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Diffstat (limited to 'include/linux/rculist_nulls.h')
-rw-r--r--include/linux/rculist_nulls.h39
1 files changed, 39 insertions, 0 deletions
diff --git a/include/linux/rculist_nulls.h b/include/linux/rculist_nulls.h
index 1c33dd7da4a7..4ae95f7e8597 100644
--- a/include/linux/rculist_nulls.h
+++ b/include/linux/rculist_nulls.h
@@ -98,6 +98,45 @@ static inline void hlist_nulls_add_head_rcu(struct hlist_nulls_node *n,
if (!is_a_nulls(first))
first->pprev = &n->next;
}
+
+/**
+ * hlist_nulls_add_tail_rcu
+ * @n: the element to add to the hash list.
+ * @h: the list to add to.
+ *
+ * Description:
+ * Adds the specified element to the end of the specified hlist_nulls,
+ * while permitting racing traversals. NOTE: tail insertion requires
+ * list traversal.
+ *
+ * The caller must take whatever precautions are necessary
+ * (such as holding appropriate locks) to avoid racing
+ * with another list-mutation primitive, such as hlist_nulls_add_head_rcu()
+ * or hlist_nulls_del_rcu(), running on this same list.
+ * However, it is perfectly legal to run concurrently with
+ * the _rcu list-traversal primitives, such as
+ * hlist_nulls_for_each_entry_rcu(), used to prevent memory-consistency
+ * problems on Alpha CPUs. Regardless of the type of CPU, the
+ * list-traversal primitive must be guarded by rcu_read_lock().
+ */
+static inline void hlist_nulls_add_tail_rcu(struct hlist_nulls_node *n,
+ struct hlist_nulls_head *h)
+{
+ struct hlist_nulls_node *i, *last = NULL;
+
+ for (i = hlist_nulls_first_rcu(h); !is_a_nulls(i);
+ i = hlist_nulls_next_rcu(i))
+ last = i;
+
+ if (last) {
+ n->next = last->next;
+ n->pprev = &last->next;
+ rcu_assign_pointer(hlist_nulls_next_rcu(last), n);
+ } else {
+ hlist_nulls_add_head_rcu(n, h);
+ }
+}
+
/**
* hlist_nulls_for_each_entry_rcu - iterate over rcu list of given type
* @tpos: the type * to use as a loop cursor.