On Thu, 2011-02-24 at 10:36 +1100, Bruce Evans wrote:
>
> I would cast operand(s) in the expression as necessary to prevent overflow
> of subexpressions. vm_pindex_t would work, but I prefer to use a type
> related to the subexpressions. Not sure what that is. Maybe just
> uintmax_t for safety (even that is not safe if the subexpressions have
> large values). So:
>
> (uintmax_t)swap_bcount * SWAP_META_PAGES * n / mumble.
Following Alan's suggestion, I've attached an updated patch which uses a
cast to u_long and returns long.
--
Bruce Cran
Index: vm_map.h
===================================================================
--- vm_map.h (revision 219050)
+++ vm_map.h (working copy)
@@ -380,6 +380,6 @@
int flags);
int vm_map_wire(vm_map_t map, vm_offset_t start, vm_offset_t end,
int flags);
-vm_offset_t vmspace_swap_count(struct vmspace *vmspace);
+long vmspace_swap_count(struct vmspace *vmspace);
#endif /* _KERNEL */
#endif /* _VM_MAP_ */
Index: swap_pager.c
===================================================================
--- swap_pager.c (revision 219050)
+++ swap_pager.c (working copy)
@@ -2420,13 +2420,13 @@
* if the VM object has any swap use at all the associated map entries
* count for at least 1 swap page.
*/
-vm_offset_t
+long
vmspace_swap_count(struct vmspace *vmspace)
{
vm_map_t map;
vm_map_entry_t cur;
vm_object_t object;
- vm_offset_t count, n;
+ long count, n;
map = &vmspace->vm_map;
count = 0;
@@ -2438,7 +2438,7 @@
if (object->type == OBJT_SWAP &&
object->un_pager.swp.swp_bcount != 0) {
n = (cur->end - cur->start) / PAGE_SIZE;
- count += object->un_pager.swp.swp_bcount *
+ count += (u_long)object->un_pager.swp.swp_bcount *
SWAP_META_PAGES * n / object->size + 1;
}
VM_OBJECT_UNLOCK(object);
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