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                                                 u64 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                                                 u64 size,
 100                                                 unsigned alignment,
 101                                                 unsigned long color,
 102                                                 u64 start,
 103                                                 u64 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                                  u64 size, unsigned alignment,
 109                                  unsigned long color,
 110                                  enum drm_mm_allocator_flags flags)
 111 {
 112         struct drm_mm *mm = hole_node->mm;
 113         u64 hole_start = drm_mm_hole_node_start(hole_node);
 114         u64 hole_end = drm_mm_hole_node_end(hole_node);
 115         u64 adj_start = hole_start;
 116         u64 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                 u64 tmp = adj_start;
 128                 unsigned rem;
 129
 130                 rem = do_div(tmp, alignment);
 131                 if (rem) {
 132                         if (flags & DRM_MM_CREATE_TOP)
 133                                 adj_start -= rem;
 134                         else
 135                                 adj_start += alignment - rem;
 136                 }
 137         }
 138
 139         BUG_ON(adj_start < hole_start);
 140         BUG_ON(adj_end > hole_end);
 141
 142         if (adj_start == hole_start) {
 143                 hole_node->hole_follows = 0;
 144                 list_del(&hole_node->hole_stack);
 145         }
 146
 147         node->start = adj_start;
 148         node->size = size;
 149         node->mm = mm;
 150         node->color = color;
 151         node->allocated = 1;
 152
 153         INIT_LIST_HEAD(&node->hole_stack);
 154         list_add(&node->node_list, &hole_node->node_list);
 155
 156         BUG_ON(node->start + node->size > adj_end);
 157
 158         node->hole_follows = 0;
 159         if (__drm_mm_hole_node_start(node) < hole_end) {
 160                 list_add(&node->hole_stack, &mm->hole_stack);
 161                 node->hole_follows = 1;
 162         }
 163 }
 164
 165 /**
 166  * drm_mm_reserve_node - insert an pre-initialized node
 167  * @mm: drm_mm allocator to insert @node into
 168  * @node: drm_mm_node to insert
 169  *
 170  * This functions inserts an already set-up drm_mm_node into the allocator,
 171  * meaning that start, size and color must be set by the caller. This is useful
 172  * to initialize the allocator with preallocated objects which must be set-up
 173  * before the range allocator can be set-up, e.g. when taking over a firmware
 174  * framebuffer.
 175  *
 176  * Returns:
 177  * 0 on success, -ENOSPC if there's no hole where @node is.
 178  */
 179 int drm_mm_reserve_node(struct drm_mm *mm, struct drm_mm_node *node)
 180 {
 181         struct drm_mm_node *hole;
 182         u64 end = node->start + node->size;
 183         u64 hole_start;
 184         u64 hole_end;
 185
 186         BUG_ON(node == NULL);
 187
 188         /* Find the relevant hole to add our node to */
 189         drm_mm_for_each_hole(hole, mm, hole_start, hole_end) {
 190                 if (hole_start > node->start || hole_end < end)
 191                         continue;
 192
 193                 node->mm = mm;
 194                 node->allocated = 1;
 195
 196                 INIT_LIST_HEAD(&node->hole_stack);
 197                 list_add(&node->node_list, &hole->node_list);
 198
 199                 if (node->start == hole_start) {
 200                         hole->hole_follows = 0;
 201                         list_del_init(&hole->hole_stack);
 202                 }
 203
 204                 node->hole_follows = 0;
 205                 if (end != hole_end) {
 206                         list_add(&node->hole_stack, &mm->hole_stack);
 207                         node->hole_follows = 1;
 208                 }
 209
 210                 return 0;
 211         }
 212
 213         return -ENOSPC;
 214 }
 215 EXPORT_SYMBOL(drm_mm_reserve_node);
 216
 217 /**
 218  * drm_mm_insert_node_generic - search for space and insert @node
 219  * @mm: drm_mm to allocate from
 220  * @node: preallocate node to insert
 221  * @size: size of the allocation
 222  * @alignment: alignment of the allocation
 223  * @color: opaque tag value to use for this node
 224  * @sflags: flags to fine-tune the allocation search
 225  * @aflags: flags to fine-tune the allocation behavior
 226  *
 227  * The preallocated node must be cleared to 0.
