On Thu, Dec 06, 2018 at 08:06:16AM -0800, Bart Van Assche wrote: > On Wed, 2018-12-05 at 22:59 +0800, Weiping Zhang wrote: > > Weiping Zhang <zwp10758@xxxxxxxxx> 于2018年12月5日周三 下午10:49写道： > > > Christoph Hellwig <hch@xxxxxxxxxxxxx> 于2018年12月5日周三 下午10:40写道： > > > > Can you please also send a patch to not show this attribute for > > > > drivers without a timeout handler? Thanks! > > > > Is there a simple way do that ? > > How about checking the timeout member of struct blk_mq_ops for blk-mq and > checking the rq_timed_out_fn member in struct request_queue for the legacy > block layer? Just the former given that the legacy code is gone in for-next. > > Shall we return -ENOTSUPP when user read/write this attribute when > > driver has no timeout handler ? > > A much more elegant solution is to introduce a sysfs attribute group for the > io_timeout attribute and to make that group visible only if a timeout handler > has been defined. See e.g. disk_attr_group in block/genhd.c for an example. Agreed, that is the way to go.
