
 367                                    || node->scanned_next_free);
 368
 369         prev_node =
 370             list_entry(node->node_list.prev, struct drm_mm_node, node_list);
 371
 372         if (node->hole_follows) {
 373                 BUG_ON(__drm_mm_hole_node_start(node) ==
 374                        __drm_mm_hole_node_end(node));
 375                 list_del(&node->hole_stack);
 376         } else
 377                 BUG_ON(__drm_mm_hole_node_start(node) !=
 378                        __drm_mm_hole_node_end(node));
 379
 380
 381         if (!prev_node->hole_follows) {
 382                 prev_node->hole_follows = 1;
 383                 list_add(&prev_node->hole_stack, &mm->hole_stack);
 384         } else
 385                 list_move(&prev_node->hole_stack, &mm->hole_stack);
 386
 387         list_del(&node->node_list);
 388         node->allocated = 0;
 389 }
 390 EXPORT_SYMBOL(drm_mm_remove_node);
 391
 392 static int check_free_hole(unsigned long start, unsigned long end,
 393                            unsigned long size, unsigned alignment)
 394 {
 395         if (end - start < size)
 396                 return 0;
 397
 398         if (alignment) {
 399                 unsigned tmp = start % alignment;
 400                 if (tmp)
 401                         start += alignment - tmp;
 402         }
 403
 404         return end >= start + size;
 405 }
 406
 407 static struct drm_mm_node *drm_mm_search_free_generic(const struct drm_mm *mm,
 408                                                       unsigned long size,
 409                                                       unsigned alignment,
 410                                                       unsigned long color,
 411                                                       enum drm_mm_search_flags flags)
 412 {
 413         struct drm_mm_node *entry;
 414         struct drm_mm_node *best;
 415         unsigned long adj_start;
 416         unsigned long adj_end;
 417         unsigned long best_size;
 418
 419         BUG_ON(mm->scanned_blocks);
 420
 421         best = NULL;
 422         best_size = ~0UL;
 423
 424         __drm_mm_for_each_hole(entry, mm, adj_start, adj_end,
 425                                flags & DRM_MM_SEARCH_BELOW) {
 426                 unsigned long hole_size = adj_end - adj_start;
 427
 428                 if (mm->color_adjust) {
 429                         mm->color_adjust(entry, color, &adj_start, &adj_end);
 430                         if (adj_end <= adj_start)
 431                                 continue;
 432                 }
 433
 434                 if (!check_free_hole(adj_start, adj_end, size, alignment))
 435                         continue;
 436
 437                 if (!(flags & DRM_MM_SEARCH_BEST))
 438                         return entry;
 439
 440                 if (hole_size < best_size) {
 441                         best = entry;
 442                         best_size = hole_size;
 443                 }
 444         }
 445
 446         return best;
 447 }
 448
 449 static struct drm_mm_node *drm_mm_search_free_in_range_generic(const struct drm_mm *mm,
 450                                                         unsigned long size,
 451                                                         unsigned alignment,
 452                                                         unsigned long color,
 453                                                         unsigned long start,
 454                                                         unsigned long end,
 455                                                         enum drm_mm_search_flags flags)
 456 {
 457         struct drm_mm_node *entry;
 458         struct drm_mm_node *best;
 459         unsigned long adj_start;
 460         unsigned long adj_end;
 461         unsigned long best_size;
 462
 463         BUG_ON(mm->scanned_blocks);
 464
 465         best = NULL;
 466         best_size = ~0UL;
 467
 468         __drm_mm_for_each_hole(entry, mm, adj_start, adj_end,
 469                                flags & DRM_MM_SEARCH_BELOW) {
 470                 unsigned long hole_size = adj_end - adj_start;
 471
 472                 if (adj_start < start)
 473                         adj_start = start;
 474                 if (adj_end > end)
 475                         adj_end = end;
 476
 477                 if (mm->color_adjust) {
 478                         mm->color_adjust(entry, color, &adj_start, &adj_end);
 479                         if (adj_end <= adj_start)
 480                                 continue;
 481                 }
 482
 483                 if (!check_free_hole(adj_start, adj_end, size, alignment))
 484                         continue;
 485
 486                 if (!(flags & DRM_MM_SEARCH_BEST))
 487                         return entry;
 488
 489                 if (hole_size < best_size) {
 490                         best = entry;
 491                         best_size = hole_size;
 492                 }
 493         }
 494
 495         return best;
 496 }
 497
 498 /**
 499  * drm_mm_replace_node - move an allocation from @old to @new
 500  * @old: drm_mm_node to remove from the allocator
 501  * @new: drm_mm_node which should inherit @old's allocation
 502  *
 503  * This is useful for when drivers embed the drm_mm_node structure and hence
 504  * can't move allocations by reassigning pointers. It's a combination of remove
 505  * and insert with the guarantee that the allocation start will match.
