1 /* Free a block of memory allocated by `mmalloc'. */
3 /* Copyright (c) 2010-2019. The SimGrid Team. All rights reserved. */
5 /* This program is free software; you can redistribute it and/or modify it
6 * under the terms of the license (GNU LGPL) which comes with this package. */
8 /* Copyright 1990, 1991, 1992 Free Software Foundation
10 Written May 1989 by Mike Haertel.
11 Heavily modified Mar 1992 by Fred Fish. (fnf@cygnus.com) */
13 #include "mmprivate.h"
17 /* Return memory to the heap.
18 Like `mfree' but don't call a mfree_hook if there is one. */
20 /* Return memory to the heap. */
21 void mfree(struct mdesc *mdp, void *ptr)
30 size_t block = BLOCK(ptr);
32 if ((char *) ptr < (char *) mdp->heapbase || block > mdp->heapsize) {
33 fprintf(stderr,"Ouch, this pointer is not mine, I refuse to free it. Give me valid pointers, or give me death!!\n");
37 int type = mdp->heapinfo[block].type;
40 case MMALLOC_TYPE_HEAPINFO:
42 THROWF(0, "Asked to free a fragment in a heapinfo block. I'm confused.\n");
45 case MMALLOC_TYPE_FREE: /* Already free */
47 THROWF(0, "Asked to free a fragment in a block that is already free. I'm puzzled.\n");
50 case MMALLOC_TYPE_UNFRAGMENTED:
51 /* Get as many statistics as early as we can. */
52 mdp -> heapstats.chunks_used--;
53 mdp -> heapstats.bytes_used -=
54 mdp -> heapinfo[block].busy_block.size * BLOCKSIZE;
55 mdp -> heapstats.bytes_free +=
56 mdp -> heapinfo[block].busy_block.size * BLOCKSIZE;
58 if (MC_is_active() && mdp->heapinfo[block].busy_block.ignore > 0)
59 MC_unignore_heap(ptr, mdp->heapinfo[block].busy_block.busy_size);
61 /* Find the free cluster previous to this one in the free list.
62 Start searching at the last block referenced; this may benefit
63 programs with locality of allocation. */
67 i = mdp->heapinfo[i].free_block.prev;
71 i = mdp->heapinfo[i].free_block.next;
73 while ((i != 0) && (i < block));
74 i = mdp->heapinfo[i].free_block.prev;
77 /* Determine how to link this block into the free list. */
78 if (block == i + mdp->heapinfo[i].free_block.size) {
80 /* Coalesce this block with its predecessor. */
81 mdp->heapinfo[i].free_block.size += mdp->heapinfo[block].busy_block.size;
82 /* Mark all my ex-blocks as free */
83 for (it=0; it<mdp->heapinfo[block].busy_block.size; it++) {
84 if (mdp->heapinfo[block+it].type < 0) {
85 fprintf(stderr,"Internal Error: Asked to free a block already marked as free (block=%lu it=%d type=%lu). Please report this bug.\n",
86 (unsigned long)block,it,(unsigned long)mdp->heapinfo[block].type);
89 mdp->heapinfo[block+it].type = MMALLOC_TYPE_FREE;
94 /* Really link this block back into the free list. */
95 mdp->heapinfo[block].free_block.size = mdp->heapinfo[block].busy_block.size;
96 mdp->heapinfo[block].free_block.next = mdp->heapinfo[i].free_block.next;
97 mdp->heapinfo[block].free_block.prev = i;
98 mdp->heapinfo[i].free_block.next = block;
99 mdp->heapinfo[mdp->heapinfo[block].free_block.next].free_block.prev = block;
100 mdp -> heapstats.chunks_free++;
101 /* Mark all my ex-blocks as free */
102 for (it=0; it<mdp->heapinfo[block].free_block.size; it++) {
103 if (mdp->heapinfo[block+it].type <0) {
104 fprintf(stderr,"Internal error: Asked to free a block already marked as free (block=%lu it=%d/%lu type=%lu). Please report this bug.\n",
105 (unsigned long)block,it,(unsigned long)mdp->heapinfo[block].free_block.size,(unsigned long)mdp->heapinfo[block].type);
108 mdp->heapinfo[block+it].type = MMALLOC_TYPE_FREE;
112 /* Now that the block is linked in, see if we can coalesce it
113 with its successor (by deleting its successor from the list
