Fix a bug in heap_grow() that would cause the heap list to be bent into a loop

diff --git a/kernel/arch/heap.c b/kernel/arch/heap.c
index fa83b368ed2cac096ad4561d932bfc89dd2e81d9..eac7d5df4996cde23314b3f2c9dbaba6169e3062 100644 (file)
--- a/kernel/arch/heap.c
+++ b/kernel/arch/heap.c
@@ -16,6 +16,7 @@
  * along with Corax.  If not, see <http://www.gnu.org/licenses/>.
  */
 
+#include <corax/errno.h>
 #include <debug.h>
 #include "paging.h"
 #include "heap.h"
@@ -79,16 +80,23 @@ void heap_init(void *base, u32_t size)
 
 static int heap_grow(const u32_t size)
 {
-       struct heap_node *cur;
+       struct heap_node *last;
        struct heap_node *new;
        u32_t sreq;
+       u32_t allocated;
        int ret_val;
 
        new = NULL;
-       ret_val = 1;
+       ret_val = -ENOMEM;
+       allocated = 0;
 
-       /* add more pages to the pagedir */
+       last = (struct heap_node*)_kheap.h_base;
+
+       while(last->hn_next) {
+               last = last->hn_next;
+       }
 
+       /* add more pages to the pagedir */
        for(sreq = ALIGN(size << 2, PAGE_SIZE); sreq > 0; sreq -= PAGE_SIZE) {
                void *addr;
 
@@ -98,27 +106,35 @@ static int heap_grow(const u32_t size)
                        break;
                }
 
-               if(!new) {
-                       new = (struct heap_node*)addr;
-                       cur = (struct heap_node*)_kheap.h_base;
+               if(!(last->hn_flags & FLAG_USED)) {
+                       /* add memory to the last, unused node */
+                       last->hn_size += PAGE_SIZE;
+                       allocated += PAGE_SIZE;
+               } else {
+                       /* add memory to a new node at the end */
 
-                       new->hn_size = PAGE_SIZE - sizeof(*new);
-                       new->hn_flags = 0;
-                       new->hn_next = NULL;
+                       if(!new) {
+                               /* create the new node */
+                               new = (struct heap_node*)addr;
 
-                       /* add new node to the end of the heap */
-                       while(cur->hn_next) {
-                               cur = cur->hn_next;
-                       }
+                               new->hn_next = NULL;
+                               last->hn_next = new;
 
-                       cur->hn_next = new;
-               } else {
-                       new->hn_size += PAGE_SIZE;
+                               new->hn_size = PAGE_SIZE - sizeof(*new);
+                               new->hn_flags = 0;
+                       } else {
+                               /* node has already been created - expand it */
+                               new->hn_size += PAGE_SIZE;
+                               allocated += PAGE_SIZE;
+                       }
                }
        }
 
-       if(new) {
-               _kheap.h_size += new->hn_size;
+       _kheap.h_size += allocated;
+       _kheap.h_free += allocated;
+
+       /* return success if we allocated enough to satisfy the request */
+       if(size <= allocated) {
                ret_val = 0;
        }
 
@@ -136,6 +152,8 @@ void* kmalloc(u32_t size)
                heap_grow(size);
        }
 
+       heap_debug();
+
        for(cur = (struct heap_node*)_kheap.h_base;
                cur;
                cur = cur->hn_next) {
@@ -158,7 +176,13 @@ void* kmalloc(u32_t size)
 
                        new = (struct heap_node*)(ret_val + size);
 
-                       new->hn_size = cur->hn_size - size - (2 * sizeof(*new));
+                       /*
+                        *       |<---       cur->hn_size      --->|
+                        * +-----+----------+-----+----------------+--------------+
+                        * | cur | < size > | new | <new->hn_size> | cur->hn_next |
+                        * +-----+----------+-----+----------------+--------------+
+                        */
+                       new->hn_size = cur->hn_size - size - sizeof(*new);
                        new->hn_next = cur->hn_next;
                        new->hn_flags = 0;