On Mon, 7 Jan 2019 13:31:46 +0100 Halil Pasic <pasic@xxxxxxxxxxxxx> wrote: > A queue with a capacity of zero is clearly not a valid virtio queue. > Some emulators report zero queue size if queried with an invalid queue > index. Instead of crashing in this case let us just return -EINVAL. To s/-EINVAL/-ENOENT/ > make that work properly, let us fix the notifier cleanup logic as well. > > Signed-off-by: Halil Pasic <pasic@xxxxxxxxxxxxx> > --- > This patch is motivated by commit 86a5597 "virtio-balloon: > VIRTIO_BALLOON_F_FREE_PAGE_HINT" (Wei Wang, 2018-08-27) which triggered > the described scenario. The emulator in question is the current QEMU. > The problem we run into is the underflow in the following loop > in __vring_new_virtqueue(): > for (i = 0; i < vring.num-1; i++) > vq->vring.desc[i].next = cpu_to_virtio16(vdev, i + 1) > Namely vring.num is an unsigned int. > > RFC --> v1: > * Change error code from -EINVAL to -ENOENT, so we are in line with the > other transports. > * Push down the detection of the error into virtio_ccw_read_vq_conf(). > --- > drivers/s390/virtio/virtio_ccw.c | 4 +++- > 1 file changed, 3 insertions(+), 1 deletion(-) Thanks, applied.
