s390: cio: Delay uevents for subchannels

We often have the situation that we register a subchannel and start device
recognition, only to find out that the device is not usable after all, which
triggers an unregister of the subchannel.  This often happens on hundreds of
subchannels on a LPAR, leading to a storm of events which aren't of any use.
Therefore, use uevent_suppress to delay the KOBJ_ADD uevent for a subchannel
until we know that its ccw_device is to be registered.

Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Cc: Eric Rannaud <eric.rannaud@gmail.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/s390/cio/device.c b/drivers/s390/cio/device.c
index 03355902c582d0e465a3902dc60ecaaeb4c624ec..a23ff582db9ddf03b303aa6647d2d353f7e96294 100644 (file)
--- a/drivers/s390/cio/device.c
+++ b/drivers/s390/cio/device.c
@@ -871,6 +871,12 @@ io_subchannel_register(struct work_struct *work)
                }
                goto out;
        }
+       /*
+        * Now we know this subchannel will stay, we can throw
+        * our delayed uevent.
+        */
+       sch->dev.uevent_suppress = 0;
+       kobject_uevent(&sch->dev.kobj, KOBJ_ADD);
        /* make it known to the system */
        ret = ccw_device_register(cdev);
        if (ret) {