idr: make idr_find rcu-safe

[linux-2.6-omap-h63xx.git] / lib / idr.c

diff --git a/lib/idr.c b/lib/idr.c
index 44ab3b2a4eba44cde95972d38687dcc427607b4b..21e12af1f231232a44197261c242b547874885df 100644 (file)
--- a/lib/idr.c
+++ b/lib/idr.c
@@ -456,7 +456,8 @@ EXPORT_SYMBOL(idr_destroy);
  * return indicates that @id is not valid or you passed %NULL in
  * idr_get_new().
  *
- * The caller must serialize idr_find() vs idr_get_new() and idr_remove().
+ * This function can be called under rcu_read_lock(), given that the leaf
+ * pointers lifetimes are correctly managed.
  */
 void *idr_find(struct idr *idp, int id)
 {
@@ -464,7 +465,7 @@ void *idr_find(struct idr *idp, int id)
        struct idr_layer *p;
 
        n = idp->layers * IDR_BITS;
-       p = idp->top;
+       p = rcu_dereference(idp->top);
 
        /* Mask off upper bits we don't use for the search. */
        id &= MAX_ID_MASK;
@@ -474,7 +475,7 @@ void *idr_find(struct idr *idp, int id)
 
        while (n > 0 && p) {
                n -= IDR_BITS;
-               p = p->ary[(id >> n) & IDR_MASK];
+               p = rcu_dereference(p->ary[(id >> n) & IDR_MASK]);
        }
        return((void *)p);
 }
@@ -507,7 +508,7 @@ int idr_for_each(struct idr *idp,
        struct idr_layer **paa = &pa[0];
 
        n = idp->layers * IDR_BITS;
-       p = idp->top;
+       p = rcu_dereference(idp->top);
        max = 1 << n;
 
        id = 0;
@@ -515,7 +516,7 @@ int idr_for_each(struct idr *idp,
                while (n > 0 && p) {
                        n -= IDR_BITS;
                        *paa++ = p;
-                       p = p->ary[(id >> n) & IDR_MASK];
+                       p = rcu_dereference(p->ary[(id >> n) & IDR_MASK]);
                }
 
                if (p) {