lib: add idr_remove_all

[net-next-2.6.git] / lib / idr.c

diff --git a/lib/idr.c b/lib/idr.c
index d29da6159dae0637f5da6042c369ec609207b7de..5ca67b3cfd35ba3243badf0fc50371c299c961fd 100644 (file)
--- a/lib/idr.c
+++ b/lib/idr.c
@@ -390,6 +390,53 @@ void idr_remove(struct idr *idp, int id)
 }
 EXPORT_SYMBOL(idr_remove);
 
+/**
+ * idr_remove_all - remove all ids from the given idr tree
+ * @idp: idr handle
+ *
+ * idr_destroy() only frees up unused, cached idp_layers, but this
+ * function will remove all id mappings and leave all idp_layers
+ * unused.
+ *
+ * A typical clean-up sequence for objects stored in an idr tree, will
+ * use idr_for_each() to free all objects, if necessay, then
+ * idr_remove_all() to remove all ids, and idr_destroy() to free
+ * up the cached idr_layers.
+ */
+void idr_remove_all(struct idr *idp)
+{
+       int n, id, max, error = 0;
+       struct idr_layer *p;
+       struct idr_layer *pa[MAX_LEVEL];
+       struct idr_layer **paa = &pa[0];
+
+       n = idp->layers * IDR_BITS;
+       p = idp->top;
+       max = 1 << n;
+
+       id = 0;
+       while (id < max && !error) {
+               while (n > IDR_BITS && p) {
+                       n -= IDR_BITS;
+                       *paa++ = p;
+                       p = p->ary[(id >> n) & IDR_MASK];
+               }
+
+               id += 1 << n;
+               while (n < fls(id)) {
+                       if (p) {
+                               memset(p, 0, sizeof *p);
+                               free_layer(idp, p);
+                       }
+                       n += IDR_BITS;
+                       p = *--paa;
+               }
+       }
+       idp->top = NULL;
+       idp->layers = 0;
+}
+EXPORT_SYMBOL(idr_remove_all);
+
 /**
  * idr_destroy - release all cached layers within an idr tree
  * idp: idr handle