From 711a49a07f84f914aac26a52143f6e7526571143 Mon Sep 17 00:00:00 2001 From: Manfred Spraul Date: Wed, 10 Dec 2008 18:17:06 +0100 Subject: [PATCH] lib/idr.c: Fix bug introduced by RCU fix The last patch to lib/idr.c caused a bug if idr_get_new_above() was called on an empty idr. Usually, nodes stay on the same layer. New layers are added to the top of the tree. The exception is idr_get_new_above() on an empty tree: In this case, the new root node is first added on layer 0, then moved upwards. p->layer was not updated. As usual: You shall never rely on the source code comments, they will only mislead you. Signed-off-by: Manfred Spraul Signed-off-by: Linus Torvalds --- lib/idr.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/lib/idr.c b/lib/idr.c index 7a785a0c2ea0..1c4f9281f412 100644 --- a/lib/idr.c +++ b/lib/idr.c @@ -220,8 +220,14 @@ static int idr_get_empty_slot(struct idr *idp, int starting_id, */ while ((layers < (MAX_LEVEL - 1)) && (id >= (1 << (layers*IDR_BITS)))) { layers++; - if (!p->count) + if (!p->count) { + /* special case: if the tree is currently empty, + * then we grow the tree by moving the top node + * upwards. + */ + p->layer++; continue; + } if (!(new = get_from_free_list(idp))) { /* * The allocation failed. If we built part of