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 <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                 if (mm->color_adjust) {
 427                         mm->color_adjust(entry, color, &adj_start, &adj_end);
 428                         if (adj_end <= adj_start)
 429                                 continue;
 430                 }
 431
 432                 if (!check_free_hole(adj_start, adj_end, size, alignment))
 433                         continue;
 434
 435                 if (!(flags & DRM_MM_SEARCH_BEST))
 436                         return entry;
 437
 438                 if (entry->size < best_size) {
 439                         best = entry;
 440                         best_size = entry->size;
 441                 }
 442         }
 443
 444         return best;
 445 }
 446
 447 static struct drm_mm_node *drm_mm_search_free_in_range_generic(const struct drm_mm *mm,
 448                                                         unsigned long size,
 449                                                         unsigned alignment,
 450                                                         unsigned long color,
 451                                                         unsigned long start,
 452                                                         unsigned long end,
 453                                                         enum drm_mm_search_flags flags)
 454 {
 455         struct drm_mm_node *entry;
 456         struct drm_mm_node *best;
 457         unsigned long adj_start;
 458         unsigned long adj_end;
 459         unsigned long best_size;
 460
 461         BUG_ON(mm->scanned_blocks);
 462
 463         best = NULL;
 464         best_size = ~0UL;
 465
 466         __drm_mm_for_each_hole(entry, mm, adj_start, adj_end,
 467                                flags & DRM_MM_SEARCH_BELOW) {
 468                 if (adj_start < start)
 469                         adj_start = start;
 470                 if (adj_end > end)
 471                         adj_end = end;
 472
 473                 if (mm->color_adjust) {
 474                         mm->color_adjust(entry, color, &adj_start, &adj_end);
 475                         if (adj_end <= adj_start)
 476                                 continue;
 477                 }
 478
 479                 if (!check_free_hole(adj_start, adj_end, size, alignment))
 480                         continue;
 481
 482                 if (!(flags & DRM_MM_SEARCH_BEST))
 483                         return entry;
 484
 485                 if (entry->size < best_size) {
 486                         best = entry;
 487                         best_size = entry->size;
 488                 }
 489         }
 490
 491         return best;
 492 }
 493
 494 /**
 495  * drm_mm_replace_node - move an allocation from @old to @new
 496  * @old: drm_mm_node to remove from the allocator
 497  * @new: drm_mm_node which should inherit @old's allocation
 498  *
 499  * This is useful for when drivers embed the drm_mm_node structure and hence
 500  * can't move allocations by reassigning pointers. It's a combination of remove
 501  * and insert with the guarantee that the allocation start will match.
 502  */
 503 void drm_mm_replace_node(struct drm_mm_node *old, struct drm_mm_node *new)
 504 {
 505         list_replace(&old->node_list, &new->node_list);
 506         list_replace(&old->hole_stack, &new->hole_stack);
 507         new->hole_follows = old->hole_follows;
 508         new->mm = old->mm;
 509         new->start = old->start;
 510         new->size = old->size;
 511         new->color = old->color;
 512
 513         old->allocated = 0;
 514         new->allocated = 1;
 515 }
 516 EXPORT_SYMBOL(drm_mm_replace_node);
 517
 518 /**
 519  * DOC: lru scan roaster
 520  *
 521  * Very often GPUs need to have continuous allocations for a given object. When
 522  * evicting objects to make space for a new one it is therefore not most
 523  * efficient when we simply start to select all objects from the tail of an LRU
 524  * until there's a suitable hole: Especially for big objects or nodes that
 525  * otherwise have special allocation constraints there's a good chance we evict
 526  * lots of (smaller) objects unecessarily.
 527  *
 528  * The DRM range allocator supports this use-case through the scanning
 529  * interfaces. First a scan operation needs to be initialized with
 530  * drm_mm_init_scan() or drm_mm_init_scan_with_range(). The the driver adds
 531  * objects to the roaster (probably by walking an LRU list, but this can be
 532  * freely implemented) until a suitable hole is found or there's no further
 533  * evitable object.
 534  *
 535  * The the driver must walk through all objects again in exactly the reverse
 536  * order to restore the allocator state. Note that while the allocator is used
 537  * in the scan mode no other operation is allowed.
