virtio_ccw: introduce device_lost in virtio_ccw_device

When a device is lost, the common I/O layer calls the notification
handler with CIO_GONE: In that event, flag device_lost as true.

In case the device had been flagged as lost when the remove/offline callbacks
are called, call the new virtio_break_device() function prior to invoking
device_unregister(). This avoids hangs of I/O triggered via the device
unregistration callbacks.

Signed-off-by: Heinz Graalfs <graalfs@linux.vnet.ibm.com>
Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

diff --git a/drivers/s390/kvm/virtio_ccw.c b/drivers/s390/kvm/virtio_ccw.c
index 1e1fc671f89a4a431b4a04f59fea16e302ad3a30..d2c0b442bce5fb010fc43414a266c34ee245ca54 100644 (file)
--- a/drivers/s390/kvm/virtio_ccw.c
+++ b/drivers/s390/kvm/virtio_ccw.c
@@ -27,6 +27,7 @@
 #include <linux/module.h>
 #include <linux/io.h>
 #include <linux/kvm_para.h>
+#include <linux/notifier.h>
 #include <asm/setup.h>
 #include <asm/irq.h>
 #include <asm/cio.h>
@@ -62,6 +63,7 @@ struct virtio_ccw_device {
        struct vq_config_block *config_block;
        bool is_thinint;
        bool going_away;
+       bool device_lost;
        void *airq_info;
 };
 
@@ -1010,11 +1012,14 @@ static void virtio_ccw_remove(struct ccw_device *cdev)
        unsigned long flags;
        struct virtio_ccw_device *vcdev = virtio_grab_drvdata(cdev);
 
-       if (vcdev && cdev->online)
+       if (vcdev && cdev->online) {
+               if (vcdev->device_lost)
+                       virtio_break_device(&vcdev->vdev);
                unregister_virtio_device(&vcdev->vdev);
-       spin_lock_irqsave(get_ccwdev_lock(cdev), flags);
-       dev_set_drvdata(&cdev->dev, NULL);
-       spin_unlock_irqrestore(get_ccwdev_lock(cdev), flags);
+               spin_lock_irqsave(get_ccwdev_lock(cdev), flags);
+               dev_set_drvdata(&cdev->dev, NULL);
+               spin_unlock_irqrestore(get_ccwdev_lock(cdev), flags);
+       }
        cdev->handler = NULL;
 }
 
@@ -1023,12 +1028,14 @@ static int virtio_ccw_offline(struct ccw_device *cdev)
        unsigned long flags;
        struct virtio_ccw_device *vcdev = virtio_grab_drvdata(cdev);
 
-       if (vcdev) {
-               unregister_virtio_device(&vcdev->vdev);
-               spin_lock_irqsave(get_ccwdev_lock(cdev), flags);
-               dev_set_drvdata(&cdev->dev, NULL);
-               spin_unlock_irqrestore(get_ccwdev_lock(cdev), flags);
-       }
+       if (!vcdev)
+               return 0;
+       if (vcdev->device_lost)
+               virtio_break_device(&vcdev->vdev);
+       unregister_virtio_device(&vcdev->vdev);
+       spin_lock_irqsave(get_ccwdev_lock(cdev), flags);
+       dev_set_drvdata(&cdev->dev, NULL);
+       spin_unlock_irqrestore(get_ccwdev_lock(cdev), flags);
        return 0;
 }
 
@@ -1096,8 +1103,26 @@ out_free:
 
 static int virtio_ccw_cio_notify(struct ccw_device *cdev, int event)
 {
-       /* TODO: Check whether we need special handling here. */
-       return 0;
+       int rc;
+       struct virtio_ccw_device *vcdev = dev_get_drvdata(&cdev->dev);
+
+       /*
+        * Make sure vcdev is set
+        * i.e. set_offline/remove callback not already running
+        */
+       if (!vcdev)
+               return NOTIFY_DONE;
+
+       switch (event) {
+       case CIO_GONE:
+               vcdev->device_lost = true;
+               rc = NOTIFY_DONE;
+               break;
+       default:
+               rc = NOTIFY_DONE;
+               break;
+       }
+       return rc;
 }
 
 static struct ccw_device_id virtio_ids[] = {