From: Liu Bo <bo.liu@xxxxxxxxxxxxxxxxx> commit e1a413245a564683697a3d02ec197b72cf009b89 upstream. Since @blk_debugfs_root couldn't be configured dynamically, we can save a few memory allocation if it's not there. Signed-off-by: Liu Bo <bo.liu@xxxxxxxxxxxxxxxxx> Signed-off-by: Jens Axboe <axboe@xxxxxxxxx> [bwh: Cherry-picked for 4.14 to ease backporting a later fix] Signed-off-by: Ben Hutchings <ben.hutchings@xxxxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- kernel/trace/blktrace.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) --- a/kernel/trace/blktrace.c +++ b/kernel/trace/blktrace.c @@ -498,6 +498,9 @@ static int do_blk_trace_setup(struct req if (!buts->buf_size || !buts->buf_nr) return -EINVAL; + if (!blk_debugfs_root) + return -ENOENT; + strncpy(buts->name, name, BLKTRACE_BDEV_SIZE); buts->name[BLKTRACE_BDEV_SIZE - 1] = '\0'; @@ -532,9 +535,6 @@ static int do_blk_trace_setup(struct req ret = -ENOENT; - if (!blk_debugfs_root) - goto err; - dir = debugfs_lookup(buts->name, blk_debugfs_root); if (!dir) bt->dir = dir = debugfs_create_dir(buts->name, blk_debugfs_root);
