From a26142559c2be8c0975b941e3110d23a9e552ce5 Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Fri, 6 Sep 2019 07:02:31 -0600 Subject: [PATCH] block: fix elevator_get_by_features() The lookup logic is broken - 'e' will never be NULL, even if the list is empty. Maintain lookup hit in a separate variable instead. Fixes: a0958ba7fcdc ("block: Improve default elevator selection") Reported-by: Julia Lawall Signed-off-by: Jens Axboe --- block/elevator.c | 13 +++++++------ 1 file changed, 7 insertions(+), 6 deletions(-) diff --git a/block/elevator.c b/block/elevator.c index 096a670d22d7..bba10e83478a 100644 --- a/block/elevator.c +++ b/block/elevator.c @@ -668,22 +668,23 @@ static struct elevator_type *elevator_get_default(struct request_queue *q) */ static struct elevator_type *elevator_get_by_features(struct request_queue *q) { - struct elevator_type *e; + struct elevator_type *e, *found = NULL; spin_lock(&elv_list_lock); list_for_each_entry(e, &elv_list, list) { if (elv_support_features(e->elevator_features, - q->required_elevator_features)) + q->required_elevator_features)) { + found = e; break; + } } - if (e && !try_module_get(e->elevator_owner)) - e = NULL; + if (found && !try_module_get(found->elevator_owner)) + found = NULL; spin_unlock(&elv_list_lock); - - return e; + return found; } /* -- 2.30.2