On 14/03/2017 14:26, Fam Zheng wrote:
> After the AioContext lock push down, there is a race between
> virtio_scsi_dataplane_start and those "assert(s->ctx &&
> s->dataplane_started)", because the latter doesn't isn't wrapped in
> aio_context_acquire.
>
> Reproducer is simply booting a Fedora guest with an empty
> virtio-scsi-dataplane controller:
>
> qemu-system-x86_64 \
> -drive
> if=none,id=root,format=raw,file=Fedora-Cloud-Base-25-1.3.x86_64.raw \
> -device virtio-scsi \
> -device scsi-disk,drive=root,bootindex=1 \
> -object iothread,id=io \
> -device virtio-scsi-pci,iothread=io \
> -net user,hostfwd=tcp::10022-:22 -net nic,model=virtio -m 2048 \
> --enable-kvm
>
> Signed-off-by: Fam Zheng <[email protected]>
> ---
> hw/scsi/virtio-scsi-dataplane.c | 20 ++++++++++++++++----
> 1 file changed, 16 insertions(+), 4 deletions(-)
>
> diff --git a/hw/scsi/virtio-scsi-dataplane.c b/hw/scsi/virtio-scsi-dataplane.c
> index 74c95e0..12b44b7 100644
> --- a/hw/scsi/virtio-scsi-dataplane.c
> +++ b/hw/scsi/virtio-scsi-dataplane.c
> @@ -52,28 +52,40 @@ void virtio_scsi_dataplane_setup(VirtIOSCSI *s, Error
> **errp)
> static bool virtio_scsi_data_plane_handle_cmd(VirtIODevice *vdev,
> VirtQueue *vq)
> {
> - VirtIOSCSI *s = (VirtIOSCSI *)vdev;
> + bool progress;
> + VirtIOSCSI *s = VIRTIO_SCSI(vdev);
>
> + aio_context_acquire(s->ctx);
> assert(s->ctx && s->dataplane_started);
> - return virtio_scsi_handle_cmd_vq(s, vq);
> + progress = virtio_scsi_handle_cmd_vq(s, vq);
> + aio_context_release(s->ctx);
Can you use virtio_scsi_acquire/release, and remove it from
virtio_scsi_handle_*_vq?
Paolo
> + return progress;
> }
>
> static bool virtio_scsi_data_plane_handle_ctrl(VirtIODevice *vdev,
> VirtQueue *vq)
> {
> + bool progress;
> VirtIOSCSI *s = VIRTIO_SCSI(vdev);
>
> + aio_context_acquire(s->ctx);
> assert(s->ctx && s->dataplane_started);
> - return virtio_scsi_handle_ctrl_vq(s, vq);
> + progress = virtio_scsi_handle_ctrl_vq(s, vq);
> + aio_context_release(s->ctx);
> + return progress;
> }
>
> static bool virtio_scsi_data_plane_handle_event(VirtIODevice *vdev,
> VirtQueue *vq)
> {
> + bool progress;
> VirtIOSCSI *s = VIRTIO_SCSI(vdev);
>
> + aio_context_acquire(s->ctx);
> assert(s->ctx && s->dataplane_started);
> - return virtio_scsi_handle_event_vq(s, vq);
> + progress = virtio_scsi_handle_event_vq(s, vq);
> + aio_context_release(s->ctx);
> + return progress;
> }
>
> static int virtio_scsi_vring_init(VirtIOSCSI *s, VirtQueue *vq, int n,
>
