Use the empty_index field as the allocation_id for large allocations and just

use the index of the first page of the allocation as an id. This removes the
need for separate id generation. This also fixes the possible problem of
multiple large allocations getting the same allocation_id (due to the limited
range of possible ids), which in the worst case (i.e. for adjacent allocations)
could cause pages to be freed that were still in use.

git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@24405 a95241bf-73f2-0310-859d-f6bbb57e9c96

src/system/kernel/heap.cpp

@@ -59,7 +59,7 @@ typedef struct heap_page_s {
 } heap_page;
 
 // used for bin == bin_count allocations
-#define allocation_id free_count
+#define allocation_id empty_index
 
 typedef struct heap_bin_s {
 	uint32		element_size;
@@ -71,7 +71,6 @@ typedef struct heap_allocator_s {
 	addr_t		base;
 	size_t		size;
 	mutex		lock;
-	vint32		large_alloc_id;
 
 	uint32		bin_count;
 	uint32		page_count;
@@ -536,13 +535,6 @@ heap_attach(addr_t base, size_t size, bool postSem)
 }
 
 
-static inline uint32
-heap_next_alloc_id(heap_allocator *heap)
-{
-	return atomic_add(&heap->large_alloc_id, 1) & ((1 << 9) - 1);
-}
-
-
 static inline void
 heap_link_page(heap_page *page, heap_page **list)
 {
@@ -672,7 +664,6 @@ heap_raw_alloc(heap_allocator *heap, size_t size, uint32 binIndex)
 		return NULL;
 	}
 
-	uint32 allocationID = heap_next_alloc_id(heap);
 	uint32 pageCount = (size + B_PAGE_SIZE - 1) / B_PAGE_SIZE;
 	for (uint32 i = first; i < first + pageCount; i++) {
 		heap_page *page = &heap->page_table[i];
@@ -683,7 +674,7 @@ heap_raw_alloc(heap_allocator *heap, size_t size, uint32 binIndex)
 
 		page->next = page->prev = NULL;
 		page->free_list = NULL;
-		page->allocation_id = allocationID;
+		page->allocation_id = (uint16)first;
 	}
 
 #if KERNEL_HEAP_LEAK_CHECK