 538  *
 539  * Finally the driver evicts all objects selected in the scan. Adding and
 540  * removing an object is O(1), and since freeing a node is also O(1) the overall
 541  * complexity is O(scanned_objects). So like the free stack which needs to be
 542  * walked before a scan operation even begins this is linear in the number of
 543  * objects. It doesn't seem to hurt badly.
 544  */
 545
 546 /**
 547  * drm_mm_init_scan - initialize lru scanning
 548  * @mm: drm_mm to scan
 549  * @size: size of the allocation
 550  * @alignment: alignment of the allocation
 551  * @color: opaque tag value to use for the allocation
 552  *
 553  * This simply sets up the scanning routines with the parameters for the desired
 554  * hole. Note that there's no need to specify allocation flags, since they only
 555  * change the place a node is allocated from within a suitable hole.
 556  *
 557  * Warning:
 558  * As long as the scan list is non-empty, no other operations than
 559  * adding/removing nodes to/from the scan list are allowed.
 560  */
 561 void drm_mm_init_scan(struct drm_mm *mm,
 562                       unsigned long size,
 563                       unsigned alignment,
 564                       unsigned long color)
 565 {
 566         mm->scan_color = color;
 567         mm->scan_alignment = alignment;
 568         mm->scan_size = size;
 569         mm->scanned_blocks = 0;
 570         mm->scan_hit_start = 0;
 571         mm->scan_hit_end = 0;
 572         mm->scan_check_range = 0;
 573         mm->prev_scanned_node = NULL;
 574 }
 575 EXPORT_SYMBOL(drm_mm_init_scan);
 576
 577 /**
 578  * drm_mm_init_scan - initialize range-restricted lru scanning
 579  * @mm: drm_mm to scan
 580  * @size: size of the allocation
 581  * @alignment: alignment of the allocation
 582  * @color: opaque tag value to use for the allocation
 583  * @start: start of the allowed range for the allocation
 584  * @end: end of the allowed range for the allocation
 585  *
 586  * This simply sets up the scanning routines with the parameters for the desired
 587  * hole. Note that there's no need to specify allocation flags, since they only
 588  * change the place a node is allocated from within a suitable hole.
 589  *
 590  * Warning:
 591  * As long as the scan list is non-empty, no other operations than
 592  * adding/removing nodes to/from the scan list are allowed.
 593  */
 594 void drm_mm_init_scan_with_range(struct drm_mm *mm,
 595                                  unsigned long size,
 596                                  unsigned alignment,
 597                                  unsigned long color,
 598                                  unsigned long start,
 599                                  unsigned long end)
 600 {
 601         mm->scan_color = color;
 602         mm->scan_alignment = alignment;
 603         mm->scan_size = size;
 604         mm->scanned_blocks = 0;
 605         mm->scan_hit_start = 0;
 606         mm->scan_hit_end = 0;
 607         mm->scan_start = start;
 608         mm->scan_end = end;
 609         mm->scan_check_range = 1;
 610         mm->prev_scanned_node = NULL;
 611 }
 612 EXPORT_SYMBOL(drm_mm_init_scan_with_range);
 613
 614 /**
 615  * drm_mm_scan_add_block - add a node to the scan list
 616  * @node: drm_mm_node to add
 617  *
 618  * Add a node to the scan list that might be freed to make space for the desired
 619  * hole.
 620  *
 621  * Returns:
 622  * True if a hole has been found, false otherwise.
