blktrace: annotate required lock on do_blk_trace_setup()

Ensure it is clear which lock is required on do_blk_trace_setup().

Suggested-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/kernel/trace/blktrace.c b/kernel/trace/blktrace.c
index 5ef0484..5a88a6b 100644 (file)
--- a/kernel/trace/blktrace.c
+++ b/kernel/trace/blktrace.c
@@ -483,6 +483,8 @@ static int do_blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
        struct dentry *dir = NULL;
        int ret;
 
+       lockdep_assert_held(&q->blk_trace_mutex);
+
        if (!buts->buf_size || !buts->buf_nr)
                return -EINVAL;