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    Subject[PATCH 2/5] rbtree: add rbtree_postorder_for_each_entry_safe() helper
    Date
    Because deletion (of the entire tree) is a relatively common use of the
    rbtree_postorder iteration, and because doing it safely means fiddling
    with temporary storage, provide a helper to simplify postorder rbtree
    iteration.

    Signed-off-by: Cody P Schafer <cody@linux.vnet.ibm.com>
    ---
    include/linux/rbtree.h | 17 +++++++++++++++++
    1 file changed, 17 insertions(+)

    diff --git a/include/linux/rbtree.h b/include/linux/rbtree.h
    index 2879e96..64ab98b 100644
    --- a/include/linux/rbtree.h
    +++ b/include/linux/rbtree.h
    @@ -85,4 +85,21 @@ static inline void rb_link_node(struct rb_node * node, struct rb_node * parent,
    *rb_link = node;
    }

    +/**
    + * rbtree_postorder_for_each_entry_safe - iterate over rb_root in post order of
    + * given type safe against removal of rb_node entry
    + *
    + * @pos: the 'type *' to use as a loop cursor.
    + * @n: another 'type *' to use as temporary storage
    + * @root: 'rb_root *' of the rbtree.
    + * @field: the name of the rb_node field within 'type'.
    + */
    +#define rbtree_postorder_for_each_entry_safe(pos, n, root, field) \
    + for (pos = rb_entry(rb_first_postorder(root), typeof(*pos), field),\
    + n = rb_entry(rb_next_postorder(&pos->field), \
    + typeof(*pos), field); \
    + &pos->field; \
    + pos = n, \
    + n = rb_entry(rb_next_postorder(&pos->field), typeof(*pos), field))
    +
    #endif /* _LINUX_RBTREE_H */
    --
    1.8.3.4


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