 623  */
 624 bool drm_mm_scan_add_block(struct drm_mm_node *node)
 625 {
 626         struct drm_mm *mm = node->mm;
 627         struct drm_mm_node *prev_node;
 628         unsigned long hole_start, hole_end;
 629         unsigned long adj_start, adj_end;
 630
 631         mm->scanned_blocks++;
 632
 633         BUG_ON(node->scanned_block);
 634         node->scanned_block = 1;
 635
 636         prev_node = list_entry(node->node_list.prev, struct drm_mm_node,
 637                                node_list);
 638
 639         node->scanned_preceeds_hole = prev_node->hole_follows;
 640         prev_node->hole_follows = 1;
 641         list_del(&node->node_list);
 642         node->node_list.prev = &prev_node->node_list;
 643         node->node_list.next = &mm->prev_scanned_node->node_list;
 644         mm->prev_scanned_node = node;
 645
 646         adj_start = hole_start = drm_mm_hole_node_start(prev_node);
 647         adj_end = hole_end = drm_mm_hole_node_end(prev_node);
 648
 649         if (mm->scan_check_range) {
 650                 if (adj_start < mm->scan_start)
 651                         adj_start = mm->scan_start;
 652                 if (adj_end > mm->scan_end)
 653                         adj_end = mm->scan_end;
 654         }
 655
 656         if (mm->color_adjust)
 657                 mm->color_adjust(prev_node, mm->scan_color,
 658                                  &adj_start, &adj_end);
 659
 660         if (check_free_hole(adj_start, adj_end,
 661                             mm->scan_size, mm->scan_alignment)) {
 662                 mm->scan_hit_start = hole_start;
 663                 mm->scan_hit_end = hole_end;
 664                 return true;
 665         }
 666
 667         return false;
 668 }
 669 EXPORT_SYMBOL(drm_mm_scan_add_block);
 670
 671 /**
 672  * drm_mm_scan_remove_block - remove a node from the scan list
 673  * @node: drm_mm_node to remove
 674  *
 675  * Nodes _must_ be removed in the exact same order from the scan list as they
 676  * have been added, otherwise the internal state of the memory manager will be
 677  * corrupted.
 678  *
 679  * When the scan list is empty, the selected memory nodes can be freed. An
 680  * immediately following drm_mm_search_free with !DRM_MM_SEARCH_BEST will then
 681  * return the just freed block (because its at the top of the free_stack list).
 682  *
 683  * Returns:
 684  * True if this block should be evicted, false otherwise. Will always
 685  * return false when no hole has been found.
 686  */
 687 bool drm_mm_scan_remove_block(struct drm_mm_node *node)
 688 {
 689         struct drm_mm *mm = node->mm;
 690         struct drm_mm_node *prev_node;
 691
 692         mm->scanned_blocks--;
 693
 694         BUG_ON(!node->scanned_block);
 695         node->scanned_block = 0;
 696
 697         prev_node = list_entry(node->node_list.prev, struct drm_mm_node,
 698                                node_list);
 699
 700         prev_node->hole_follows = node->scanned_preceeds_hole;
 701         list_add(&node->node_list, &prev_node->node_list);
 702
 703          return (drm_mm_hole_node_end(node) > mm->scan_hit_start &&
 704                  node->start < mm->scan_hit_end);
 705 }
 706 EXPORT_SYMBOL(drm_mm_scan_remove_block);
 707
 708 /**
 709  * drm_mm_clean - checks whether an allocator is clean
 710  * @mm: drm_mm allocator to check
 711  *
 712  * Returns:
 713  * True if the allocator is completely free, false if there's still a node
 714  * allocated in it.
 715  */
 716 bool drm_mm_clean(struct drm_mm * mm)
 717 {
 718         struct list_head *head = &mm->head_node.node_list;
 719
 720         return (head->next->next == head);
 721 }
 722 EXPORT_SYMBOL(drm_mm_clean);
 723
 724 /**
 725  * drm_mm_init - initialize a drm-mm allocator
 726  * @mm: the drm_mm structure to initialize
 727  * @start: start of the range managed by @mm
 728  * @size: end of the range managed by @mm
 729  *
 730  * Note that @mm must be cleared to 0 before calling this function.
 731  */
 732 void drm_mm_init(struct drm_mm * mm, unsigned long start, unsigned long size)
 733 {
 734         INIT_LIST_HEAD(&mm->hole_stack);
 735         mm->scanned_blocks = 0;
 736
 737         /* Clever trick to avoid a special case in the free hole tracking. */
 738         INIT_LIST_HEAD(&mm->head_node.node_list);
 739         INIT_LIST_HEAD(&mm->head_node.hole_stack);
 740         mm->head_node.hole_follows = 1;
 741         mm->head_node.scanned_block = 0;
 742         mm->head_node.scanned_prev_free = 0;
 743         mm->head_node.scanned_next_free = 0;
 744         mm->head_node.mm = mm;
 745         mm->head_node.start = start + size;
 746         mm->head_node.size = start - mm->head_node.start;
 747         list_add_tail(&mm->head_node.hole_stack, &mm->hole_stack);
 748
 749         mm->color_adjust = NULL;
 750 }
 751 EXPORT_SYMBOL(drm_mm_init);
 752
 753 /**
 754  * drm_mm_takedown - clean up a drm_mm allocator
 755  * @mm: drm_mm allocator to clean up
 756  *
 757  * Note that it is a bug to call this function on an allocator which is not
 758  * clean.
