This is a note to let you know that I've just added the patch titled
virtio_console: avoid config access from irq
to the 3.19-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
virtio_console-avoid-config-access-from-irq.patch
and it can be found in the queue-3.19 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From eeb8a7e8bb123e84daeef84f5a2eab99ad2839a2 Mon Sep 17 00:00:00 2001
From: "Michael S. Tsirkin" <mst@xxxxxxxxxx>
Date: Thu, 5 Mar 2015 10:45:49 +1030
Subject: virtio_console: avoid config access from irq
From: "Michael S. Tsirkin" <mst@xxxxxxxxxx>
commit eeb8a7e8bb123e84daeef84f5a2eab99ad2839a2 upstream.
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@xxxxxxxxxx>
Reviewed-by: Amit Shah <amit.shah@xxxxxxxxxx>
Signed-off-by: Rusty Russell <rusty@xxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/char/virtio_console.c | 16 ++++++++++++++++
1 file changed, 16 insertions(+)
--- a/drivers/char/virtio_console.c
+++ b/drivers/char/virtio_console.c
@@ -142,6 +142,7 @@ struct ports_device {
* notification
*/
struct work_struct control_work;
+ struct work_struct config_work;
struct list_head ports;
@@ -1837,10 +1838,21 @@ static void config_intr(struct virtio_de
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);
@@ -2031,6 +2043,7 @@ static int virtcons_probe(struct virtio_
virtio_device_ready(portdev->vdev);
+ INIT_WORK(&portdev->config_work, &config_work_handler);
INIT_WORK(&portdev->control_work, &control_work_handler);
if (multiport) {
@@ -2105,6 +2118,8 @@ static void virtcons_remove(struct virti
/* 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);
@@ -2156,6 +2171,7 @@ static int virtcons_freeze(struct virtio
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.
Patches currently in stable-queue which might be from mst@xxxxxxxxxx are
queue-3.19/virtio-net-correctly-delete-napi-hash.patch
queue-3.19/virtio_console-init-work-unconditionally.patch
queue-3.19/virtio_console-avoid-config-access-from-irq.patch
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