We currently allow multiple instances of the control work handler to run
in parallel. This isn't expected to work; serialise access by disabling
interrupts on new packets from the Host and enable them when all the
existing ones are consumed.
Testcase: hot-plug/unplug a port in a loop. Without this patch, some
sysfs warnings are seen along with freezes. With the patch, all works
fine.
Reported-by: Miche Baker-Harvey <miche@xxxxxxxxxx>
Signed-off-by: Amit Shah <amit.shah@xxxxxxxxxx>
---
drivers/char/virtio_console.c | 6 ++++++
1 files changed, 6 insertions(+), 0 deletions(-)
diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c
index fd2fd6f..fc54a79 100644
--- a/drivers/char/virtio_console.c
+++ b/drivers/char/virtio_console.c
@@ -1471,6 +1471,7 @@ static void control_work_handler(struct work_struct *work)
portdev = container_of(work, struct ports_device, control_work);
vq = portdev->c_ivq;
+ start:
spin_lock(&portdev->cvq_lock);
while ((buf = virtqueue_get_buf(vq, &len))) {
spin_unlock(&portdev->cvq_lock);
@@ -1488,6 +1489,10 @@ static void control_work_handler(struct work_struct *work)
}
}
spin_unlock(&portdev->cvq_lock);
+ if (unlikely(!virtqueue_enable_cb(vq))) {
+ virtqueue_disable_cb(vq);
+ goto start;
+ }
}
static void out_intr(struct virtqueue *vq)
@@ -1538,6 +1543,7 @@ static void control_intr(struct virtqueue *vq)
{
struct ports_device *portdev;
+ virtqueue_disable_cb(vq);
portdev = vq->vdev->priv;
schedule_work(&portdev->control_work);
}
--
1.7.7.4
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