 506  */
 507 void drm_mm_replace_node(struct drm_mm_node *old, struct drm_mm_node *new)
 508 {
 509         list_replace(&old->node_list, &new->node_list);
 510         list_replace(&old->hole_stack, &new->hole_stack);
 511         new->hole_follows = old->hole_follows;
 512         new->mm = old->mm;
 513         new->start = old->start;
 514         new->size = old->size;
 515         new->color = old->color;
 516
 517         old->allocated = 0;
 518         new->allocated = 1;
 519 }
 520 EXPORT_SYMBOL(drm_mm_replace_node);
 521
 522 /**
 523  * DOC: lru scan roaster
 524  *
 525  * Very often GPUs need to have continuous allocations for a given object. When
 526  * evicting objects to make space for a new one it is therefore not most
 527  * efficient when we simply start to select all objects from the tail of an LRU
 528  * until there's a suitable hole: Especially for big objects or nodes that
 529  * otherwise have special allocation constraints there's a good chance we evict
 530  * lots of (smaller) objects unecessarily.
 531  *
 532  * The DRM range allocator supports this use-case through the scanning
 533  * interfaces. First a scan operation needs to be initialized with
 534  * drm_mm_init_scan() or drm_mm_init_scan_with_range(). The the driver adds
 535  * objects to the roaster (probably by walking an LRU list, but this can be
 536  * freely implemented) until a suitable hole is found or there's no further
 537  * evitable object.
 538  *
 539  * The the driver must walk through all objects again in exactly the reverse
 540  * order to restore the allocator state. Note that while the allocator is used
 541  * in the scan mode no other operation is allowed.
 542  *
 543  * Finally the driver evicts all objects selected in the scan. Adding and
 544  * removing an object is O(1), and since freeing a node is also O(1) the overall
 545  * complexity is O(scanned_objects). So like the free stack which needs to be
 546  * walked before a scan operation even begins this is linear in the number of
 547  * objects. It doesn't seem to hurt badly.
 548  */
 549
 550 /**
 551  * drm_mm_init_scan - initialize lru scanning
 552  * @mm: drm_mm to scan
 553  * @size: size of the allocation
 554  * @alignment: alignment of the allocation
 555  * @color: opaque tag value to use for the allocation
 556  *
 557  * This simply sets up the scanning routines with the parameters for the desired
 558  * hole. Note that there's no need to specify allocation flags, since they only
 559  * change the place a node is allocated from within a suitable hole.
 560  *
 561  * Warning:
 562  * As long as the scan list is non-empty, no other operations than
 563  * adding/removing nodes to/from the scan list are allowed.
