Re: [RFC v3 1/1] s390/cio: remove uevent suppress from cio driver

[Cornelia Huck <cohuck@redhat.com>]

On Mon, Nov 22 2021, Vineeth Vijayan <vneethv@linux.ibm.com> wrote:

> commit fa1a8c23eb7d ("s390: cio: Delay uevents for subchannels")
> introduced suppression of uevents for a subchannel until after it is
> clear that the subchannel would not be unregistered again
> immediately. This was done to avoid uevents being generated for I/O
> subchannels with no valid device, which can happen on LPAR.
>
> However, this also has some drawbacks: All subchannel drivers need to
> manually remove the uevent suppression and generate an ADD uevent as
> soon as they are sure that the subchannel will stay around. This misses
> out on all uevents that are not the initial ADD uevent that would be
> generated while uevents are suppressed; for example, all subchannels
> were missing the BIND uevent.
>
> As uevents being generated even for I/O subchannels without an
> operational device turned out to be not as bad as missing uevents and
> complicating the code flow, let's remove uevent suppression for
> subchannel

s/subchannel/subchannels./

>
> Signed-off-by: Vineeth Vijayan <vneethv@linux.ibm.com>
> [cohuck@redhat.com: modified changelog]
> ---
>  drivers/s390/cio/chsc_sch.c     |  5 -----
>  drivers/s390/cio/css.c          | 19 -------------------
>  drivers/s390/cio/device.c       | 18 ------------------
>  drivers/s390/cio/eadm_sch.c     |  5 -----
>  drivers/s390/cio/vfio_ccw_drv.c |  5 -----
>  5 files changed, 52 deletions(-)

(...)

> @@ -1035,16 +1027,6 @@ static int io_subchannel_probe(struct subchannel *sch)
>  				      "attributes for subchannel "
>  				      "0.%x.%04x (rc=%d)\n",
>  				      sch->schid.ssid, sch->schid.sch_no, rc);
> -		/*
> -		 * The console subchannel already has an associated ccw_device.
> -		 * Throw the delayed uevent for the subchannel, register
> -		 * the ccw_device and exit.

Maybe keep at least part of this comment?

/*
 * The console subchannel already has an associated ccw_device.
 * Register it and exit.
 */

> -		 */
> -		if (dev_get_uevent_suppress(&sch->dev)) {
> -			/* should always be the case for the console */
> -			dev_set_uevent_suppress(&sch->dev, 0);
> -			kobject_uevent(&sch->dev.kobj, KOBJ_ADD);
> -		}
>  		cdev = sch_get_cdev(sch);
>  		rc = device_add(&cdev->dev);
>  		if (rc) {

Otherwise looks good to me.

Reviewed-by: Cornelia Huck <cohuck@redhat.com>