265 lines
7.6 KiB
C
265 lines
7.6 KiB
C
/****************************************************************************
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* mm/mm_heap/mm_malloc.c
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*
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* Copyright (C) 2007, 2009, 2013-2014, 2017 Gregory Nutt. All rights
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* reserved.
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* Author: Gregory Nutt <gnutt@nuttx.org>
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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* 3. Neither the name NuttX nor the names of its contributors may be
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* used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
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* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
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* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
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* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*
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****************************************************************************/
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/****************************************************************************
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* Included Files
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****************************************************************************/
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#include <nuttx/config.h>
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#include <assert.h>
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#include <debug.h>
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#include <string.h>
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#include <nuttx/arch.h>
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#include <nuttx/mm/mm.h>
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/****************************************************************************
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* Pre-processor Definitions
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****************************************************************************/
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#ifndef NULL
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# define NULL ((void *)0)
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#endif
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/****************************************************************************
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* Private Functions
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****************************************************************************/
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#if defined(CONFIG_BUILD_FLAT) || defined(__KERNEL__)
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static void mm_free_delaylist(FAR struct mm_heap_s *heap)
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{
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FAR struct mm_delaynode_s *tmp;
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irqstate_t flags;
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/* Move the delay list to local */
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flags = enter_critical_section();
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tmp = heap->mm_delaylist;
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heap->mm_delaylist = NULL;
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leave_critical_section(flags);
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/* Test if the delayed is empty */
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while (tmp)
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{
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FAR void *address;
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/* Get the first delayed deallocation */
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address = tmp;
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tmp = tmp->flink;
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/* The address should always be non-NULL since that was checked in the
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* 'while' condition above.
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*/
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mm_free(heap, address);
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}
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}
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#endif
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: mm_malloc
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*
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* Description:
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* Find the smallest chunk that satisfies the request. Take the memory from
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* that chunk, save the remaining, smaller chunk (if any).
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*
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* 8-byte alignment of the allocated data is assured.
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*
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****************************************************************************/
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FAR void *mm_malloc(FAR struct mm_heap_s *heap, size_t size)
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{
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FAR struct mm_freenode_s *node;
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size_t alignsize;
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void *ret = NULL;
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int ndx;
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#if defined(CONFIG_BUILD_FLAT) || defined(__KERNEL__)
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/* Firstly, free mm_delaylist */
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mm_free_delaylist(heap);
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#endif
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/* Ignore zero-length allocations */
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if (size < 1)
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{
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return NULL;
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}
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/* Adjust the size to account for (1) the size of the allocated node and
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* (2) to make sure that it is an even multiple of our granule size.
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*/
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alignsize = MM_ALIGN_UP(size + SIZEOF_MM_ALLOCNODE);
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DEBUGASSERT(alignsize >= size); /* Check for integer overflow */
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DEBUGASSERT(alignsize >= MM_MIN_CHUNK);
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DEBUGASSERT(alignsize >= SIZEOF_MM_FREENODE);
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/* We need to hold the MM semaphore while we muck with the nodelist. */
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mm_takesemaphore(heap);
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/* Get the location in the node list to start the search. Special case
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* really big allocations
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*/
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if (alignsize >= MM_MAX_CHUNK)
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{
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ndx = MM_NNODES - 1;
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}
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else
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{
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/* Convert the request size into a nodelist index */
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ndx = mm_size2ndx(alignsize);
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}
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/* Search for a large enough chunk in the list of nodes. This list is
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* ordered by size, but will have occasional zero sized nodes as we visit
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* other mm_nodelist[] entries.
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*/
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for (node = heap->mm_nodelist[ndx].flink;
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node && node->size < alignsize;
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node = node->flink)
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{
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DEBUGASSERT(node->blink->flink == node);
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}
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/* If we found a node with non-zero size, then this is one to use. Since
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* the list is ordered, we know that is must be best fitting chunk
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* available.
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*/
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if (node)
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{
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FAR struct mm_freenode_s *remainder;
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FAR struct mm_freenode_s *next;
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size_t remaining;
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/* Remove the node. There must be a predecessor, but there may not be
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* a successor node.
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*/
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DEBUGASSERT(node->blink);
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node->blink->flink = node->flink;
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if (node->flink)
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{
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node->flink->blink = node->blink;
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}
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/* Check if we have to split the free node into one of the allocated
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* size and another smaller freenode. In some cases, the remaining
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* bytes can be smaller (they may be SIZEOF_MM_ALLOCNODE). In that
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* case, we will just carry the few wasted bytes at the end of the
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* allocation.
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*/
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remaining = node->size - alignsize;
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if (remaining >= SIZEOF_MM_FREENODE)
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{
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/* Get a pointer to the next node in physical memory */
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next = (FAR struct mm_freenode_s *)
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(((FAR char *)node) + node->size);
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/* Create the remainder node */
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remainder = (FAR struct mm_freenode_s *)
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(((FAR char *)node) + alignsize);
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remainder->size = remaining;
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remainder->preceding = alignsize;
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/* Adjust the size of the node under consideration */
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node->size = alignsize;
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/* Adjust the 'preceding' size of the (old) next node, preserving
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* the allocated flag.
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*/
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next->preceding = remaining | (next->preceding & MM_ALLOC_BIT);
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/* Add the remainder back into the nodelist */
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mm_addfreechunk(heap, remainder);
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}
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/* Handle the case of an exact size match */
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node->preceding |= MM_ALLOC_BIT;
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ret = (void *)((FAR char *)node + SIZEOF_MM_ALLOCNODE);
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}
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DEBUGASSERT(ret == NULL || mm_heapmember(heap, ret));
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mm_givesemaphore(heap);
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#ifdef CONFIG_MM_FILL_ALLOCATIONS
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if (ret)
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{
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memset(ret, 0xaa, alignsize - SIZEOF_MM_ALLOCNODE);
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}
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#endif
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/* If CONFIG_DEBUG_MM is defined, then output the result of the allocation
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* to the SYSLOG.
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*/
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#ifdef CONFIG_DEBUG_MM
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if (!ret)
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{
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mwarn("WARNING: Allocation failed, size %d\n", alignsize);
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}
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else
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{
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minfo("Allocated %p, size %d\n", ret, alignsize);
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}
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#endif
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return ret;
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}
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