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lib/idr.c: Fix bug introduced by RCU fix

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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 <manfred@colorfullife.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Manfred Spraul 2008-12-10 18:17:06 +01:00 committed by Linus Torvalds
parent c7f8d6f6b5
commit 711a49a07f
1 changed files with 7 additions and 1 deletions
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lib/idr.c
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@ -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