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