virtio_console: avoid config access from irq
when multiport is off, virtio console invokes config access from irq
context, config access is blocking on s390.
Fix this up by scheduling work from config irq - similar to what we do
for multiport configs.
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: stable@kernel.org
diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c
index def736d..72d7028 100644
--- a/drivers/char/virtio_console.c
+++ b/drivers/char/virtio_console.c
@@ -142,6 +142,7 @@
* notification
*/
struct work_struct control_work;
+ struct work_struct config_work;
struct list_head ports;
@@ -1837,10 +1838,21 @@
portdev = vdev->priv;
+ if (!use_multiport(portdev))
+ schedule_work(&portdev->config_work);
+}
+
+static void config_work_handler(struct work_struct *work)
+{
+ struct ports_device *portdev;
+
+ portdev = container_of(work, struct ports_device, control_work);
if (!use_multiport(portdev)) {
+ struct virtio_device *vdev;
struct port *port;
u16 rows, cols;
+ vdev = portdev->vdev;
virtio_cread(vdev, struct virtio_console_config, cols, &cols);
virtio_cread(vdev, struct virtio_console_config, rows, &rows);
@@ -2040,6 +2052,7 @@
virtio_device_ready(portdev->vdev);
+ INIT_WORK(&portdev->config_work, &config_work_handler);
INIT_WORK(&portdev->control_work, &control_work_handler);
if (multiport) {
@@ -2114,6 +2127,8 @@
/* Finish up work that's lined up */
if (use_multiport(portdev))
cancel_work_sync(&portdev->control_work);
+ else
+ cancel_work_sync(&portdev->config_work);
list_for_each_entry_safe(port, port2, &portdev->ports, list)
unplug_port(port);
@@ -2165,6 +2180,7 @@
virtqueue_disable_cb(portdev->c_ivq);
cancel_work_sync(&portdev->control_work);
+ cancel_work_sync(&portdev->config_work);
/*
* Once more: if control_work_handler() was running, it would
* enable the cb as the last step.