 228  *
 229  * Returns:
 230  * 0 on success, -ENOSPC if there's no suitable hole.
 231  */
 232 int drm_mm_insert_node_generic(struct drm_mm *mm, struct drm_mm_node *node,
 233                                u64 size, unsigned alignment,
 234                                unsigned long color,
 235                                enum drm_mm_search_flags sflags,
 236                                enum drm_mm_allocator_flags aflags)
 237 {
 238         struct drm_mm_node *hole_node;
 239
 240         hole_node = drm_mm_search_free_generic(mm, size, alignment,
 241                                                color, sflags);
 242         if (!hole_node)
 243                 return -ENOSPC;
 244
 245         drm_mm_insert_helper(hole_node, node, size, alignment, color, aflags);
 246         return 0;
 247 }
 248 EXPORT_SYMBOL(drm_mm_insert_node_generic);
 249
 250 static void drm_mm_insert_helper_range(struct drm_mm_node *hole_node,
 251                                        struct drm_mm_node *node,
 252                                        u64 size, unsigned alignment,
 253                                        unsigned long color,
 254                                        u64 start, u64 end,
 255                                        enum drm_mm_allocator_flags flags)
 256 {
 257         struct drm_mm *mm = hole_node->mm;
 258         u64 hole_start = drm_mm_hole_node_start(hole_node);
 259         u64 hole_end = drm_mm_hole_node_end(hole_node);
 260         u64 adj_start = hole_start;
 261         u64 adj_end = hole_end;
 262
 263         BUG_ON(!hole_node->hole_follows || node->allocated);
 264
 265         if (adj_start < start)
 266                 adj_start = start;
 267         if (adj_end > end)
 268                 adj_end = end;
 269
 270         if (mm->color_adjust)
 271                 mm->color_adjust(hole_node, color, &adj_start, &adj_end);
 272
 273         if (flags & DRM_MM_CREATE_TOP)
 274                 adj_start = adj_end - size;
 275
 276         if (alignment) {
 277                 u64 tmp = adj_start;
 278                 unsigned rem;
 279
 280                 rem = do_div(tmp, alignment);
 281                 if (rem) {
 282                         if (flags & DRM_MM_CREATE_TOP)
 283                                 adj_start -= rem;
 284                         else
 285                                 adj_start += alignment - rem;
 286                 }
 287         }
 288
 289         if (adj_start == hole_start) {
 290                 hole_node->hole_follows = 0;
 291                 list_del(&hole_node->hole_stack);
 292         }
 293
 294         node->start = adj_start;
 295         node->size = size;
 296         node->mm = mm;
 297         node->color = color;
 298         node->allocated = 1;
 299
 300         INIT_LIST_HEAD(&node->hole_stack);
 301         list_add(&node->node_list, &hole_node->node_list);
 302
 303         BUG_ON(node->start < start);
 304         BUG_ON(node->start < adj_start);
 305         BUG_ON(node->start + node->size > adj_end);
 306         BUG_ON(node->start + node->size > end);
 307
 308         node->hole_follows = 0;
 309         if (__drm_mm_hole_node_start(node) < hole_end) {
 310                 list_add(&node->hole_stack, &mm->hole_stack);
 311                 node->hole_follows = 1;
 312         }
 313 }
 314
 315 /**
 316  * drm_mm_insert_node_in_range_generic - ranged search for space and insert @node
 317  * @mm: drm_mm to allocate from
 318  * @node: preallocate node to insert
 319  * @size: size of the allocation
 320  * @alignment: alignment of the allocation
 321  * @color: opaque tag value to use for this node
 322  * @start: start of the allowed range for this node
 323  * @end: end of the allowed range for this node
 324  * @sflags: flags to fine-tune the allocation search
 325  * @aflags: flags to fine-tune the allocation behavior
 326  *
 327  * The preallocated node must be cleared to 0.
 328  *
 329  * Returns:
 330  * 0 on success, -ENOSPC if there's no suitable hole.