 564  */
 565 void drm_mm_init_scan(struct drm_mm *mm,
 566                       unsigned long size,
 567                       unsigned alignment,
 568                       unsigned long color)
 569 {
 570         mm->scan_color = color;
 571         mm->scan_alignment = alignment;
 572         mm->scan_size = size;
 573         mm->scanned_blocks = 0;
 574         mm->scan_hit_start = 0;
 575         mm->scan_hit_end = 0;
 576         mm->scan_check_range = 0;
 577         mm->prev_scanned_node = NULL;
 578 }
 579 EXPORT_SYMBOL(drm_mm_init_scan);
 580
 581 /**
 582  * drm_mm_init_scan - initialize range-restricted lru scanning
 583  * @mm: drm_mm to scan
 584  * @size: size of the allocation
 585  * @alignment: alignment of the allocation
 586  * @color: opaque tag value to use for the allocation
 587  * @start: start of the allowed range for the allocation
 588  * @end: end of the allowed range for the allocation
 589  *
 590  * This simply sets up the scanning routines with the parameters for the desired
 591  * hole. Note that there's no need to specify allocation flags, since they only
 592  * change the place a node is allocated from within a suitable hole.
 593  *
 594  * Warning:
 595  * As long as the scan list is non-empty, no other operations than
 596  * adding/removing nodes to/from the scan list are allowed.
 597  */
 598 void drm_mm_init_scan_with_range(struct drm_mm *mm,
 599                                  unsigned long size,
 600                                  unsigned alignment,
 601                                  unsigned long color,
 602                                  unsigned long start,
 603                                  unsigned long end)
 604 {
 605         mm->scan_color = color;
 606         mm->scan_alignment = alignment;
 607         mm->scan_size = size;
 608         mm->scanned_blocks = 0;
 609         mm->scan_hit_start = 0;
 610         mm->scan_hit_end = 0;
 611         mm->scan_start = start;
 612         mm->scan_end = end;
 613         mm->scan_check_range = 1;
 614         mm->prev_scanned_node = NULL;
 615 }
 616 EXPORT_SYMBOL(drm_mm_init_scan_with_range);
 617
 618 /**
 619  * drm_mm_scan_add_block - add a node to the scan list
 620  * @node: drm_mm_node to add
 621  *
 622  * Add a node to the scan list that might be freed to make space for the desired
 623  * hole.
 624  *
 625  * Returns:
 626  * True if a hole has been found, false otherwise.
 627  */
 628 bool drm_mm_scan_add_block(struct drm_mm_node *node)
 629 {
 630         struct drm_mm *mm = node->mm;
 631         struct drm_mm_node *prev_node;
 632         unsigned long hole_start, hole_end;
 633         unsigned long adj_start, adj_end;
 634
 635         mm->scanned_blocks++;
 636
 637         BUG_ON(node->scanned_block);
 638         node->scanned_block = 1;
 639
 640         prev_node = list_entry(node->node_list.prev, struct drm_mm_node,
 641                                node_list);
 642
 643         node->scanned_preceeds_hole = prev_node->hole_follows;
 644         prev_node->hole_follows = 1;
 645         list_del(&node->node_list);
 646         node->node_list.prev = &prev_node->node_list;
 647         node->node_list.next = &mm->prev_scanned_node->node_list;
 648         mm->prev_scanned_node = node;
 649
 650         adj_start = hole_start = drm_mm_hole_node_start(prev_node);
 651         adj_end = hole_end = drm_mm_hole_node_end(prev_node);
 652
 653         if (mm->scan_check_range) {
 654                 if (adj_start < mm->scan_start)
 655                         adj_start = mm->scan_start;
 656                 if (adj_end > mm->scan_end)
 657                         adj_end = mm->scan_end;
 658         }
 659
 660         if (mm->color_adjust)
 661                 mm->color_adjust(prev_node, mm->scan_color,
 662                                  &adj_start, &adj_end);
 663
 664         if (check_free_hole(adj_start, adj_end,
 665                             mm->scan_size, mm->scan_alignment)) {
 666                 mm->scan_hit_start = hole_start;
 667                 mm->scan_hit_end = hole_end;
 668                 return true;
 669         }
 670
 671         return false;
 672 }
 673 EXPORT_SYMBOL(drm_mm_scan_add_block);
 674
 675 /**
 676  * drm_mm_scan_remove_block - remove a node from the scan list
 677  * @node: drm_mm_node to remove
 678  *
 679  * Nodes _must_ be removed in the exact same order from the scan list as they
 680  * have been added, otherwise the internal state of the memory manager will be
 681  * corrupted.
