On 27.03.2020 13:45, Cornelia Huck wrote:
> The common I/O layer delays the ADD uevent for subchannels and
> delegates generating this uevent to the individual subchannel
> drivers. The io_subchannel driver will do so when the associated
> ccw_device has been registered -- but unconditionally, so more
> ADD uevents will be generated if a subchannel has been unbound
> from the io_subchannel driver and later rebound.
>
> To fix this, only generate the ADD event if uevents were still
> suppressed for the device.
>
> Reported-by: Boris Fiuczynski <fiuczy@xxxxxxxxxxxxx>
> Fixes: fa1a8c23eb7d ("s390: cio: Delay uevents for subchannels")
> Signed-off-by: Cornelia Huck <cohuck@xxxxxxxxxx>
Please also add Vineeth on cc of future patches against core CIO code.
This patch looks sane and makes handling of suppressed UDEV events
consistent to what is already implemented for CHSC and EADM subchannel
types.
Reviewed-by: Peter Oberparleiter <oberpar@xxxxxxxxxxxxx>
> ---
> drivers/s390/cio/device.c | 13 +++++++++----
> 1 file changed, 9 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/s390/cio/device.c b/drivers/s390/cio/device.c
> index 0c6245fc7706..983f9c9e08de 100644
> --- a/drivers/s390/cio/device.c
> +++ b/drivers/s390/cio/device.c
> @@ -849,8 +849,10 @@ static void io_subchannel_register(struct ccw_device *cdev)
> * Now we know this subchannel will stay, we can throw
> * our delayed uevent.
> */
> - dev_set_uevent_suppress(&sch->dev, 0);
> - kobject_uevent(&sch->dev.kobj, KOBJ_ADD);
> + if (dev_get_uevent_suppress(&sch->dev)) {
> + dev_set_uevent_suppress(&sch->dev, 0);
> + kobject_uevent(&sch->dev.kobj, KOBJ_ADD);
> + }
> /* make it known to the system */
> ret = ccw_device_add(cdev);
> if (ret) {
> @@ -1058,8 +1060,11 @@ static int io_subchannel_probe(struct subchannel *sch)
> * Throw the delayed uevent for the subchannel, register
> * the ccw_device and exit.
> */
> - dev_set_uevent_suppress(&sch->dev, 0);
> - kobject_uevent(&sch->dev.kobj, KOBJ_ADD);
> + 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 = ccw_device_add(cdev);
> if (rc) {
>
--
Peter Oberparleiter
Linux on Z Development - IBM Germany
