On Sun, Jun 04, 2006 at 02:11:05AM -0700, Andrew Morton wrote:
> On Sun, 4 Jun 2006 16:45:48 +0800
> Wu Fengguang <[email protected]> wrote:
>
> > Andrew, this small patch makes the radixtree tester program from
> > http://www.zip.com.au/~akpm/linux/patches/stuff/rtth.tar.gz
> > run OK, with the latest radix tree code in linux-2.6.17-rc5-mm2.
> >
> > It regulates the return value to 0/1 for functions
> > radix_tree_tag_get() and radix_tree_tagged().
> >
>
> Well yes. But it slows down the kernel. It would be better to fix rtth.
OK. I'll send an updated patch to directly fix the for-rtth radix_tree_tag_get().
> > ---
> >
> > --- linux.orig/lib/radix-tree.c
> > +++ linux/lib/radix-tree.c
> > @@ -156,7 +156,7 @@ static inline void tag_clear(struct radi
> > static inline int tag_get(struct radix_tree_node *node, unsigned int tag,
> > int offset)
> > {
> > - return test_bit(offset, node->tags[tag]);
> > + return !! test_bit(offset, node->tags[tag]);
> > }
>
> test_bit() is (sadly) defined to return 0 or 1. Did this really make a difference?
Interesting. I got the following gdb outputs. Note that tag_get()
returns -1 and root_tag_get() returns 1048576.
(gdb) n
399 while (height > 0) {
(gdb) n
402 offset = (index >> shift) & RADIX_TREE_MAP_MASK;
(gdb)
403 if (!tag_get(slot, tag, offset))
(gdb)
404 tag_set(slot, tag, offset);
(gdb) p tag_get(slot, tag, offset)
$14 = 0
(gdb) n
405 slot = slot->slots[offset];
(gdb) p tag_get(slot, tag, offset)
$15 = -1
(gdb) n
406 BUG_ON(slot == NULL);
(gdb) n
407 shift -= RADIX_TREE_MAP_SHIFT;
(gdb) n
408 height--;
(gdb) n
399 while (height > 0) {
(gdb) n
412 if (slot && !root_tag_get(root, tag))
(gdb) p root_tag_get(root, tag)
$16 = 0
(gdb) n
413 root_tag_set(root, tag);
(gdb) n
415 return slot;
(gdb) p root_tag_get(root, tag)
$17 = 1048576
> > static inline void root_tag_set(struct radix_tree_root *root, unsigned int tag)
> > @@ -177,7 +177,7 @@ static inline void root_tag_clear_all(st
> >
> > static inline int root_tag_get(struct radix_tree_root *root, unsigned int tag)
> > {
> > - return root->gfp_mask & (1 << (tag + __GFP_BITS_SHIFT));
> > + return !! (root->gfp_mask & (1 << (tag + __GFP_BITS_SHIFT)));
> > }
> >
>
-
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