 331  */
 332 int drm_mm_insert_node_in_range_generic(struct drm_mm *mm, struct drm_mm_node *node,
 333                                         u64 size, unsigned alignment,
 334                                         unsigned long color,
 335                                         u64 start, u64 end,
 336                                         enum drm_mm_search_flags sflags,
 337                                         enum drm_mm_allocator_flags aflags)
 338 {
 339         struct drm_mm_node *hole_node;
 340
 341         hole_node = drm_mm_search_free_in_range_generic(mm,
 342                                                         size, alignment, color,
 343                                                         start, end, sflags);
 344         if (!hole_node)
 345                 return -ENOSPC;
 346
 347         drm_mm_insert_helper_range(hole_node, node,
 348                                    size, alignment, color,
 349                                    start, end, aflags);
 350         return 0;
 351 }
 352 EXPORT_SYMBOL(drm_mm_insert_node_in_range_generic);
 353
 354 /**
 355  * drm_mm_remove_node - Remove a memory node from the allocator.
 356  * @node: drm_mm_node to remove
 357  *
 358  * This just removes a node from its drm_mm allocator. The node does not need to
 359  * be cleared again before it can be re-inserted into this or any other drm_mm
 360  * allocator. It is a bug to call this function on a un-allocated node.
 361  */
 362 void drm_mm_remove_node(struct drm_mm_node *node)
 363 {
 364         struct drm_mm *mm = node->mm;
 365         struct drm_mm_node *prev_node;
 366
 367         if (WARN_ON(!node->allocated))
 368                 return;
 369
 370         BUG_ON(node->scanned_block || node->scanned_prev_free
 371                                    || node->scanned_next_free);
 372
 373         prev_node =
 374             list_entry(node->node_list.prev, struct drm_mm_node, node_list);
 375
 376         if (node->hole_follows) {
 377                 BUG_ON(__drm_mm_hole_node_start(node) ==
 378                        __drm_mm_hole_node_end(node));
 379                 list_del(&node->hole_stack);
 380         } else
 381                 BUG_ON(__drm_mm_hole_node_start(node) !=
 382                        __drm_mm_hole_node_end(node));
 383
 384
 385         if (!prev_node->hole_follows) {
 386                 prev_node->hole_follows = 1;
 387                 list_add(&prev_node->hole_stack, &mm->hole_stack);
 388         } else
 389                 list_move(&prev_node->hole_stack, &mm->hole_stack);
 390
 391         list_del(&node->node_list);
 392         node->allocated = 0;
 393 }
 394 EXPORT_SYMBOL(drm_mm_remove_node);
 395
 396 static int check_free_hole(u64 start, u64 end, u64 size, unsigned alignment)
 397 {
 398         if (end - start < size)
 399                 return 0;
 400
 401         if (alignment) {
 402                 u64 tmp = start;
 403                 unsigned rem;
 404
 405                 rem = do_div(tmp, alignment);
 406                 if (rem)
 407                         start += alignment - rem;
 408         }
 409
 410         return end >= start + size;
 411 }
 412
 413 static struct drm_mm_node *drm_mm_search_free_generic(const struct drm_mm *mm,
 414                                                       u64 size,
 415                                                       unsigned alignment,
 416                                                       unsigned long color,
 417                                                       enum drm_mm_search_flags flags)
 418 {
 419         struct drm_mm_node *entry;
 420         struct drm_mm_node *best;
 421         u64 adj_start;
 422         u64 adj_end;
 423         u64 best_size;
 424
 425         BUG_ON(mm->scanned_blocks);
 426
 427         best = NULL;
 428         best_size = ~0UL;
 429
 430         __drm_mm_for_each_hole(entry, mm, adj_start, adj_end,
 431                                flags & DRM_MM_SEARCH_BELOW) {
 432                 u64 hole_size = adj_end - adj_start;
 433
 434                 if (mm->color_adjust) {
 435                         mm->color_adjust(entry, color, &adj_start, &adj_end);
 436                         if (adj_end <= adj_start)
 437                                 continue;
 438                 }
 439
 440                 if (!check_free_hole(adj_start, adj_end, size, alignment))
 441                         continue;
 442
 443                 if (!(flags & DRM_MM_SEARCH_BEST))
 444                         return entry;
 445
 446                 if (hole_size < best_size) {
