drm_mm.c

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    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 #include <sys/cdefs.h>
   30 __FBSDID("$FreeBSD$");
   31 
   32 /*
   33  * Generic simple memory manager implementation. Intended to be used as a base
   34  * class implementation for more advanced memory managers.
   35  *
   36  * Note that the algorithm used is quite simple and there might be substantial
   37  * performance gains if a smarter free list is implemented. Currently it is just an
   38  * unordered stack of free regions. This could easily be improved if an RB-tree
   39  * is used instead. At least if we expect heavy fragmentation.
   40  *
   41  * Aligned allocations can also see improvement.
   42  *
   43  * Authors:
   44  * Thomas Hellström <thomas-at-tungstengraphics-dot-com>
   45  */
   46 
   47 #include "dev/drm/drmP.h"
   48 #include "dev/drm/drm_mm.h"
   49 
   50 #define MM_UNUSED_TARGET 4
   51 
   52 unsigned long drm_mm_tail_space(struct drm_mm *mm)
   53 {
   54         struct list_head *tail_node;
   55         struct drm_mm_node *entry;
   56 
   57         tail_node = mm->ml_entry.prev;
   58         entry = list_entry(tail_node, struct drm_mm_node, ml_entry);
   59         if (!entry->free)
   60                 return 0;
   61 
   62         return entry->size;
   63 }
   64 
   65 int drm_mm_remove_space_from_tail(struct drm_mm *mm, unsigned long size)
   66 {
   67         struct list_head *tail_node;
   68         struct drm_mm_node *entry;
   69 
   70         tail_node = mm->ml_entry.prev;
   71         entry = list_entry(tail_node, struct drm_mm_node, ml_entry);
   72         if (!entry->free)
   73                 return -ENOMEM;
   74 
   75         if (entry->size <= size)
   76                 return -ENOMEM;
   77 
   78         entry->size -= size;
   79         return 0;
   80 }
   81 
   82 static struct drm_mm_node *drm_mm_kmalloc(struct drm_mm *mm, int atomic)
   83 {
   84         struct drm_mm_node *child;
   85 
   86         if (atomic)
   87                 child = malloc(sizeof(*child), DRM_MEM_MM, M_NOWAIT);
   88         else
   89                 child = malloc(sizeof(*child), DRM_MEM_MM, M_WAITOK);
   90 
   91         if (unlikely(child == NULL)) {
   92                 mtx_lock(&mm->unused_lock);
   93                 if (list_empty(&mm->unused_nodes))
   94                         child = NULL;
   95                 else {
   96                         child =
   97                             list_entry(mm->unused_nodes.next,
   98                                        struct drm_mm_node, fl_entry);
   99                         list_del(&child->fl_entry);
  100                         --mm->num_unused;
  101                 }
  102                 mtx_unlock(&mm->unused_lock);
  103         }
  104         return child;
  105 }
  106 
  107 int drm_mm_pre_get(struct drm_mm *mm)
  108 {
  109         struct drm_mm_node *node;
  110 
  111         mtx_lock(&mm->unused_lock);
  112         while (mm->num_unused < MM_UNUSED_TARGET) {
  113                 mtx_unlock(&mm->unused_lock);
  114                 node = malloc(sizeof(*node), DRM_MEM_MM, M_WAITOK);
  115                 mtx_lock(&mm->unused_lock);
  116 
  117                 if (unlikely(node == NULL)) {
  118                         int ret = (mm->num_unused < 2) ? -ENOMEM : 0;
  119                         mtx_unlock(&mm->unused_lock);
  120                         return ret;
  121                 }
  122                 ++mm->num_unused;
  123                 list_add_tail(&node->fl_entry, &mm->unused_nodes);
  124         }
  125         mtx_unlock(&mm->unused_lock);
  126         return 0;
  127 }
  128 
  129 static int drm_mm_create_tail_node(struct drm_mm *mm,
  130                                    unsigned long start,
  131                                    unsigned long size, int atomic)
  132 {
  133         struct drm_mm_node *child;
  134 
  135         child = drm_mm_kmalloc(mm, atomic);
  136         if (unlikely(child == NULL))
  137                 return -ENOMEM;
  138 
  139         child->free = 1;
  140         child->size = size;
  141         child->start = start;
  142         child->mm = mm;
  143 
  144         list_add_tail(&child->ml_entry, &mm->ml_entry);
  145         list_add_tail(&child->fl_entry, &mm->fl_entry);
