Re: [PATCH 5/5] null_blk: Zero-initialize read buffers in non-memory-backed mode

On 2020/05/18 11:56, Bart Van Assche wrote:

On 2020-05-17 19:10, Damien Le Moal wrote:

quoted

On 2020/05/18 10:32, Bart Van Assche wrote:

quoted

On 2020-05-17 18:12, Damien Le Moal wrote:

quoted

On 2020/05/16 9:19, Bart Van Assche wrote:

quoted

+static void nullb_zero_rq_data_buffer(const struct request *rq)
+{
+	struct req_iterator iter;
+	struct bio_vec bvec;
+
+	rq_for_each_bvec(bvec, rq, iter)
+		zero_fill_bvec(&bvec);
+}
+
+static void nullb_zero_read_cmd_buffer(struct nullb_cmd *cmd)
+{
+	struct nullb_device *dev = cmd->nq->dev;
+
+	if (dev->queue_mode == NULL_Q_BIO && bio_op(cmd->bio) == REQ_OP_READ)
+		zero_fill_bio(cmd->bio);
+	else if (req_op(cmd->rq) == REQ_OP_READ)
+		nullb_zero_rq_data_buffer(cmd->rq);
+}

Shouldn't the definition of these two functions be under a "#ifdef CONFIG_KMSAN" ?

It is on purpose that I used IS_ENABLED(CONFIG_KMSAN) below instead of
#ifdef CONFIG_KMSAN. CONFIG_KMSAN is not yet upstream and I want to
expose the above code to the build robot.

But then you will get a "defined but unused" build warning, no ?

Not when using IS_ENABLED(...).

I do not understand: the "if (IS_ENABLED(CONFIG_KMSAN))" will be compiled out if
CONFIG_KMSAN is not enabled/defined, but the function definitions will still
remain, won't they ? That will lead to "defined but unused" warning, no ? What
am I missing here ?

Bart.

-- 
Damien Le Moal
Western Digital Research