 682  *
 683  * When the scan list is empty, the selected memory nodes can be freed. An
 684  * immediately following drm_mm_search_free with !DRM_MM_SEARCH_BEST will then
 685  * return the just freed block (because its at the top of the free_stack list).
 686  *
 687  * Returns:
 688  * True if this block should be evicted, false otherwise. Will always
 689  * return false when no hole has been found.
 690  */
 691 bool drm_mm_scan_remove_block(struct drm_mm_node *node)
 692 {
 693         struct drm_mm *mm = node->mm;
 694         struct drm_mm_node *prev_node;
 695
 696         mm->scanned_blocks--;
 697
 698         BUG_ON(!node->scanned_block);
 699         node->scanned_block = 0;
 700
 701         prev_node = list_entry(node->node_list.prev, struct drm_mm_node,
 702                                node_list);
 703
 704         prev_node->hole_follows = node->scanned_preceeds_hole;
 705         list_add(&node->node_list, &prev_node->node_list);
 706
 707          return (drm_mm_hole_node_end(node) > mm->scan_hit_start &&
 708                  node->start < mm->scan_hit_end);
 709 }
 710 EXPORT_SYMBOL(drm_mm_scan_remove_block);
 711
 712 /**
 713  * drm_mm_clean - checks whether an allocator is clean
 714  * @mm: drm_mm allocator to check
 715  *
 716  * Returns:
 717  * True if the allocator is completely free, false if there's still a node
 718  * allocated in it.
 719  */
 720 bool drm_mm_clean(struct drm_mm * mm)
 721 {
 722         struct list_head *head = &mm->head_node.node_list;
 723
 724         return (head->next->next == head);
 725 }
 726 EXPORT_SYMBOL(drm_mm_clean);
 727
 728 /**
 729  * drm_mm_init - initialize a drm-mm allocator
 730  * @mm: the drm_mm structure to initialize
 731  * @start: start of the range managed by @mm
 732  * @size: end of the range managed by @mm
 733  *
 734  * Note that @mm must be cleared to 0 before calling this function.
 735  */
 736 void drm_mm_init(struct drm_mm * mm, unsigned long start, unsigned long size)
 737 {
 738         INIT_LIST_HEAD(&mm->hole_stack);
 739         mm->scanned_blocks = 0;
 740
 741         /* Clever trick to avoid a special case in the free hole tracking. */
 742         INIT_LIST_HEAD(&mm->head_node.node_list);
 743         INIT_LIST_HEAD(&mm->head_node.hole_stack);
 744         mm->head_node.hole_follows = 1;
 745         mm->head_node.scanned_block = 0;
 746         mm->head_node.scanned_prev_free = 0;
 747         mm->head_node.scanned_next_free = 0;
 748         mm->head_node.mm = mm;
 749         mm->head_node.start = start + size;
 750         mm->head_node.size = start - mm->head_node.start;
 751         list_add_tail(&mm->head_node.hole_stack, &mm->hole_stack);
 752
 753         mm->color_adjust = NULL;
 754 }
 755 EXPORT_SYMBOL(drm_mm_init);
 756
 757 /**
 758  * drm_mm_takedown - clean up a drm_mm allocator
 759  * @mm: drm_mm allocator to clean up
 760  *
 761  * Note that it is a bug to call this function on an allocator which is not
 762  * clean.
