[PATCH 0/5] Add rbtree postorder iteration functions, runtime tests, and update zswap to use.

From: Cody P Schafer
Date: Fri Jul 26 2013 - 17:15:01 EST

Postorder iteration yields all of a node's children prior to yielding the node
itself, and this particular implementation also avoids examining the leaf links
in a node after that node has been yielded.

In what I expect will be it's most common usage, postorder iteration allows the
deletion of every node in an rbtree without modifying the rbtree nodes (no
_requirement_ that they be nulled) while avoiding referencing child nodes after
they have been "deleted" (most commonly, freed).

I have only updated zswap to use this functionality at this point, but numerous
bits of code (most notably in the filesystem drivers) use a hand rolled
postorder iteration that NULLs child links as it traverses the tree. Each of
those instances could be replaced with this common implementation.

Cody P Schafer (5):
rbtree: add postorder iteration functions.
rbtree: add rbtree_postorder_for_each_entry_safe() helper.
rbtree_test: add test for postorder iteration.
rbtree: allow tests to run as builtin
mm/zswap: use postorder iteration when destroying rbtree

include/linux/rbtree.h | 21 +++++++++++++++++++++
lib/Kconfig.debug | 2 +-
lib/rbtree.c | 40 ++++++++++++++++++++++++++++++++++++++++
lib/rbtree_test.c | 12 ++++++++++++
mm/zswap.c | 15 ++-------------
5 files changed, 76 insertions(+), 14 deletions(-)


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