Hello Dan,
On Mon, Apr 04, 2016 at 11:39:52PM +0300, Dan Carpenter wrote:
> Hello Minchan Kim,
>
> The patch 9a0346061ab8: "zsmalloc: zs_compact refactoring" from Apr
> 2, 2016, leads to the following static checker warning:
>
> mm/zsmalloc.c:1851 handle_from_obj()
> warn: bit shifter 'OBJ_ALLOCATED_TAG' used for logical '&'
>
> mm/zsmalloc.c
> 1622 static unsigned long obj_malloc(struct size_class *class,
> 1623 struct page *first_page, unsigned long handle)
> 1624 {
> 1625 unsigned long obj;
> 1626 struct link_free *link;
> 1627
> 1628 struct page *m_page;
> 1629 unsigned long m_offset;
> 1630 void *vaddr;
> 1631
> 1632 obj = get_freeobj(first_page);
> 1633 objidx_to_page_and_offset(class, first_page, obj,
> 1634 &m_page, &m_offset);
> 1635
> 1636 vaddr = kmap_atomic(m_page);
> 1637 link = (struct link_free *)vaddr + m_offset / sizeof(*link);
> 1638 set_freeobj(first_page, link->next >> OBJ_ALLOCATED_TAG);
> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> OBJ_ALLOCATED_TAG is 1. Here it's used as a shifter.
>
> 1639 if (!class->huge)
> 1640 /* record handle in the header of allocated chunk */
> 1641 link->handle = handle | OBJ_ALLOCATED_TAG;
>
> Here it's a bit mask. It's sort of confusing to re-use it like this.
> It's done through out the file.
I will send clean up patch.
Thanks.
>
> 1642 else
> 1643 /* record handle in first_page->private */
> 1644 set_page_private(first_page, handle | OBJ_ALLOCATED_TAG);
> 1645 kunmap_atomic(vaddr);
> 1646 mod_zspage_inuse(first_page, 1);
> 1647
> 1648 obj = location_to_obj(m_page, obj);
> 1649
> 1650 return obj;
> 1651 }
>
> regards,
> dan carpenter
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