On 04/22/2017 01:40 AM, Bart Van Assche wrote:
> This new callback function will be used in the next patch to show
> more information about SCSI requests.
>
> Signed-off-by: Bart Van Assche <bart.vanassche@xxxxxxxxxxx>
> Reviewed-by: Omar Sandoval <osandov@xxxxxx>
> Cc: Hannes Reinecke <hare@xxxxxxxx>
> ---
> block/blk-mq-debugfs.c | 6 +++++-
> include/linux/blk-mq.h | 6 ++++++
> 2 files changed, 11 insertions(+), 1 deletion(-)
>
> diff --git a/block/blk-mq-debugfs.c b/block/blk-mq-debugfs.c
> index 3a99146ece39..c5eca9245459 100644
> --- a/block/blk-mq-debugfs.c
> +++ b/block/blk-mq-debugfs.c
> @@ -311,6 +311,7 @@ static const char *const rqf_name[] = {
> static int blk_mq_debugfs_rq_show(struct seq_file *m, void *v)
> {
> struct request *rq = list_entry_rq(v);
> + const struct blk_mq_ops *const mq_ops = rq->q->mq_ops;
> const unsigned int op = rq->cmd_flags & REQ_OP_MASK;
>
> seq_printf(m, "%p {.op=", rq);
> @@ -324,8 +325,11 @@ static int blk_mq_debugfs_rq_show(struct seq_file *m, void *v)
> seq_puts(m, ", .rq_flags=");
> blk_flags_show(m, (__force unsigned int)rq->rq_flags, rqf_name,
> ARRAY_SIZE(rqf_name));
> - seq_printf(m, ", .tag=%d, .internal_tag=%d}\n", rq->tag,
> + seq_printf(m, ", .tag=%d, .internal_tag=%d", rq->tag,
> rq->internal_tag);
> + if (mq_ops->show_rq)
> + mq_ops->show_rq(m, rq);
> + seq_puts(m, "}\n");
> return 0;
> }
>
> diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h
> index 0c4dadb85f62..b7bf11c05568 100644
> --- a/include/linux/blk-mq.h
> +++ b/include/linux/blk-mq.h
> @@ -121,6 +121,12 @@ struct blk_mq_ops {
> softirq_done_fn *complete;
>
> /*
> + * Used by the debugfs implementation to show driver-specific
> + * information about a request.
> + */
> + void (*show_rq)(struct seq_file *m, struct request *rq);
> +
> + /*
> * Called when the block layer side of a hardware queue has been
> * set up, allowing the driver to allocate/init matching structures.
> * Ditto for exit/teardown.
>
I don't really like this; what does happen if someone disabled
CONFIG_BLK_DEBUGFS?
Won't we end up with a stale callback?
Cheers,
Hannes
--
Dr. Hannes Reinecke zSeries & Storage
hare@xxxxxxxx +49 911 74053 688
SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: F. Imendörffer, J. Smithard, D. Upmanyu, G. Norton
HRB 21284 (AG Nürnberg)
