| From | Greg Kroah-Hartman <> | Subject | [PATCH 3.19 044/123] virtio_console: avoid config access from irq | Date | Tue, 24 Mar 2015 16:45:53 +0100 |
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3.19-stable review patch. If anyone has any objections, please let me know.
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From: "Michael S. Tsirkin" <mst@redhat.com>
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@redhat.com> Reviewed-by: Amit Shah <amit.shah@redhat.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
--- 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.
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