 447                         best = entry;
 448                         best_size = hole_size;
 449                 }
 450         }
 451
 452         return best;
 453 }
 454
 455 static struct drm_mm_node *drm_mm_search_free_in_range_generic(const struct drm_mm *mm,
 456                                                         u64 size,
 457                                                         unsigned alignment,
 458                                                         unsigned long color,
 459                                                         u64 start,
 460                                                         u64 end,
 461                                                         enum drm_mm_search_flags flags)
 462 {
 463         struct drm_mm_node *entry;
 464         struct drm_mm_node *best;
 465         u64 adj_start;
 466         u64 adj_end;
 467         u64 best_size;
 468
 469         BUG_ON(mm->scanned_blocks);
 470
 471         best = NULL;
 472         best_size = ~0UL;
 473
 474         __drm_mm_for_each_hole(entry, mm, adj_start, adj_end,
 475                                flags & DRM_MM_SEARCH_BELOW) {
 476                 u64 hole_size = adj_end - adj_start;
 477
 478                 if (adj_start < start)
 479                         adj_start = start;
 480                 if (adj_end > end)
 481                         adj_end = end;
 482
 483                 if (mm->color_adjust) {
 484                         mm->color_adjust(entry, color, &adj_start, &adj_end);
 485                         if (adj_end <= adj_start)
 486                                 continue;
 487                 }
 488
 489                 if (!check_free_hole(adj_start, adj_end, size, alignment))
 490                         continue;
 491
 492                 if (!(flags & DRM_MM_SEARCH_BEST))
 493                         return entry;
 494
 495                 if (hole_size < best_size) {
 496                         best = entry;
 497                         best_size = hole_size;
 498                 }
 499         }
 500
 501         return best;
 502 }
 503
 504 /**
 505  * drm_mm_replace_node - move an allocation from @old to @new
 506  * @old: drm_mm_node to remove from the allocator
 507  * @new: drm_mm_node which should inherit @old's allocation
 508  *
 509  * This is useful for when drivers embed the drm_mm_node structure and hence
 510  * can't move allocations by reassigning pointers. It's a combination of remove
 511  * and insert with the guarantee that the allocation start will match.
 512  */
 513 void drm_mm_replace_node(struct drm_mm_node *old, struct drm_mm_node *new)
 514 {
 515         list_replace(&old->node_list, &new->node_list);
 516         list_replace(&old->hole_stack, &new->hole_stack);
 517         new->hole_follows = old->hole_follows;
 518         new->mm = old->mm;
 519         new->start = old->start;
 520         new->size = old->size;
 521         new->color = old->color;
 522
 523         old->allocated = 0;
 524         new->allocated = 1;
 525 }
 526 EXPORT_SYMBOL(drm_mm_replace_node);
 527
 528 /**
 529  * DOC: lru scan roaster
 530  *
 531  * Very often GPUs need to have continuous allocations for a given object. When
 532  * evicting objects to make space for a new one it is therefore not most
 533  * efficient when we simply start to select all objects from the tail of an LRU
 534  * until there's a suitable hole: Especially for big objects or nodes that
 535  * otherwise have special allocation constraints there's a good chance we evict
 536  * lots of (smaller) objects unecessarily.
 537  *
 538  * The DRM range allocator supports this use-case through the scanning
 539  * interfaces. First a scan operation needs to be initialized with
 540  * drm_mm_init_scan() or drm_mm_init_scan_with_range(). The the driver adds
 541  * objects to the roaster (probably by walking an LRU list, but this can be
 542  * freely implemented) until a suitable hole is found or there's no further
 543  * evitable object.
 544  *
 545  * The the driver must walk through all objects again in exactly the reverse
 546  * order to restore the allocator state. Note that while the allocator is used
 547  * in the scan mode no other operation is allowed.
 548  *
 549  * Finally the driver evicts all objects selected in the scan. Adding and
 550  * removing an object is O(1), and since freeing a node is also O(1) the overall
 551  * complexity is O(scanned_objects). So like the free stack which needs to be
 552  * walked before a scan operation even begins this is linear in the number of
 553  * objects. It doesn't seem to hurt badly.