 763  */
 764 void drm_mm_takedown(struct drm_mm * mm)
 765 {
 766         WARN(!list_empty(&mm->head_node.node_list),
 767              "Memory manager not clean during takedown.\n");
 768 }
 769 EXPORT_SYMBOL(drm_mm_takedown);
 770
 771 static unsigned long drm_mm_debug_hole(struct drm_mm_node *entry,
 772                                        const char *prefix)
 773 {
 774         unsigned long hole_start, hole_end, hole_size;
 775
 776         if (entry->hole_follows) {
 777                 hole_start = drm_mm_hole_node_start(entry);
 778                 hole_end = drm_mm_hole_node_end(entry);
 779                 hole_size = hole_end - hole_start;
 780                 printk(KERN_DEBUG "%s 0x%08lx-0x%08lx: %8lu: free\n",
 781                         prefix, hole_start, hole_end,
 782                         hole_size);
 783                 return hole_size;
 784         }
 785
 786         return 0;
 787 }
 788
 789 /**
 790  * drm_mm_debug_table - dump allocator state to dmesg
 791  * @mm: drm_mm allocator to dump
 792  * @prefix: prefix to use for dumping to dmesg
 793  */
 794 void drm_mm_debug_table(struct drm_mm *mm, const char *prefix)
 795 {
 796         struct drm_mm_node *entry;
 797         unsigned long total_used = 0, total_free = 0, total = 0;
 798
 799         total_free += drm_mm_debug_hole(&mm->head_node, prefix);
 800
 801         drm_mm_for_each_node(entry, mm) {
 802                 printk(KERN_DEBUG "%s 0x%08lx-0x%08lx: %8lu: used\n",
 803                         prefix, entry->start, entry->start + entry->size,
 804                         entry->size);
 805                 total_used += entry->size;
 806                 total_free += drm_mm_debug_hole(entry, prefix);
 807         }
 808         total = total_free + total_used;
 809
 810         printk(KERN_DEBUG "%s total: %lu, used %lu free %lu\n", prefix, total,
 811                 total_used, total_free);
 812 }
 813 EXPORT_SYMBOL(drm_mm_debug_table);
 814
 815 #if defined(CONFIG_DEBUG_FS)
 816 static unsigned long drm_mm_dump_hole(struct seq_file *m, struct drm_mm_node *entry)
 817 {
 818         unsigned long hole_start, hole_end, hole_size;
 819
 820         if (entry->hole_follows) {
 821                 hole_start = drm_mm_hole_node_start(entry);
 822                 hole_end = drm_mm_hole_node_end(entry);
 823                 hole_size = hole_end - hole_start;
 824                 seq_printf(m, "0x%08lx-0x%08lx: 0x%08lx: free\n",
 825                                 hole_start, hole_end, hole_size);
 826                 return hole_size;
 827         }
 828
 829         return 0;
 830 }
 831
 832 /**
 833  * drm_mm_dump_table - dump allocator state to a seq_file
 834  * @m: seq_file to dump to
 835  * @mm: drm_mm allocator to dump
 836  */
 837 int drm_mm_dump_table(struct seq_file *m, struct drm_mm *mm)
 838 {
 839         struct drm_mm_node *entry;
 840         unsigned long total_used = 0, total_free = 0, total = 0;
 841
 842         total_free += drm_mm_dump_hole(m, &mm->head_node);
 843
 844         drm_mm_for_each_node(entry, mm) {
 845                 seq_printf(m, "0x%08lx-0x%08lx: 0x%08lx: used\n",
 846                                 entry->start, entry->start + entry->size,
 847                                 entry->size);
 848                 total_used += entry->size;
 849                 total_free += drm_mm_dump_hole(m, entry);
 850         }
 851         total = total_free + total_used;
 852
 853         seq_printf(m, "total: %lu, used %lu free %lu\n", total, total_used, total_free);
 854         return 0;
 855 }
 856 EXPORT_SYMBOL(drm_mm_dump_table);
 857 #endif