 759  */
 760 void drm_mm_takedown(struct drm_mm * mm)
 761 {
 762         WARN(!list_empty(&mm->head_node.node_list),
 763              "Memory manager not clean during takedown.\n");
 764 }
 765 EXPORT_SYMBOL(drm_mm_takedown);
 766
 767 static unsigned long drm_mm_debug_hole(struct drm_mm_node *entry,
 768                                        const char *prefix)
 769 {
 770         unsigned long hole_start, hole_end, hole_size;
 771
 772         if (entry->hole_follows) {
 773                 hole_start = drm_mm_hole_node_start(entry);
 774                 hole_end = drm_mm_hole_node_end(entry);
 775                 hole_size = hole_end - hole_start;
 776                 printk(KERN_DEBUG "%s 0x%08lx-0x%08lx: %8lu: free\n",
 777                         prefix, hole_start, hole_end,
 778                         hole_size);
 779                 return hole_size;
 780         }
 781
 782         return 0;
 783 }
 784
 785 /**
 786  * drm_mm_debug_table - dump allocator state to dmesg
 787  * @mm: drm_mm allocator to dump
 788  * @prefix: prefix to use for dumping to dmesg
 789  */
 790 void drm_mm_debug_table(struct drm_mm *mm, const char *prefix)
 791 {
 792         struct drm_mm_node *entry;
 793         unsigned long total_used = 0, total_free = 0, total = 0;
 794
 795         total_free += drm_mm_debug_hole(&mm->head_node, prefix);
 796
 797         drm_mm_for_each_node(entry, mm) {
 798                 printk(KERN_DEBUG "%s 0x%08lx-0x%08lx: %8lu: used\n",
 799                         prefix, entry->start, entry->start + entry->size,
 800                         entry->size);
 801                 total_used += entry->size;
 802                 total_free += drm_mm_debug_hole(entry, prefix);
 803         }
 804         total = total_free + total_used;
 805
 806         printk(KERN_DEBUG "%s total: %lu, used %lu free %lu\n", prefix, total,
 807                 total_used, total_free);
 808 }
 809 EXPORT_SYMBOL(drm_mm_debug_table);
 810
 811 #if defined(CONFIG_DEBUG_FS)
 812 static unsigned long drm_mm_dump_hole(struct seq_file *m, struct drm_mm_node *entry)
 813 {
 814         unsigned long hole_start, hole_end, hole_size;
 815
 816         if (entry->hole_follows) {
 817                 hole_start = drm_mm_hole_node_start(entry);
 818                 hole_end = drm_mm_hole_node_end(entry);
 819                 hole_size = hole_end - hole_start;
 820                 seq_printf(m, "0x%08lx-0x%08lx: 0x%08lx: free\n",
 821                                 hole_start, hole_end, hole_size);
 822                 return hole_size;
 823         }
 824
 825         return 0;
 826 }
 827
 828 /**
 829  * drm_mm_dump_table - dump allocator state to a seq_file
 830  * @m: seq_file to dump to
 831  * @mm: drm_mm allocator to dump
 832  */
 833 int drm_mm_dump_table(struct seq_file *m, struct drm_mm *mm)
 834 {
 835         struct drm_mm_node *entry;
 836         unsigned long total_used = 0, total_free = 0, total = 0;
 837
 838         total_free += drm_mm_dump_hole(m, &mm->head_node);
 839
 840         drm_mm_for_each_node(entry, mm) {
 841                 seq_printf(m, "0x%08lx-0x%08lx: 0x%08lx: used\n",
 842                                 entry->start, entry->start + entry->size,
 843                                 entry->size);
 844                 total_used += entry->size;
 845                 total_free += drm_mm_dump_hole(m, entry);
 846         }
 847         total = total_free + total_used;
 848
 849         seq_printf(m, "total: %lu, used %lu free %lu\n", total, total_used, total_free);
 850         return 0;
 851 }
 852 EXPORT_SYMBOL(drm_mm_dump_table);
 853 #endif