 554  */
 555
 556 /**
 557  * drm_mm_init_scan - initialize lru scanning
 558  * @mm: drm_mm to scan
 559  * @size: size of the allocation
 560  * @alignment: alignment of the allocation
 561  * @color: opaque tag value to use for the allocation
 562  *
 563  * This simply sets up the scanning routines with the parameters for the desired
 564  * hole. Note that there's no need to specify allocation flags, since they only
 565  * change the place a node is allocated from within a suitable hole.
 566  *
 567  * Warning:
 568  * As long as the scan list is non-empty, no other operations than
 569  * adding/removing nodes to/from the scan list are allowed.
 570  */
 571 void drm_mm_init_scan(struct drm_mm *mm,
 572                       u64 size,
 573                       unsigned alignment,
 574                       unsigned long color)
 575 {
 576         mm->scan_color = color;
 577         mm->scan_alignment = alignment;
 578         mm->scan_size = size;
 579         mm->scanned_blocks = 0;
 580         mm->scan_hit_start = 0;
 581         mm->scan_hit_end = 0;
 582         mm->scan_check_range = 0;
 583         mm->prev_scanned_node = NULL;
 584 }
 585 EXPORT_SYMBOL(drm_mm_init_scan);
 586
 587 /**
 588  * drm_mm_init_scan - initialize range-restricted lru scanning
 589  * @mm: drm_mm to scan
 590  * @size: size of the allocation
 591  * @alignment: alignment of the allocation
 592  * @color: opaque tag value to use for the allocation
 593  * @start: start of the allowed range for the allocation
 594  * @end: end of the allowed range for the allocation
 595  *
 596  * This simply sets up the scanning routines with the parameters for the desired
 597  * hole. Note that there's no need to specify allocation flags, since they only
 598  * change the place a node is allocated from within a suitable hole.
 599  *
 600  * Warning:
 601  * As long as the scan list is non-empty, no other operations than
 602  * adding/removing nodes to/from the scan list are allowed.
 603  */
 604 void drm_mm_init_scan_with_range(struct drm_mm *mm,
 605                                  u64 size,
 606                                  unsigned alignment,
 607                                  unsigned long color,
 608                                  u64 start,
 609                                  u64 end)
 610 {
 611         mm->scan_color = color;
 612         mm->scan_alignment = alignment;
 613         mm->scan_size = size;
 614         mm->scanned_blocks = 0;
 615         mm->scan_hit_start = 0;
 616         mm->scan_hit_end = 0;
 617         mm->scan_start = start;
 618         mm->scan_end = end;
 619         mm->scan_check_range = 1;
 620         mm->prev_scanned_node = NULL;
 621 }
 622 EXPORT_SYMBOL(drm_mm_init_scan_with_range);
 623
 624 /**
 625  * drm_mm_scan_add_block - add a node to the scan list
 626  * @node: drm_mm_node to add
 627  *
 628  * Add a node to the scan list that might be freed to make space for the desired
 629  * hole.
 630  *
 631  * Returns:
 632  * True if a hole has been found, false otherwise.
