s390/cio: remove uevent suppress from cio driver

commit fa1a8c23 ("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
subchannels.
Signed-off-by: Vineeth Vijayan <vneethv@linux.ibm.com>
[cohuck@redhat.com: modified changelog]
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Reviewed-by: Peter Oberparleiter <oberpar@linux.ibm.com>
Link: https://lore.kernel.org/r/20211122103756.352463-2-vneethv@linux.ibm.comSigned-off-by: Heiko Carstens <hca@linux.ibm.com>

drivers/s390/cio/chsc_sch.c

@@ -91,11 +91,6 @@ static int chsc_subchannel_probe(struct subchannel *sch)
 			 sch->schid.ssid, sch->schid.sch_no, ret);
 		dev_set_drvdata(&sch->dev, NULL);
 		kfree(private);
-	} else {
-		if (dev_get_uevent_suppress(&sch->dev)) {
-			dev_set_uevent_suppress(&sch->dev, 0);
-			kobject_uevent(&sch->dev.kobj, KOBJ_ADD);
-		}
 	}
 	return ret;
 }

drivers/s390/cio/css.c

@@ -470,16 +470,6 @@ int css_register_subchannel(struct subchannel *sch)
 	if (sch->st == SUBCHANNEL_TYPE_IO)
 		sch->dev.type = &io_subchannel_type;
 
-	/*
-	 * We don't want to generate uevents for I/O subchannels that don't
-	 * have a working ccw device behind them since they will be
-	 * unregistered before they can be used anyway, so we delay the add
-	 * uevent until after device recognition was successful.
-	 * Note that we suppress the uevent for all subchannel types;
-	 * the subchannel driver can decide itself when it wants to inform
-	 * userspace of its existence.
-	 */
-	dev_set_uevent_suppress(&sch->dev, 1);
 	css_update_ssd_info(sch);
 	/* make it known to the system */
 	ret = css_sch_device_register(sch);
@@ -488,15 +478,6 @@ int css_register_subchannel(struct subchannel *sch)
 			      sch->schid.ssid, sch->schid.sch_no, ret);
 		return ret;
 	}
-	if (!sch->driver) {
-		/*
-		 * No driver matched. Generate the uevent now so that
-		 * a fitting driver module may be loaded based on the
-		 * modalias.
-		 */
-		dev_set_uevent_suppress(&sch->dev, 0);
-		kobject_uevent(&sch->dev.kobj, KOBJ_ADD);
-	}
 	return ret;
 }
 

drivers/s390/cio/device.c

@@ -838,14 +838,6 @@ static void io_subchannel_register(struct ccw_device *cdev)
 		adjust_init_count = 0;
 		goto out;
 	}
-	/*
-	 * Now we know this subchannel will stay, we can throw
-	 * our delayed uevent.
-	 */
-	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 = device_add(&cdev->dev);
 	if (ret) {
@@ -1036,15 +1028,9 @@ static int io_subchannel_probe(struct subchannel *sch)
 				      "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.
-		 */
-		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);
-		}
+		* The console subchannel already has an associated ccw_device.
+		* Register it and exit.
+		*/
 		cdev = sch_get_cdev(sch);
 		rc = device_add(&cdev->dev);
 		if (rc) {

drivers/s390/cio/eadm_sch.c

@@ -243,11 +243,6 @@ static int eadm_subchannel_probe(struct subchannel *sch)
 	spin_lock_irq(&list_lock);
 	list_add(&private->head, &eadm_list);
 	spin_unlock_irq(&list_lock);
-
-	if (dev_get_uevent_suppress(&sch->dev)) {
-		dev_set_uevent_suppress(&sch->dev, 0);
-		kobject_uevent(&sch->dev.kobj, KOBJ_ADD);
-	}
 out:
 	return ret;
 }

drivers/s390/cio/vfio_ccw_drv.c

@@ -244,11 +244,6 @@ static int vfio_ccw_sch_probe(struct subchannel *sch)
 	if (ret)
 		goto out_disable;
 
-	if (dev_get_uevent_suppress(&sch->dev)) {
-		dev_set_uevent_suppress(&sch->dev, 0);
-		kobject_uevent(&sch->dev.kobj, KOBJ_ADD);
-	}
-
 	VFIO_CCW_MSG_EVENT(4, "bound to subchannel %x.%x.%04x\n",
 			   sch->schid.cssid, sch->schid.ssid,
 			   sch->schid.sch_no);