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Commit ee7fb5b3 authored by Michael S. Tsirkin's avatar Michael S. Tsirkin Committed by Sasha Levin
Browse files

virtio_console: avoid config access from irq 



[ Upstream commit eeb8a7e8bb123e84daeef84f5a2eab99ad2839a2 ]

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: default avatarMichael S. Tsirkin <mst@redhat.com>
Reviewed-by: default avatarAmit Shah <amit.shah@redhat.com>
Signed-off-by: default avatarRusty Russell <rusty@rustcorp.com.au>
Cc: stable@kernel.org
Signed-off-by: default avatarSasha Levin <sasha.levin@oracle.com>
parent 0b39fb19

drivers/char/virtio_console.c

+16 −0
Original line number Diff line number Diff line
@@ -142,6 +142,7 @@ struct ports_device { 
	 * notification

	 */

	struct work_struct control_work;

	struct work_struct config_work;



	struct list_head ports;
@@ -1832,10 +1833,21 @@ static void config_intr(struct virtio_device *vdev) 


	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);
@@ -2026,6 +2038,7 @@ static int virtcons_probe(struct virtio_device *vdev) 


	virtio_device_ready(portdev->vdev);



	INIT_WORK(&portdev->config_work, &config_work_handler);

	INIT_WORK(&portdev->control_work, &control_work_handler);



	if (multiport) {
@@ -2100,6 +2113,8 @@ static void virtcons_remove(struct virtio_device *vdev) 
	/* 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);
@@ -2151,6 +2166,7 @@ static int virtcons_freeze(struct virtio_device *vdev) 


	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.