rbtree: add rbtree_postorder_for_each_entry_safe() helper
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> Reviewed-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Cc: David Woodhouse <David.Woodhouse@intel.com> Cc: Rik van Riel <riel@redhat.com> Cc: Michel Lespinasse <walken@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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@ -85,4 +85,22 @@ static inline void rb_link_node(struct rb_node * node, struct rb_node * parent,
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*rb_link = node;
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*rb_link = node;
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}
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}
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/**
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* rbtree_postorder_for_each_entry_safe - iterate over rb_root in post order of
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* given type safe against removal of rb_node entry
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*
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* @pos: the 'type *' to use as a loop cursor.
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* @n: another 'type *' to use as temporary storage
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* @root: 'rb_root *' of the rbtree.
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* @field: the name of the rb_node field within 'type'.
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*/
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#define rbtree_postorder_for_each_entry_safe(pos, n, root, field) \
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for (pos = rb_entry(rb_first_postorder(root), typeof(*pos), field),\
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n = rb_entry(rb_next_postorder(&pos->field), \
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typeof(*pos), field); \
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&pos->field; \
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pos = n, \
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n = rb_entry(rb_next_postorder(&pos->field), \
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typeof(*pos), field))
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#endif /* _LINUX_RBTREE_H */
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#endif /* _LINUX_RBTREE_H */
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