  146 
  147         return 0;
  148 }
  149 
  150 int drm_mm_add_space_to_tail(struct drm_mm *mm, unsigned long size, int atomic)
  151 {
  152         struct list_head *tail_node;
  153         struct drm_mm_node *entry;
  154 
  155         tail_node = mm->ml_entry.prev;
  156         entry = list_entry(tail_node, struct drm_mm_node, ml_entry);
  157         if (!entry->free) {
  158                 return drm_mm_create_tail_node(mm, entry->start + entry->size,
  159                                                size, atomic);
  160         }
  161         entry->size += size;
  162         return 0;
  163 }
  164 
  165 static struct drm_mm_node *drm_mm_split_at_start(struct drm_mm_node *parent,
  166                                                  unsigned long size,
  167                                                  int atomic)
  168 {
  169         struct drm_mm_node *child;
  170 
  171         child = drm_mm_kmalloc(parent->mm, atomic);
  172         if (unlikely(child == NULL))
  173                 return NULL;
  174 
  175         INIT_LIST_HEAD(&child->fl_entry);
  176 
  177         child->free = 0;
  178         child->size = size;
  179         child->start = parent->start;
  180         child->mm = parent->mm;
  181 
  182         list_add_tail(&child->ml_entry, &parent->ml_entry);
  183         INIT_LIST_HEAD(&child->fl_entry);
  184 
  185         parent->size -= size;
  186         parent->start += size;
  187         return child;
  188 }
  189 
  190 
  191 struct drm_mm_node *drm_mm_get_block_generic(struct drm_mm_node *node,
  192                                              unsigned long size,
  193                                              unsigned alignment,
  194                                              int atomic)
  195 {
  196 
  197         struct drm_mm_node *align_splitoff = NULL;
  198         unsigned tmp = 0;
  199 
  200         if (alignment)
  201                 tmp = node->start % alignment;
  202 
  203         if (tmp) {
  204                 align_splitoff =
  205                     drm_mm_split_at_start(node, alignment - tmp, atomic);
  206                 if (unlikely(align_splitoff == NULL))
  207                         return NULL;
  208         }
  209 
  210         if (node->size == size) {
  211                 list_del_init(&node->fl_entry);
  212                 node->free = 0;
  213         } else {
  214                 node = drm_mm_split_at_start(node, size, atomic);
  215         }
  216 
  217         if (align_splitoff)
  218                 drm_mm_put_block(align_splitoff);
  219 
  220         return node;
  221 }
  222 
  223 /*
  224  * Put a block. Merge with the previous and / or next block if they are free.
  225  * Otherwise add to the free stack.
  226  */
  227 
  228 void drm_mm_put_block(struct drm_mm_node *cur)
  229 {
  230 
  231         struct drm_mm *mm = cur->mm;
  232         struct list_head *cur_head = &cur->ml_entry;
  233         struct list_head *root_head = &mm->ml_entry;
  234         struct drm_mm_node *prev_node = NULL;
  235         struct drm_mm_node *next_node;
  236 
  237         int merged = 0;
  238 
  239         if (cur_head->prev != root_head) {
  240                 prev_node =
  241                     list_entry(cur_head->prev, struct drm_mm_node, ml_entry);
  242                 if (prev_node->free) {
  243                         prev_node->size += cur->size;
  244                         merged = 1;
  245                 }
  246         }
  247         if (cur_head->next != root_head) {
  248                 next_node =
  249                     list_entry(cur_head->next, struct drm_mm_node, ml_entry);
  250                 if (next_node->free) {
  251                         if (merged) {
  252                                 prev_node->size += next_node->size;
  253                                 list_del(&next_node->ml_entry);
  254                                 list_del(&next_node->fl_entry);
  255                                 if (mm->num_unused < MM_UNUSED_TARGET) {
  256                                         list_add(&next_node->fl_entry,
  257                                                  &mm->unused_nodes);
  258                                         ++mm->num_unused;
  259                                 } else
