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* Set freed memory to 0xdeadbeef before returning it to page. This allows us to

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not hold the bin lock while setting and only protect the actual freeing. May
  reduce bin lock contention a little bit.
* Tiny optimization for force-clearing 0xdeadbeef. Do it after setting to 0xcc,
  so that it's less likely we have to do it.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@32473 a95241bf-73f2-0310-859d-f6bbb57e9c96
This commit is contained in:
Michael Lotz 2009-08-17 17:25:24 +00:00
parent dacf06e665
commit 73c035dc11
1 changed files with 14 additions and 19 deletions
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33
src/system/kernel/heap.cpp
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@ -1433,6 +1433,10 @@ heap_memalign(heap_allocator *heap, size_t alignment, size_t size)
if (address == NULL)
return address;
#if PARANOID_KERNEL_MALLOC
memset(address, 0xcc, size);
#endif
#if PARANOID_KERNEL_FREE
// make sure 0xdeadbeef is cleared if we do not overwrite the memory
// and the user does not clear it
@ -1440,10 +1444,6 @@ heap_memalign(heap_allocator *heap, size_t alignment, size_t size)
((uint32 *)address)[1] = 0xcccccccc;
#endif
#if PARANOID_KERNEL_MALLOC
memset(address, 0xcc, size);
#endif
return address;
}
@ -1495,19 +1495,12 @@ heap_free(heap_allocator *heap, void *address)
if (page->bin_index < heap->bin_count) {
// small allocation
heap_bin *bin = &heap->bins[page->bin_index];
MutexLocker binLocker(bin->lock);
if (((addr_t)address - area->base - page->index
* heap->page_size) % bin->element_size != 0) {
panic("free(): passed invalid pointer %p supposed to be in bin for "
"element size %ld\n", address, bin->element_size);
return B_ERROR;
}
#if PARANOID_KERNEL_FREE
if (((uint32 *)address)[1] == 0xdeadbeef) {
// This block looks like it was freed already, walk the free list
// on this page to make sure this address doesn't exist.
MutexLocker binLocker(bin->lock);
for (addr_t *temp = page->free_list; temp != NULL;
temp = (addr_t *)*temp) {
if (temp == address) {
@ -1518,19 +1511,21 @@ heap_free(heap_allocator *heap, void *address)
}
}
uint32 *dead = (uint32 *)address;
if (bin->element_size % 4 != 0) {
panic("free(): didn't expect a bin element size that is not a "
"multiple of 4\n");
return B_ERROR;
}
// the first 4 bytes are overwritten with the next free list pointer
// later
uint32 *dead = (uint32 *)address;
for (uint32 i = 1; i < bin->element_size / sizeof(uint32); i++)
dead[i] = 0xdeadbeef;
#endif
MutexLocker binLocker(bin->lock);
if (((addr_t)address - area->base - page->index
* heap->page_size) % bin->element_size != 0) {
panic("free(): passed invalid pointer %p supposed to be in bin for "
"element size %ld\n", address, bin->element_size);
return B_ERROR;
}
// add the address to the page free list
*(addr_t *)address = (addr_t)page->free_list;
page->free_list = (addr_t *)address;