Put a magic number into the allocator chunks.

Use that as an internal invariant.  Free chunks must contain
the magic number.

diff --git a/lib/libbmk_core/pgalloc.c b/lib/libbmk_core/pgalloc.c
index b1667c7bbbe83dc114991be30e597031561ccba0..04588e2681069dd9a5f73f248a89916d153cd91b 100644 (file)
--- a/lib/libbmk_core/pgalloc.c
+++ b/lib/libbmk_core/pgalloc.c
@@ -144,12 +144,22 @@ map_free(void *virt, unsigned long nr_pages)
  * BINARY BUDDY ALLOCATOR
  */
 
+#define CHUNKMAGIC 0x11020217
 struct chunk_head {
        struct chunk_head  *next;
        struct chunk_head **pprev;
        int level;
+       int magic;
 };
 
+static int
+chunklevel(struct chunk_head *ch)
+{
+
+       bmk_assert(ch->magic == CHUNKMAGIC);
+       return ch->level;
+}
+
 /* Linked lists of free chunks of different powers-of-two in size. */
 #define FREELIST_SIZE ((sizeof(void*)<<3)-BMK_PCPU_PAGE_SHIFT)
 static struct chunk_head **free_head;
@@ -306,6 +316,7 @@ bmk_pgalloc_loadmem(unsigned long min, unsigned long max)
                ch->next        = free_head[i];
                ch->pprev       = &free_head[i];
                ch->next->pprev = &ch->next;
+               ch->magic       = CHUNKMAGIC;
                free_head[i]    = ch;
        }
 }
@@ -332,6 +343,9 @@ bmk_pgalloc(int order)
        free_head[i] = alloc_ch->next;
        alloc_ch->next->pprev = alloc_ch->pprev;
 
+       bmk_assert(alloc_ch->magic == CHUNKMAGIC);
+       alloc_ch->magic = 0;
+
        /* We may have to break the chunk a number of times. */
        while (i != (unsigned)order) {
                /* Split into two equal parts. */
@@ -342,6 +356,7 @@ bmk_pgalloc(int order)
                spare_ch->level = i;
                spare_ch->next  = free_head[i];
                spare_ch->pprev = &free_head[i];
+               spare_ch->magic = CHUNKMAGIC;
 
                /* Link in the spare chunk. */
                spare_ch->next->pprev = &spare_ch->next;
@@ -379,19 +394,25 @@ bmk_pgfree(void *pointer, int order)
                        to_merge_ch = addr2ch(freed_ch, -mask);
                        if (!addr_is_managed(to_merge_ch) \
                            || allocated_in_map(to_merge_ch)
-                           || to_merge_ch->level != order)
+                           || chunklevel(to_merge_ch) != order)
                                break;
 
+                       freed_ch->magic = 0;
+
                        /* Merge with predecessor */
                        freed_ch = to_merge_ch;
                } else {
                        to_merge_ch = addr2ch(freed_ch, mask);
                        if (!addr_is_managed(to_merge_ch)
                            || allocated_in_map(to_merge_ch)
-                           || to_merge_ch->level != order)
+                           || chunklevel(to_merge_ch) != order)
                                break;
+
+                       freed_ch->magic = 0;
                }
 
+               to_merge_ch->magic = 0;
+
                /* We are commited to merging, unlink the chunk */
                *(to_merge_ch->pprev) = to_merge_ch->next;
                to_merge_ch->next->pprev = to_merge_ch->pprev;
@@ -403,6 +424,7 @@ bmk_pgfree(void *pointer, int order)
        freed_ch->level = order;
        freed_ch->next  = free_head[order];
        freed_ch->pprev = &free_head[order];
+       freed_ch->magic = CHUNKMAGIC;
 
        freed_ch->next->pprev = &freed_ch->next;
        free_head[order] = freed_ch;