rbtree: handle 1-child recoloring in rb_erase() instead of rb_erase_color()
authorMichel Lespinasse <walken@google.com>
Mon, 8 Oct 2012 23:31:11 +0000 (16:31 -0700)
committerLinus Torvalds <torvalds@linux-foundation.org>
Tue, 9 Oct 2012 07:22:37 +0000 (16:22 +0900)
commit46b6135a7402ac23c5b25f2bd79b03bab8f98278
tree8430c191a455b1ff48c62229731ded4cbc71a9a1
parent60670b8034d6e2ba860af79c9379b7788d09db73
rbtree: handle 1-child recoloring in rb_erase() instead of rb_erase_color()

An interesting observation for rb_erase() is that when a node has
exactly one child, the node must be black and the child must be red.
An interesting consequence is that removing such a node can be done by
simply replacing it with its child and making the child black,
which we can do efficiently in rb_erase(). __rb_erase_color() then
only needs to handle the no-childs case and can be modified accordingly.

Signed-off-by: Michel Lespinasse <walken@google.com>
Acked-by: Rik van Riel <riel@redhat.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
lib/rbtree.c