1 files changed, 23 insertions, 13 deletions

diff --git a/lib/idr.c b/lib/idr.c
index e728c7fccc4d..c11c5765cdef 100644
--- a/lib/idr.c
+++ b/lib/idr.c
@@ -121,7 +121,7 @@ int idr_pre_get(struct idr *idp, gfp_t gfp_mask)
 {
 	while (idp->id_free_cnt < IDR_FREE_MAX) {
 		struct idr_layer *new;
-		new = kmem_cache_alloc(idr_layer_cache, gfp_mask);
+		new = kmem_cache_zalloc(idr_layer_cache, gfp_mask);
 		if (new == NULL)
 			return (0);
 		move_to_free_list(idp, new);
@@ -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;
@@ -283,7 +292,7 @@ static int idr_get_new_above_int(struct idr *idp, void *ptr, int starting_id)
  * and go back to the idr_pre_get() call.  If the idr is full, it will
  * return -ENOSPC.
  *
- * @id returns a value in the range 0 ... 0x7fffffff
+ * @id returns a value in the range @starting_id ... 0x7fffffff
  */
 int idr_get_new_above(struct idr *idp, void *ptr, int starting_id, int *id)
 {
@@ -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;
 
@@ -607,16 +623,10 @@ void *idr_replace(struct idr *idp, void *ptr, int id)
 }
 EXPORT_SYMBOL(idr_replace);
 
-static void idr_cache_ctor(void *idr_layer)
-{
-	memset(idr_layer, 0, sizeof(struct idr_layer));
-}
-
 void __init idr_init_cache(void)
 {
 	idr_layer_cache = kmem_cache_create("idr_layer_cache",
-				sizeof(struct idr_layer), 0, SLAB_PANIC,
-				idr_cache_ctor);
+				sizeof(struct idr_layer), 0, SLAB_PANIC, NULL);
 }
 
 /**
@@ -707,7 +717,7 @@ EXPORT_SYMBOL(ida_pre_get);
  * and go back to the ida_pre_get() call.  If the ida is full, it will
  * return -ENOSPC.
  *
- * @p_id returns a value in the range 0 ... 0x7fffffff.
+ * @p_id returns a value in the range @starting_id ... 0x7fffffff.
  */
 int ida_get_new_above(struct ida *ida, int starting_id, int *p_id)
 {