Re: [PATCH v4 09/10] blk-mq: Add blk_mq_ops.show_rq()

Bart Van Assche
2017-04-24T21:51:46Z

On Mon, 2017-04-24 at 09:32 +0200, Hannes Reinecke wrote:
> On 04/22/2017 01:40 AM, Bart Van Assche wrote:
> > --- a/include/linux/blk-mq.h
> > +++ b/include/linux/blk-mq.h
> > @@ -121,6 +121,12 @@ struct blk_mq_ops {
> > softirq_done_fn *complete;
> > =20
> > /*
> > + * 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.
> >=20
>=20
> I don't really like this; what does happen if someone disabled
> CONFIG_BLK_DEBUGFS? Won't we end up with a stale callback?

Hello Hannes,

How about surrounding (*show_rq)() function pointer with #ifdef CONFIG_BLK_=
DEBUGFS /
#endif?

Bart.=