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| author | Manfred Spraul <manfred@colorfullife.com> | 2008-12-10 18:17:06 +0100 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2008-12-10 13:34:33 -0800 |
| commit | 711a49a07f84f914aac26a52143f6e7526571143 (patch) | |
| tree | 3ca4f774f868c1884bc6dc416ea68aa7b8666ef7 /lib/idr.c | |
| parent | c7f8d6f6b5d121e5f7408119661ca29fc4661c10 (diff) | |
| download | lwn-711a49a07f84f914aac26a52143f6e7526571143.tar.gz lwn-711a49a07f84f914aac26a52143f6e7526571143.zip | |
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 <manfred@colorfullife.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'lib/idr.c')
| -rw-r--r-- | lib/idr.c | 8 |
1 files changed, 7 insertions, 1 deletions
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 @@ build_up: */ 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 |