  260                                         free(next_node, DRM_MEM_MM);
  261                         } else {
  262                                 next_node->size += cur->size;
  263                                 next_node->start = cur->start;
  264                                 merged = 1;
  265                         }
  266                 }
  267         }
  268         if (!merged) {
  269                 cur->free = 1;
  270                 list_add(&cur->fl_entry, &mm->fl_entry);
  271         } else {
  272                 list_del(&cur->ml_entry);
  273                 if (mm->num_unused < MM_UNUSED_TARGET) {
  274                         list_add(&cur->fl_entry, &mm->unused_nodes);
  275                         ++mm->num_unused;
  276                 } else
  277                         free(cur, DRM_MEM_MM);
  278         }
  279 }
  280 
  281 struct drm_mm_node *drm_mm_search_free(const struct drm_mm *mm,
  282                                        unsigned long size,
  283                                        unsigned alignment, int best_match)
  284 {
  285         struct list_head *list;
  286         const struct list_head *free_stack = &mm->fl_entry;
  287         struct drm_mm_node *entry;
  288         struct drm_mm_node *best;
  289         unsigned long best_size;
  290         unsigned wasted;
  291 
  292         best = NULL;
  293         best_size = ~0UL;
  294 
  295         list_for_each(list, free_stack) {
  296                 entry = list_entry(list, struct drm_mm_node, fl_entry);
  297                 wasted = 0;
  298 
  299                 if (entry->size < size)
  300                         continue;
  301 
  302                 if (alignment) {
  303                         register unsigned tmp = entry->start % alignment;
  304                         if (tmp)
  305                                 wasted += alignment - tmp;
  306                 }
  307 
  308                 if (entry->size >= size + wasted) {
  309                         if (!best_match)
  310                                 return entry;
  311                         if (size < best_size) {
  312                                 best = entry;
  313                                 best_size = entry->size;
  314                         }
  315                 }
  316         }
  317 
  318         return best;
  319 }
  320 
  321 int drm_mm_clean(struct drm_mm * mm)
  322 {
  323         struct list_head *head = &mm->ml_entry;
  324 
  325         return (head->next->next == head);
  326 }
  327 
  328 int drm_mm_init(struct drm_mm * mm, unsigned long start, unsigned long size)
  329 {
  330         INIT_LIST_HEAD(&mm->ml_entry);
  331         INIT_LIST_HEAD(&mm->fl_entry);
  332         INIT_LIST_HEAD(&mm->unused_nodes);
  333         mm->num_unused = 0;
  334         mtx_init(&mm->unused_lock, "drm_unused", NULL, MTX_DEF);
  335 
  336         /* XXX This could be non-atomic but gets called from a locked path */
  337         return drm_mm_create_tail_node(mm, start, size, 1);
  338 }
  339 
  340 void drm_mm_takedown(struct drm_mm * mm)
  341 {
  342         struct list_head *bnode = mm->fl_entry.next;
  343         struct drm_mm_node *entry;
  344         struct drm_mm_node *next;
  345 
  346         entry = list_entry(bnode, struct drm_mm_node, fl_entry);
  347 
  348         if (entry->ml_entry.next != &mm->ml_entry ||
  349             entry->fl_entry.next != &mm->fl_entry) {
  350                 DRM_ERROR("Memory manager not clean. Delaying takedown\n");
  351                 return;
  352         }
  353 
  354         list_del(&entry->fl_entry);
  355         list_del(&entry->ml_entry);
  356         free(entry, DRM_MEM_MM);
  357 
  358         mtx_lock(&mm->unused_lock);
  359         list_for_each_entry_safe(entry, next, &mm->unused_nodes, fl_entry) {
  360                 list_del(&entry->fl_entry);
  361                 free(entry, DRM_MEM_MM);
  362                 --mm->num_unused;
  363         }
  364         mtx_unlock(&mm->unused_lock);
  365 
  366         mtx_destroy(&mm->unused_lock);
  367 
  368         KASSERT(mm->num_unused == 0, ("num_unused != 0"));
  369 }
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FreeBSD/Linux Kernel Cross Reference sys/dev/drm/drm_mm.c

FreeBSD/Linux Kernel Cross Reference
sys/dev/drm/drm_mm.c
