[PATCH] virtio_console: free unused buffers with virtio port

From: Pankaj Gupta
Date: Mon Mar 04 2019 - 08:05:22 EST


The commit a7a69ec0d8e4 ("virtio_console: free buffers after reset")
deffered detaching of unused buffer to virtio device unplug time.

This causes unplug/replug of single port in virtio device with an
error "Error allocating inbufs\n". As we don't free the unused buffers
attached with the port. Re-plug the same port tries to allocate new
buffers in virtqueue and results in this error if queue is full.

This patch removes the unused buffers in vq's when we unplug the port.
This is the best we can do as we cannot call device_reset because virtio
device is still active. This was the working behaviour before the change
introduced in commit b3258ff1d6.

Reported-by: Xiaohui Li <xiaohli@xxxxxxxxxx>
Fixes: b3258ff1d6 ("virtio_console: free buffers after reset")
Signed-off-by: Pankaj Gupta <pagupta@xxxxxxxxxx>
---
drivers/char/virtio_console.c | 14 +++++++++++---
1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c
index fbeb71953526..5fbf2ac73111 100644
--- a/drivers/char/virtio_console.c
+++ b/drivers/char/virtio_console.c
@@ -1506,15 +1506,25 @@ static void remove_port(struct kref *kref)
kfree(port);
}

+static void remove_unused_bufs(struct virtqueue *vq)
+{
+ struct port_buffer *buf;
+
+ while ((buf = virtqueue_detach_unused_buf(vq)))
+ free_buf(buf, true);
+}
+
static void remove_port_data(struct port *port)
{
spin_lock_irq(&port->inbuf_lock);
/* Remove unused data this port might have received. */
discard_port_data(port);
+ remove_unused_bufs(port->in_vq);
spin_unlock_irq(&port->inbuf_lock);

spin_lock_irq(&port->outvq_lock);
reclaim_consumed_buffers(port);
+ remove_unused_bufs(port->out_vq);
spin_unlock_irq(&port->outvq_lock);
}

@@ -1950,11 +1960,9 @@ static void remove_vqs(struct ports_device *portdev)
struct virtqueue *vq;

virtio_device_for_each_vq(portdev->vdev, vq) {
- struct port_buffer *buf;

flush_bufs(vq, true);
- while ((buf = virtqueue_detach_unused_buf(vq)))
- free_buf(buf, true);
+ remove_unused_bufs(vq);
}
portdev->vdev->config->del_vqs(portdev->vdev);
kfree(portdev->in_vqs);
--
2.20.1