Message ID | 20231010062216.16144-1-loyou85@gmail.com |
---|---|
State | New |
Headers | show |
Series | virtio-serial-bus: Discard throttled VirtQueueElement when virtio-serial closed | expand |
diff --git a/hw/char/virtio-serial-bus.c b/hw/char/virtio-serial-bus.c index dd619f0..30b00a4 100644 --- a/hw/char/virtio-serial-bus.c +++ b/hw/char/virtio-serial-bus.c @@ -151,7 +151,7 @@ static void discard_vq_data(VirtQueue *vq, VirtIODevice *vdev) static void discard_throttle_data(VirtIOSerialPort *port) { if (port->elem) { - virtqueue_detach_element(port->ovq, port->elem, 0); + virtqueue_push(port->ovq, port->elem, 0); g_free(port->elem); port->elem = NULL; }
With commit d4c19cde("virtio-serial: add missing virtio_detach_element() call"), when virtio serial is throttled and closed by host, port->elem should be discard with virtqueue_push, otherwise virtqueue will not rewind, guest will blocked finally and cannot write anymore data. It can be reproduced with following steps: Create a vm with virtio-serial device through libvirt: <channel type='unix'> <source mode='bind' path='/tmp/test'/> <target type='virtio' name='com.test.channel.0'/> <address type='virtio-serial' controller='0' bus='0' port='1'/> </channel> Host run: watch -n0.5 'timeout 0.5 nc -U /tmp/test' Guest run: hexdump -C -v /dev/zero > /dev/vport1p1 After sometime, guest can not write any data to serial. We can see vq->last_avail_idx - vq->used_idx = 128 with gdb. (gdb) p *(struct VirtQueue *) 0x565161c5c788 $4 = {vring = {num = 128, num_default = 128, align = 4096, desc = 4316049408, avail = 4316051456, used = 4316051776, caches = 0x7fc530067e60}, used_elems = 0x565161c88dc0, last_avail_idx = 7929, last_avail_wrap_counter = true, shadow_avail_idx = 7929, shadow_avail_wrap_counter = true, used_idx = 7801, used_wrap_counter = true, signalled_used = 7801, signalled_used_valid = true, notification = true, queue_index = 5, inuse = 0, vector = 1, handle_output = 0x56515da8aea0 <handle_output>, handle_aio_output = 0x0, vdev = 0x565161c54e30, guest_notifier = {rfd = 0, wfd = 0}, host_notifier = {rfd = 74, wfd = 74}, host_notifier_enabled = true, node = {le_next = 0x565161c5c6f0, le_prev = 0x565161c5c8a8}} Fixes: d4c19cde("virtio-serial: add missing virtio_detach_element() call") Signed-off-by: Sun Feng <loyou85@gmail.com> --- hw/char/virtio-serial-bus.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)