Previously, if LIST_HEAD_FORMAT was not set, `list -r` will traverse the
list in order, that doesn't obey the -r(reverse) semantics.

Per the code, -r(LIST_HEAD_REVERSE) only work with LIST_HEAD_FORMAT and
'-r' usage also says that "For a list linked with list_head structures",
so it's reasonable to enable LIST_HEAD_FORMAT for it.

Cc: Lianbo Jiang <lijiang@redhat.com>
Cc: Tao Liu <ltao@redhat.com>
Signed-off-by: Li Zhijian <lizhijian@fujitsu.com>

---
V2: enable LIST_HEAD_FORMAT for -r option instead of fatal when -h/-H is
not specified for -r. # Lianbo
---
 tools.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/tools.c b/tools.c
index 0f2db108838a..1022d579071a 100644
--- a/tools.c
+++ b/tools.c
@@ -3370,6 +3370,7 @@ cmd_list(void)
                        break;

                case 'r':
+                       ld->flags |= LIST_HEAD_FORMAT;
                        ld->flags |= LIST_HEAD_REVERSE;
                        break;

--
2.29.2