The comment of interval_tree_span_iter_next_gap() is not exact, nodes[1] is not always !NULL. There are threes cases here. If there is an interior hole, the statement is correct. If there is a tailing hole or the contiguous used range span to the end, nodes[1] is NULL. Signed-off-by: Wei Yang <richard.weiyang@xxxxxxxxx> CC: Matthew Wilcox <willy@xxxxxxxxxxxxx> CC: Michel Lespinasse <michel@xxxxxxxxxxxxxx> CC: Jason Gunthorpe <jgg@xxxxxxxx> --- lib/interval_tree.c | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-) diff --git a/lib/interval_tree.c b/lib/interval_tree.c index 3412737ff365..87bcdd387d1a 100644 --- a/lib/interval_tree.c +++ b/lib/interval_tree.c @@ -20,9 +20,15 @@ EXPORT_SYMBOL_GPL(interval_tree_iter_next); /* * Roll nodes[1] into nodes[0] by advancing nodes[1] to the end of a contiguous * span of nodes. This makes nodes[0]->last the end of that contiguous used span - * indexes that started at the original nodes[1]->start. nodes[1] is now the - * first node starting the next used span. A hole span is between nodes[0]->last - * and nodes[1]->start. nodes[1] must be !NULL. + * indexes that started at the original nodes[1]->start. + * + * If there is an interior hole, nodes[1] is now the first node starting the + * next used span. A hole span is between nodes[0]->last and nodes[1]->start. + * + * If there is a tailing hole, nodes[1] is now NULL. A hole span is between + * nodes[0]->last and last_index. + * + * If the contiguous used range span to last_index, nodes[1] is set to NULL. */ static void interval_tree_span_iter_next_gap(struct interval_tree_span_iter *state) -- 2.34.1
