These changes are the raw update to linux-4.4.6-rt14. Kernel sources

[kvmfornfv.git] / kernel / lib / klist.c

diff --git a/kernel/lib/klist.c b/kernel/lib/klist.c
index 89b485a..0507fa5 100644 (file)
--- a/kernel/lib/klist.c
+++ b/kernel/lib/klist.c
@@ -282,9 +282,9 @@ void klist_iter_init_node(struct klist *k, struct klist_iter *i,
                          struct klist_node *n)
 {
        i->i_klist = k;
-       i->i_cur = n;
-       if (n)
-               kref_get(&n->n_ref);
+       i->i_cur = NULL;
+       if (n && kref_get_unless_zero(&n->n_ref))
+               i->i_cur = n;
 }
 EXPORT_SYMBOL_GPL(klist_iter_init_node);
 
@@ -323,6 +323,47 @@ static struct klist_node *to_klist_node(struct list_head *n)
        return container_of(n, struct klist_node, n_node);
 }
 
+/**
+ * klist_prev - Ante up prev node in list.
+ * @i: Iterator structure.
+ *
+ * First grab list lock. Decrement the reference count of the previous
+ * node, if there was one. Grab the prev node, increment its reference
+ * count, drop the lock, and return that prev node.
+ */
+struct klist_node *klist_prev(struct klist_iter *i)
+{
+       void (*put)(struct klist_node *) = i->i_klist->put;
+       struct klist_node *last = i->i_cur;
+       struct klist_node *prev;
+
+       spin_lock(&i->i_klist->k_lock);
+
+       if (last) {
+               prev = to_klist_node(last->n_node.prev);
+               if (!klist_dec_and_del(last))
+                       put = NULL;
+       } else
+               prev = to_klist_node(i->i_klist->k_list.prev);
+
+       i->i_cur = NULL;
+       while (prev != to_klist_node(&i->i_klist->k_list)) {
+               if (likely(!knode_dead(prev))) {
+                       kref_get(&prev->n_ref);
+                       i->i_cur = prev;
+                       break;
+               }
+               prev = to_klist_node(prev->n_node.prev);
+       }
+
+       spin_unlock(&i->i_klist->k_lock);
+
+       if (put && last)
+               put(last);
+       return i->i_cur;
+}
+EXPORT_SYMBOL_GPL(klist_prev);
+
 /**
  * klist_next - Ante up next node in list.
  * @i: Iterator structure.