1 /* Free a block of memory allocated by `mmalloc'. */
3 /* Copyright (c) 2010-2017. 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)
27 // fprintf(stderr,"free(%p)\n",ptr);
32 size_t block = BLOCK(ptr);
34 if ((char *) ptr < (char *) mdp->heapbase || block > mdp->heapsize) {
35 fprintf(stderr,"Ouch, this pointer is not mine, I refuse to free it. Give me valid pointers, or give me death!!\n");
39 int type = mdp->heapinfo[block].type;
42 case MMALLOC_TYPE_HEAPINFO:
44 THROWF(system_error, 0, "Asked to free a fragment in a heapinfo block. I'm confused.\n");
47 case MMALLOC_TYPE_FREE: /* Already free */
49 THROWF(system_error, 0, "Asked to free a fragment in a block that is already free. I'm puzzled.\n");
52 case MMALLOC_TYPE_UNFRAGMENTED:
53 /* Get as many statistics as early as we can. */
54 mdp -> heapstats.chunks_used--;
55 mdp -> heapstats.bytes_used -=
56 mdp -> heapinfo[block].busy_block.size * BLOCKSIZE;
57 mdp -> heapstats.bytes_free +=
58 mdp -> heapinfo[block].busy_block.size * BLOCKSIZE;
60 if (MC_is_active() && mdp->heapinfo[block].busy_block.ignore > 0)
61 MC_unignore_heap(ptr, mdp->heapinfo[block].busy_block.busy_size);
63 /* Find the free cluster previous to this one in the free list.
64 Start searching at the last block referenced; this may benefit
65 programs with locality of allocation. */
69 i = mdp->heapinfo[i].free_block.prev;
73 i = mdp->heapinfo[i].free_block.next;
75 while ((i != 0) && (i < block));
76 i = mdp->heapinfo[i].free_block.prev;
79 /* Determine how to link this block into the free list. */
80 if (block == i + mdp->heapinfo[i].free_block.size) {
82 /* Coalesce this block with its predecessor. */
83 mdp->heapinfo[i].free_block.size += mdp->heapinfo[block].busy_block.size;
84 /* Mark all my ex-blocks as free */
85 for (it=0; it<mdp->heapinfo[block].busy_block.size; it++) {
86 if (mdp->heapinfo[block+it].type < 0) {
87 fprintf(stderr,"Internal Error: Asked to free a block already marked as free (block=%lu it=%d type=%lu). Please report this bug.\n",
88 (unsigned long)block,it,(unsigned long)mdp->heapinfo[block].type);
91 mdp->heapinfo[block+it].type = MMALLOC_TYPE_FREE;
96 //fprintf(stderr,"Free block %d to %d (as a new chunck)\n",block,block+mdp->heapinfo[block].busy_block.size);
97 /* Really link this block back into the free list. */
98 mdp->heapinfo[block].free_block.size = mdp->heapinfo[block].busy_block.size;
99 mdp->heapinfo[block].free_block.next = mdp->heapinfo[i].free_block.next;
100 mdp->heapinfo[block].free_block.prev = i;
101 mdp->heapinfo[i].free_block.next = block;
102 mdp->heapinfo[mdp->heapinfo[block].free_block.next].free_block.prev = block;
103 mdp -> heapstats.chunks_free++;
104 /* Mark all my ex-blocks as free */
105 for (it=0; it<mdp->heapinfo[block].free_block.size; it++) {
106 if (mdp->heapinfo[block+it].type <0) {
107 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",
108 (unsigned long)block,it,(unsigned long)mdp->heapinfo[block].free_block.size,(unsigned long)mdp->heapinfo[block].type);
111 mdp->heapinfo[block+it].type = MMALLOC_TYPE_FREE;
115 /* Now that the block is linked in, see if we can coalesce it
116 with its successor (by deleting its successor from the list
117 and adding in its size). */
118 if (block + mdp->heapinfo[block].free_block.size ==
119 mdp->heapinfo[block].free_block.next) {
120 mdp->heapinfo[block].free_block.size
121 += mdp->heapinfo[mdp->heapinfo[block].free_block.next].free_block.size;
122 mdp->heapinfo[block].free_block.next
123 = mdp->heapinfo[mdp->heapinfo[block].free_block.next].free_block.next;
124 mdp->heapinfo[mdp->heapinfo[block].free_block.next].free_block.prev = block;
125 mdp -> heapstats.chunks_free--;
128 /* Now see if we can return stuff to the system. */
129 /* blocks = mdp -> heapinfo[block].free.size;
130 if (blocks >= FINAL_FREE_BLOCKS && block + blocks == mdp -> heaplimit
131 && mdp -> morecore (mdp, 0) == ADDRESS (block + blocks))
133 register size_t bytes = blocks * BLOCKSIZE;
134 mdp -> heaplimit -= blocks;
135 mdp -> morecore (mdp, -bytes);
136 mdp -> heapinfo[mdp -> heapinfo[block].free.prev].free.next
137 = mdp -> heapinfo[block].free.next;
138 mdp -> heapinfo[mdp -> heapinfo[block].free.next].free.prev
139 = mdp -> heapinfo[block].free.prev;
140 block = mdp -> heapinfo[block].free.prev;
141 mdp -> heapstats.chunks_free--;
142 mdp -> heapstats.bytes_free -= bytes;
145 /* Set the next search to begin at this block.