 633  */
 634 bool drm_mm_scan_add_block(struct drm_mm_node *node)
 635 {
 636         struct drm_mm *mm = node->mm;
 637         struct drm_mm_node *prev_node;
 638         u64 hole_start, hole_end;
 639         u64 adj_start, adj_end;
 640
 641         mm->scanned_blocks++;
 642
 643         BUG_ON(node->scanned_block);
 644         node->scanned_block = 1;
 645
 646         prev_node = list_entry(node->node_list.prev, struct drm_mm_node,
 647                                node_list);
 648
 649         node->scanned_preceeds_hole = prev_node->hole_follows;
 650         prev_node->hole_follows = 1;
 651         list_del(&node->node_list);
 652         node->node_list.prev = &prev_node->node_list;
 653         node->node_list.next = &mm->prev_scanned_node->node_list;
 654         mm->prev_scanned_node = node;
 655
 656         adj_start = hole_start = drm_mm_hole_node_start(prev_node);
 657         adj_end = hole_end = drm_mm_hole_node_end(prev_node);
 658
 659         if (mm->scan_check_range) {
 660                 if (adj_start < mm->scan_start)
 661                         adj_start = mm->scan_start;
 662                 if (adj_end > mm->scan_end)
 663                         adj_end = mm->scan_end;
 664         }
 665
 666         if (mm->color_adjust)
 667                 mm->color_adjust(prev_node, mm->scan_color,
 668                                  &adj_start, &adj_end);
 669
 670         if (check_free_hole(adj_start, adj_end,
 671                             mm->scan_size, mm->scan_alignment)) {
 672                 mm->scan_hit_start = hole_start;
 673                 mm->scan_hit_end = hole_end;
 674                 return true;
 675         }
 676
 677         return false;
 678 }
 679 EXPORT_SYMBOL(drm_mm_scan_add_block);
 680
 681 /**
 682  * drm_mm_scan_remove_block - remove a node from the scan list
 683  * @node: drm_mm_node to remove
 684  *
 685  * Nodes _must_ be removed in the exact same order from the scan list as they
 686  * have been added, otherwise the internal state of the memory manager will be
 687  * corrupted.
 688  *
 689  * When the scan list is empty, the selected memory nodes can be freed. An
 690  * immediately following drm_mm_search_free with !DRM_MM_SEARCH_BEST will then
 691  * return the just freed block (because its at the top of the free_stack list).
 692  *
 693  * Returns:
 694  * True if this block should be evicted, false otherwise. Will always
 695  * return false when no hole has been found.
 696  */
 697 bool drm_mm_scan_remove_block(struct drm_mm_node *node)
 698 {
 699         struct drm_mm *mm = node->mm;
 700         struct drm_mm_node *prev_node;
 701
 702         mm->scanned_blocks--;
 703
 704         BUG_ON(!node->scanned_block);
 705         node->scanned_block = 0;
 706
 707         prev_node = list_entry(node->node_list.prev, struct drm_mm_node,
 708                                node_list);
 709
 710         prev_node->hole_follows = node->scanned_preceeds_hole;
 711         list_add(&node->node_list, &prev_node->node_list);
 712
 713          return (drm_mm_hole_node_end(node) > mm->scan_hit_start &&
 714                  node->start < mm->scan_hit_end);
 715 }
 716 EXPORT_SYMBOL(drm_mm_scan_remove_block);
 717
 718 /**
 719  * drm_mm_clean - checks whether an allocator is clean
 720  * @mm: drm_mm allocator to check
 721  *
 722  * Returns:
 723  * True if the allocator is completely free, false if there's still a node
 724  * allocated in it.
 725  */
 726 bool drm_mm_clean(struct drm_mm * mm)
 727 {
 728         struct list_head *head = &mm->head_node.node_list;
 729
 730         return (head->next->next == head);
 731 }
 732 EXPORT_SYMBOL(drm_mm_clean);
 733
 734 /**
 735  * drm_mm_init - initialize a drm-mm allocator
 736  * @mm: the drm_mm structure to initialize
 737  * @start: start of the range managed by @mm
 738  * @size: end of the range managed by @mm
 739  *
 740  * Note that @mm must be cleared to 0 before calling this function.
 741  */
 742 void drm_mm_init(struct drm_mm * mm, u64 start, u64 size)
 743 {
 744         INIT_LIST_HEAD(&mm->hole_stack);
 745         mm->scanned_blocks = 0;
 746
 747         /* Clever trick to avoid a special case in the free hole tracking. */
 748         INIT_LIST_HEAD(&mm->head_node.node_list);
 749         INIT_LIST_HEAD(&mm->head_node.hole_stack);
 750         mm->head_node.hole_follows = 1;
 751         mm->head_node.scanned_block = 0;
 752         mm->head_node.scanned_prev_free = 0;
 753         mm->head_node.scanned_next_free = 0;
 754         mm->head_node.mm = mm;
 755         mm->head_node.start = start + size;
 756         mm->head_node.size = start - mm->head_node.start;
 757         list_add_tail(&mm->head_node.hole_stack, &mm->hole_stack);
 758
 759         mm->color_adjust = NULL;
 760 }
 761 EXPORT_SYMBOL(drm_mm_init);
 762
 763 /**
 764  * drm_mm_takedown - clean up a drm_mm allocator
 765  * @mm: drm_mm allocator to clean up
 766  *
 767  * Note that it is a bug to call this function on an allocator which is not
 768  * clean.
