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SubjectRe: [PATCH 6/8] fs/ext3: use rbtree postorder iteration helper instead of opencoding
On Mon 04-11-13 15:26:38, Jan Kara wrote:
> On Fri 01-11-13 15:38:50, Cody P Schafer wrote:
> > Use rbtree_postorder_for_each_entry_safe() to destroy the rbtree instead
> > of opencoding an alternate postorder iteration that modifies the tree
> Thanks. I've merged the patch into my tree.
Hum, except that the kernel oopses with this patch. And I think the
problem is in rbtree_postorder_for_each_entry_safe(). How are those tests
for NULL supposed to work? For example if the tree is empty, 'pos' will be
NULL and you'll call rb_next_postorder(&NULL->field) which is pretty much
guaranteed to oops if 'field' doesn't have offset 0 in the structure...

Honza

> > Signed-off-by: Cody P Schafer <cody@linux.vnet.ibm.com>
> > ---
> > fs/ext3/dir.c | 36 +++++-------------------------------
> > 1 file changed, 5 insertions(+), 31 deletions(-)
> >
> > diff --git a/fs/ext3/dir.c b/fs/ext3/dir.c
> > index bafdd48..a331ad1 100644
> > --- a/fs/ext3/dir.c
> > +++ b/fs/ext3/dir.c
> > @@ -309,43 +309,17 @@ struct fname {
> > */
> > static void free_rb_tree_fname(struct rb_root *root)
> > {
> > - struct rb_node *n = root->rb_node;
> > - struct rb_node *parent;
> > - struct fname *fname;
> > -
> > - while (n) {
> > - /* Do the node's children first */
> > - if (n->rb_left) {
> > - n = n->rb_left;
> > - continue;
> > - }
> > - if (n->rb_right) {
> > - n = n->rb_right;
> > - continue;
> > - }
> > - /*
> > - * The node has no children; free it, and then zero
> > - * out parent's link to it. Finally go to the
> > - * beginning of the loop and try to free the parent
> > - * node.
> > - */
> > - parent = rb_parent(n);
> > - fname = rb_entry(n, struct fname, rb_hash);
> > + struct fname *fname, *next;
> > +
> > + rbtree_postorder_for_each_entry_safe(fname, next, root, rb_hash)
> > while (fname) {
> > struct fname * old = fname;
> > fname = fname->next;
> > kfree (old);
> > }
> > - if (!parent)
> > - *root = RB_ROOT;
> > - else if (parent->rb_left == n)
> > - parent->rb_left = NULL;
> > - else if (parent->rb_right == n)
> > - parent->rb_right = NULL;
> > - n = parent;
> > - }
> > -}
> >
> > + *root = RB_ROOT;
> > +}
> >
> > static struct dir_private_info *ext3_htree_create_dir_info(struct file *filp,
> > loff_t pos)
> > --
> > 1.8.4.2
> >
> --
> Jan Kara <jack@suse.cz>
> SUSE Labs, CR
--
Jan Kara <jack@suse.cz>
SUSE Labs, CR


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