[S390] cio: Only register ccw_device for registered subchannel.
There is a race between io_subchannel_register() and
io_subchannel_sch_event() which may cause a subchannel to be
unregistered because it is no longer operational before
io_subchannel_register() had run. We need to check whether the
subchannel is still registered before the ccw device can be
registered and just bail out if it is not.
Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
diff --git a/drivers/s390/cio/device.c b/drivers/s390/cio/device.c
index cba33aa..91acea1 100644
--- a/drivers/s390/cio/device.c
+++ b/drivers/s390/cio/device.c
@@ -950,6 +950,14 @@
priv = container_of(work, struct ccw_device_private, kick_work);
cdev = priv->cdev;
sch = to_subchannel(cdev->dev.parent);
+ /*
+ * Check if subchannel is still registered. It may have become
+ * unregistered if a machine check hit us after finishing
+ * device recognition but before the register work could be
+ * queued.
+ */
+ if (!device_is_registered(&sch->dev))
+ goto out_err;
css_update_ssd_info(sch);
/*
* io_subchannel_register() will also be called after device
@@ -984,18 +992,16 @@
spin_lock_irqsave(sch->lock, flags);
sch_set_cdev(sch, NULL);
spin_unlock_irqrestore(sch->lock, flags);
- /* Release reference for workqueue processing. */
- put_device(&cdev->dev);
/* Release initial device reference. */
put_device(&cdev->dev);
- if (atomic_dec_and_test(&ccw_device_init_count))
- wake_up(&ccw_device_init_wq);
- return;
+ goto out_err;
}
- put_device(&cdev->dev);
out:
cdev->private->flags.recog_done = 1;
wake_up(&cdev->private->wait_q);
+out_err:
+ /* Release reference for workqueue processing. */
+ put_device(&cdev->dev);
if (atomic_dec_and_test(&ccw_device_init_count))
wake_up(&ccw_device_init_wq);
}