 769  */
 770 void drm_mm_takedown(struct drm_mm * mm)
 771 {
 772         WARN(!list_empty(&mm->head_node.node_list),
 773              "Memory manager not clean during takedown.\n");
 774 }
 775 EXPORT_SYMBOL(drm_mm_takedown);
 776
 777 static u64 drm_mm_debug_hole(struct drm_mm_node *entry,
 778                                      const char *prefix)
 779 {
 780         u64 hole_start, hole_end, hole_size;
 781
 782         if (entry->hole_follows) {
 783                 hole_start = drm_mm_hole_node_start(entry);
 784                 hole_end = drm_mm_hole_node_end(entry);
 785                 hole_size = hole_end - hole_start;
 786                 pr_debug("%s %#llx-%#llx: %llu: free\n", prefix, hole_start,
 787                          hole_end, hole_size);
 788                 return hole_size;
 789         }
 790
 791         return 0;
 792 }
 793
 794 /**
 795  * drm_mm_debug_table - dump allocator state to dmesg
 796  * @mm: drm_mm allocator to dump
 797  * @prefix: prefix to use for dumping to dmesg
 798  */
 799 void drm_mm_debug_table(struct drm_mm *mm, const char *prefix)
 800 {
 801         struct drm_mm_node *entry;
 802         u64 total_used = 0, total_free = 0, total = 0;
 803
 804         total_free += drm_mm_debug_hole(&mm->head_node, prefix);
 805
 806         drm_mm_for_each_node(entry, mm) {
 807                 pr_debug("%s %#llx-%#llx: %llu: used\n", prefix, entry->start,
 808                          entry->start + entry->size, entry->size);
 809                 total_used += entry->size;
 810                 total_free += drm_mm_debug_hole(entry, prefix);
 811         }
 812         total = total_free + total_used;
 813
 814         pr_debug("%s total: %llu, used %llu free %llu\n", prefix, total,
 815                  total_used, total_free);
 816 }
 817 EXPORT_SYMBOL(drm_mm_debug_table);
 818
 819 #if defined(CONFIG_DEBUG_FS)
 820 static u64 drm_mm_dump_hole(struct seq_file *m, struct drm_mm_node *entry)
 821 {
 822         u64 hole_start, hole_end, hole_size;
 823
 824         if (entry->hole_follows) {
 825                 hole_start = drm_mm_hole_node_start(entry);
 826                 hole_end = drm_mm_hole_node_end(entry);
 827                 hole_size = hole_end - hole_start;
 828                 seq_printf(m, "%#018llx-%#018llx: %llu: free\n", hole_start,
 829                            hole_end, hole_size);
 830                 return hole_size;
 831         }
 832
 833         return 0;
 834 }
 835
 836 /**
 837  * drm_mm_dump_table - dump allocator state to a seq_file
 838  * @m: seq_file to dump to
 839  * @mm: drm_mm allocator to dump
 840  */
 841 int drm_mm_dump_table(struct seq_file *m, struct drm_mm *mm)
 842 {
 843         struct drm_mm_node *entry;
 844         u64 total_used = 0, total_free = 0, total = 0;
 845
 846         total_free += drm_mm_dump_hole(m, &mm->head_node);
 847
 848         drm_mm_for_each_node(entry, mm) {
 849                 seq_printf(m, "%#018llx-%#018llx: %llu: used\n", entry->start,
 850                            entry->start + entry->size, entry->size);
 851                 total_used += entry->size;
 852                 total_free += drm_mm_dump_hole(m, entry);
 853         }
 854         total = total_free + total_used;
 855
 856         seq_printf(m, "total: %llu, used %llu free %llu\n", total,
 857                    total_used, total_free);
 858         return 0;
 859 }
 860 EXPORT_SYMBOL(drm_mm_dump_table);
 861 #endif