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| author | Jun'ichi Nomura <j-nomura@ce.jp.nec.com> | 2012-10-22 10:15:37 +0900 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2012-10-22 22:00:26 +0200 |
| commit | 65c77fd9e8a1c8c3da0bbbea6b7efa3d6ef265f8 (patch) | |
| tree | 305b08304869b3f8d57a191b4b23968e53b53247 /block | |
| parent | 65635cbc37e011e71b208257a25e7c1078cd039b (diff) | |
| download | lwn-65c77fd9e8a1c8c3da0bbbea6b7efa3d6ef265f8.tar.gz lwn-65c77fd9e8a1c8c3da0bbbea6b7efa3d6ef265f8.zip | |
blkcg: stop iteration early if root_rl is the only request list
__blk_queue_next_rl() finds next request list based on blkg_list
while skipping root_blkg in the list.
OTOH, root_rl is special as it may exist even without root_blkg.
Though the later part of the function handles such a case correctly,
exiting early is good for readability of the code.
Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com>
Cc: Tejun Heo <tj@kernel.org>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'block')
| -rw-r--r-- | block/blk-cgroup.c | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c index 3ad5e3fbf579..d0b770391ad4 100644 --- a/block/blk-cgroup.c +++ b/block/blk-cgroup.c @@ -333,6 +333,9 @@ struct request_list *__blk_queue_next_rl(struct request_list *rl, */ if (rl == &q->root_rl) { ent = &q->blkg_list; + /* There are no more block groups, hence no request lists */ + if (list_empty(ent)) + return NULL; } else { blkg = container_of(rl, struct blkcg_gq, rl); ent = &blkg->q_node; |