Re: [Xen-devel] [PATCH v6 14/16] rbtree: handle 1-child recoloring in rb_erase() instead of rb_erase_color()

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 21.11.17 at 16:20, <kpraveen.lkml@xxxxxxxxx> wrote:
> From: Michel Lespinasse <walken@xxxxxxxxxx>
> 
> 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@xxxxxxxxxx>
> Acked-by: Rik van Riel <riel@xxxxxxxxxx>
> Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
> Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx>
> Cc: David Woodhouse <dwmw2@xxxxxxxxxxxxx>
> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
> [Linux commit 46b6135a7402ac23c5b25f2bd79b03bab8f98278]
> 
> Ported to Xen.
> 
> Signed-off-by: Praveen Kumar <kpraveen.lkml@xxxxxxxxx>

Acked-by: Jan Beulich <jbeulich@xxxxxxxx>



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