146 This is probably important to the trick where realloc returns the block to
147 the system before reasking for the same block with a bigger size. */
148 mdp->heapindex = block;
153 fprintf(stderr, "Unkown mmalloc block type.\n");
157 /* Do some of the statistics. */
158 mdp -> heapstats.chunks_used--;
159 mdp -> heapstats.bytes_used -= 1 << type;
160 mdp -> heapstats.chunks_free++;
161 mdp -> heapstats.bytes_free += 1 << type;
163 frag_nb = RESIDUAL(ptr, BLOCKSIZE) >> type;
165 if( mdp->heapinfo[block].busy_frag.frag_size[frag_nb] == -1){
167 THROWF(system_error, 0, "Asked to free a fragment that is already free. I'm puzzled\n");
170 if (MC_is_active() && mdp->heapinfo[block].busy_frag.ignore[frag_nb] > 0)
171 MC_unignore_heap(ptr, mdp->heapinfo[block].busy_frag.frag_size[frag_nb]);
173 /* Set size used in the fragment to -1 */
174 mdp->heapinfo[block].busy_frag.frag_size[frag_nb] = -1;
175 mdp->heapinfo[block].busy_frag.ignore[frag_nb] = 0;
177 // fprintf(stderr,"nfree:%zu capa:%d\n", mdp->heapinfo[block].busy_frag.nfree,(BLOCKSIZE >> type));
178 if (mdp->heapinfo[block].busy_frag.nfree ==
179 (BLOCKSIZE >> type) - 1) {
180 /* If all fragments of this block are free, remove this block from its swag and free the whole block. */
181 xbt_swag_remove(&mdp->heapinfo[block],&mdp->fraghead[type]);
183 /* pretend that this block is used and free it so that it gets properly coalesced with adjacent free blocks */
184 mdp->heapinfo[block].type = MMALLOC_TYPE_UNFRAGMENTED;
185 mdp->heapinfo[block].busy_block.size = 1;
186 mdp->heapinfo[block].busy_block.busy_size = 0;
188 /* Keep the statistics accurate. */
189 mdp -> heapstats.chunks_used++;
190 mdp -> heapstats.bytes_used += BLOCKSIZE;
191 mdp -> heapstats.chunks_free -= BLOCKSIZE >> type;
192 mdp -> heapstats.bytes_free -= BLOCKSIZE;
194 mfree((void *) mdp, (void *) ADDRESS(block));
195 } else if (mdp->heapinfo[block].busy_frag.nfree != 0) {
196 /* If some fragments of this block are free, you know what? I'm already happy. */
197 ++mdp->heapinfo[block].busy_frag.nfree;
199 /* No fragments of this block were free before the one we just released,
200 * so add this block to the swag and announce that
201 it is the first free fragment of this block. */
202 mdp->heapinfo[block].busy_frag.nfree = 1;
203 mdp->heapinfo[block].freehook.prev = NULL;
204 mdp->heapinfo[block].freehook.next = NULL;
206 xbt_swag_insert(&mdp->heapinfo[block],&mdp->fraghead[type]);