latch_tree_find() should be protected by caller via RCU or so.
When it find a node in an attempt, the node must be a valid one
in RCU's point's of view even the tree is (being) updated with a
new node with the same key which is entirely subject to timing
anyway.
Cc: Paul E. McKenney <paul...@kernel.org>
Cc: Oleg Nesterov <o...@redhat.com>
Cc: Michel Lespinasse <wal...@google.com>
Cc: Andrea Arcangeli <aarca...@redhat.com>
Cc: Rik van Riel <r...@redhat.com>
Cc: Mathieu Desnoyers <mathieu.desnoy...@efficios.com>
Acked-by: Peter Zijlstra (Intel) <pet...@infradead.org>
Signed-off-by: Lai Jiangshan <la...@linux.alibaba.com>
---
include/linux/rbtree_latch.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/include/linux/rbtree_latch.h b/include/linux/rbtree_latch.h
index 638942f53c0a..affc4b026d9b 100644
--- a/include/linux/rbtree_latch.h
+++ b/include/linux/rbtree_latch.h
@@ -245,7 +245,7 @@ latch_tree_find(void *key, struct latch_tree_root *root,
do {
seq = raw_read_seqcount_latch(&root->seq);
node = __lt_find(key, root, seq & 1, ops->comp);
- } while (read_seqcount_retry(&root->seq, seq));
+ } while (!node && read_seqcount_retry(&root->seq, seq));
return node;
}
--
2.20.1
