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Diffstat (limited to 'lib/idr.c')
-rw-r--r--lib/idr.c22
1 files changed, 19 insertions, 3 deletions
diff --git a/lib/idr.c b/lib/idr.c
index e728c7fccc4..1c4f9281f41 100644
--- a/lib/idr.c
+++ b/lib/idr.c
@@ -185,6 +185,7 @@ static int sub_alloc(struct idr *idp, int *starting_id, struct idr_layer **pa)
new = get_from_free_list(idp);
if (!new)
return -1;
+ new->layer = l-1;
rcu_assign_pointer(p->ary[m], new);
p->count++;
}
@@ -210,6 +211,7 @@ build_up:
if (unlikely(!p)) {
if (!(p = get_from_free_list(idp)))
return -1;
+ p->layer = 0;
layers = 1;
}
/*
@@ -218,8 +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
@@ -237,6 +245,7 @@ build_up:
}
new->ary[0] = p;
new->count = 1;
+ new->layer = layers-1;
if (p->bitmap == IDR_FULL)
__set_bit(0, &new->bitmap);
p = new;
@@ -493,17 +502,21 @@ void *idr_find(struct idr *idp, int id)
int n;
struct idr_layer *p;
- n = idp->layers * IDR_BITS;
p = rcu_dereference(idp->top);
+ if (!p)
+ return NULL;
+ n = (p->layer+1) * IDR_BITS;
/* Mask off upper bits we don't use for the search. */
id &= MAX_ID_MASK;
if (id >= (1 << n))
return NULL;
+ BUG_ON(n == 0);
while (n > 0 && p) {
n -= IDR_BITS;
+ BUG_ON(n != p->layer*IDR_BITS);
p = rcu_dereference(p->ary[(id >> n) & IDR_MASK]);
}
return((void *)p);
@@ -582,8 +595,11 @@ void *idr_replace(struct idr *idp, void *ptr, int id)
int n;
struct idr_layer *p, *old_p;
- n = idp->layers * IDR_BITS;
p = idp->top;
+ if (!p)
+ return ERR_PTR(-EINVAL);
+
+ n = (p->layer+1) * IDR_BITS;
id &= MAX_ID_MASK;