From: Laurent Vivier lvivier@redhat.com
commit d791cfcbf98191122af70b053a21075cb450d119 upstream.
When we hot unplug a virtserialport and then try to hot plug again, it fails:
(qemu) chardev-add socket,id=serial0,path=/tmp/serial0,server,nowait (qemu) device_add virtserialport,bus=virtio-serial0.0,nr=2,\ chardev=serial0,id=serial0,name=serial0 (qemu) device_del serial0 (qemu) device_add virtserialport,bus=virtio-serial0.0,nr=2,\ chardev=serial0,id=serial0,name=serial0 kernel error: virtio-ports vport2p2: Error allocating inbufs qemu error: virtio-serial-bus: Guest failure in adding port 2 for device \ virtio-serial0.0
This happens because buffers for the in_vq are allocated when the port is added but are not released when the port is unplugged.
They are only released when virtconsole is removed (see a7a69ec0d8e4)
To avoid the problem and to be symmetric, we could allocate all the buffers in init_vqs() as they are released in remove_vqs(), but it sounds like a waste of memory.
Rather than that, this patch changes add_port() logic to ignore ENOSPC error in fill_queue(), which means queue has already been filled.
Fixes: a7a69ec0d8e4 ("virtio_console: free buffers after reset") Cc: mst@redhat.com Cc: stable@vger.kernel.org Signed-off-by: Laurent Vivier lvivier@redhat.com Signed-off-by: Michael S. Tsirkin mst@redhat.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/char/virtio_console.c | 28 +++++++++++++--------------- 1 file changed, 13 insertions(+), 15 deletions(-)
--- a/drivers/char/virtio_console.c +++ b/drivers/char/virtio_console.c @@ -1366,24 +1366,24 @@ static void set_console_size(struct port port->cons.ws.ws_col = cols; }
-static unsigned int fill_queue(struct virtqueue *vq, spinlock_t *lock) +static int fill_queue(struct virtqueue *vq, spinlock_t *lock) { struct port_buffer *buf; - unsigned int nr_added_bufs; + int nr_added_bufs; int ret;
nr_added_bufs = 0; do { buf = alloc_buf(vq->vdev, PAGE_SIZE, 0); if (!buf) - break; + return -ENOMEM;
spin_lock_irq(lock); ret = add_inbuf(vq, buf); if (ret < 0) { spin_unlock_irq(lock); free_buf(buf, true); - break; + return ret; } nr_added_bufs++; spin_unlock_irq(lock); @@ -1403,7 +1403,6 @@ static int add_port(struct ports_device char debugfs_name[16]; struct port *port; dev_t devt; - unsigned int nr_added_bufs; int err;
port = kmalloc(sizeof(*port), GFP_KERNEL); @@ -1462,11 +1461,13 @@ static int add_port(struct ports_device spin_lock_init(&port->outvq_lock); init_waitqueue_head(&port->waitqueue);
- /* Fill the in_vq with buffers so the host can send us data. */ - nr_added_bufs = fill_queue(port->in_vq, &port->inbuf_lock); - if (!nr_added_bufs) { + /* We can safely ignore ENOSPC because it means + * the queue already has buffers. Buffers are removed + * only by virtcons_remove(), not by unplug_port() + */ + err = fill_queue(port->in_vq, &port->inbuf_lock); + if (err < 0 && err != -ENOSPC) { dev_err(port->dev, "Error allocating inbufs\n"); - err = -ENOMEM; goto free_device; }
@@ -2099,14 +2100,11 @@ static int virtcons_probe(struct virtio_ INIT_WORK(&portdev->control_work, &control_work_handler);
if (multiport) { - unsigned int nr_added_bufs; - spin_lock_init(&portdev->c_ivq_lock); spin_lock_init(&portdev->c_ovq_lock);
- nr_added_bufs = fill_queue(portdev->c_ivq, - &portdev->c_ivq_lock); - if (!nr_added_bufs) { + err = fill_queue(portdev->c_ivq, &portdev->c_ivq_lock); + if (err < 0) { dev_err(&vdev->dev, "Error allocating buffers for control queue\n"); /* @@ -2117,7 +2115,7 @@ static int virtcons_probe(struct virtio_ VIRTIO_CONSOLE_DEVICE_READY, 0); /* Device was functional: we need full cleanup. */ virtcons_remove(vdev); - return -ENOMEM; + return err; } } else { /*