114 and adding in its size). */
115 if (block + mdp->heapinfo[block].free_block.size ==
116 mdp->heapinfo[block].free_block.next) {
117 mdp->heapinfo[block].free_block.size
118 += mdp->heapinfo[mdp->heapinfo[block].free_block.next].free_block.size;
119 mdp->heapinfo[block].free_block.next
120 = mdp->heapinfo[mdp->heapinfo[block].free_block.next].free_block.next;
121 mdp->heapinfo[mdp->heapinfo[block].free_block.next].free_block.prev = block;
122 mdp -> heapstats.chunks_free--;
125 /* Now see if we can return stuff to the system. */
127 blocks = mdp -> heapinfo[block].free.size;
128 if (blocks >= FINAL_FREE_BLOCKS && block + blocks == mdp -> heaplimit
129 && mdp -> morecore (mdp, 0) == ADDRESS (block + blocks))
131 register size_t bytes = blocks * BLOCKSIZE;
132 mdp -> heaplimit -= blocks;
133 mdp -> morecore (mdp, -bytes);
134 mdp -> heapinfo[mdp -> heapinfo[block].free.prev].free.next
135 = mdp -> heapinfo[block].free.next;
136 mdp -> heapinfo[mdp -> heapinfo[block].free.next].free.prev
137 = mdp -> heapinfo[block].free.prev;
138 block = mdp -> heapinfo[block].free.prev;
139 mdp -> heapstats.chunks_free--;
140 mdp -> heapstats.bytes_free -= bytes;
144 /* Set the next search to begin at this block.
145 This is probably important to the trick where realloc returns the block to
146 the system before reasking for the same block with a bigger size. */
147 mdp->heapindex = block;
152 fprintf(stderr, "Unkown mmalloc block type.\n");
156 /* Do some of the statistics. */
157 mdp -> heapstats.chunks_used--;
158 mdp -> heapstats.bytes_used -= 1 << type;
159 mdp -> heapstats.chunks_free++;
160 mdp -> heapstats.bytes_free += 1 << type;
162 frag_nb = RESIDUAL(ptr, BLOCKSIZE) >> type;
164 if( mdp->heapinfo[block].busy_frag.frag_size[frag_nb] == -1){
166 THROWF(0, "Asked to free a fragment that is already free. I'm puzzled\n");
169 if (MC_is_active() && mdp->heapinfo[block].busy_frag.ignore[frag_nb] > 0)
170 MC_unignore_heap(ptr, mdp->heapinfo[block].busy_frag.frag_size[frag_nb]);
172 /* Set size used in the fragment to -1 */
173 mdp->heapinfo[block].busy_frag.frag_size[frag_nb] = -1;
174 mdp->heapinfo[block].busy_frag.ignore[frag_nb] = 0;
176 if (mdp->heapinfo[block].busy_frag.nfree ==
177 (BLOCKSIZE >> type) - 1) {
178 /* If all fragments of this block are free, remove this block from its swag and free the whole block. */
179 xbt_swag_remove(&mdp->heapinfo[block],&mdp->fraghead[type]);
181 /* pretend that this block is used and free it so that it gets properly coalesced with adjacent free blocks */
182 mdp->heapinfo[block].type = MMALLOC_TYPE_UNFRAGMENTED;
183 mdp->heapinfo[block].busy_block.size = 1;
184 mdp->heapinfo[block].busy_block.busy_size = 0;
186 /* Keep the statistics accurate. */
187 mdp -> heapstats.chunks_used++;
188 mdp -> heapstats.bytes_used += BLOCKSIZE;
189 mdp -> heapstats.chunks_free -= BLOCKSIZE >> type;
190 mdp -> heapstats.bytes_free -= BLOCKSIZE;
192 mfree((void *) mdp, (void *) ADDRESS(block));
193 } else if (mdp->heapinfo[block].busy_frag.nfree != 0) {
194 /* If some fragments of this block are free, you know what? I'm already happy. */
195 ++mdp->heapinfo[block].busy_frag.nfree;
197 /* No fragments of this block were free before the one we just released,
198 * so add this block to the swag and announce that
199 it is the first free fragment of this block. */
200 mdp->heapinfo[block].busy_frag.nfree = 1;
201 mdp->heapinfo[block].freehook.prev = NULL;
202 mdp->heapinfo[block].freehook.next = NULL;
204 xbt_swag_insert(&mdp->heapinfo[block],&mdp->fraghead[type]);