Re: [Qemu-devel] [PATCH] virtio-scsi: Allocate op blocker reason before blocking

[Fam Zheng]

On Mon, 02/23 17:58, Max Reitz wrote:
> s->blocker is really only used in hw/scsi/virtio-scsi.c; the only places
> where it is used in hw/scsi/virtio-scsi-dataplane.c is when it is
> allocated and when it is freed. That does not make a whole lot of sense
> (and is actually wrong because this leads to s->blocker potentially
> being NULL when blk_op_block_all() is called in virtio-scsi.c), so move
> the allocation and destruction of s->blocker to blk_op_block_all() and
> blk_op_unblock_all() in virtio-scsi.c, respectively.
> 
> Signed-off-by: Max Reitz <address@hidden>
> ---
> Try:
> 
> $ echo -e 'eject drv\nquit' | \
>     x86_64-softmmu/qemu-system-x86_64 \
>         -monitor stdio -machine accel=qtest -display none \
>         -object iothread,id=thr -device virtio-scsi-pci,iothread=thr \
>         -drive if=none,file=test.qcow2,format=qcow2,id=drv \
>         -device scsi-cd,drive=drv
> 
> What it should do:
> 
> QEMU 2.2.50 monitor - type 'help' for more information
> (qemu) eject drv
> Device 'drv' is busy: block device is in use by data plane
> (qemu) quit
> 
> What it should not do:
> 
> QEMU 2.2.50 monitor - type 'help' for more information
> (qemu) eject drv
> [1]    10102 done
>        10103 segmentation fault (core dumped)
> ---
>  hw/scsi/virtio-scsi-dataplane.c | 4 ----
>  hw/scsi/virtio-scsi.c           | 6 +++++-
>  2 files changed, 5 insertions(+), 5 deletions(-)
> 
> diff --git a/hw/scsi/virtio-scsi-dataplane.c b/hw/scsi/virtio-scsi-dataplane.c
> index 03a1e8c..9b775d4 100644
> --- a/hw/scsi/virtio-scsi-dataplane.c
> +++ b/hw/scsi/virtio-scsi-dataplane.c
> @@ -211,8 +211,6 @@ void virtio_scsi_dataplane_start(VirtIOSCSI *s)
>  
>      s->dataplane_starting = true;
>  
> -    assert(!s->blocker);
> -    error_setg(&s->blocker, "block device is in use by data plane");
>      /* Set up guest notifier (irq) */
>      rc = k->set_guest_notifiers(qbus->parent, vs->conf.num_queues + 2, true);
>      if (rc != 0) {
> @@ -279,8 +277,6 @@ void virtio_scsi_dataplane_stop(VirtIOSCSI *s)
>      if (!s->dataplane_started || s->dataplane_stopping) {
>          return;
>      }
> -    error_free(s->blocker);
> -    s->blocker = NULL;
>      s->dataplane_stopping = true;
>      assert(s->ctx == iothread_get_aio_context(vs->conf.iothread));
>  
> diff --git a/hw/scsi/virtio-scsi.c b/hw/scsi/virtio-scsi.c
> index 9e2c718..5469bad 100644
> --- a/hw/scsi/virtio-scsi.c
> +++ b/hw/scsi/virtio-scsi.c
> @@ -766,6 +766,8 @@ static void virtio_scsi_hotplug(HotplugHandler 
> *hotplug_dev, DeviceState *dev,
>          if (blk_op_is_blocked(sd->conf.blk, BLOCK_OP_TYPE_DATAPLANE, errp)) {
>              return;
>          }
> +        assert(!s->blocker);
> +        error_setg(&s->blocker, "block device is in use by data plane");
>          blk_op_block_all(sd->conf.blk, s->blocker);
>      }
>  
> @@ -789,8 +791,10 @@ static void virtio_scsi_hotunplug(HotplugHandler 
> *hotplug_dev, DeviceState *dev,
>                                 VIRTIO_SCSI_EVT_RESET_REMOVED);
>      }
>  
> -    if (s->ctx) {
> +    if (s->ctx && s->blocker) {
>          blk_op_unblock_all(sd->conf.blk, s->blocker);
> +        error_free(s->blocker);
> +        s->blocker = NULL;
>      }
>      qdev_simple_device_unplug_cb(hotplug_dev, dev, errp);
>  }
> -- 
> 2.1.0
> 
> 

Reviewed-by: Fam Zheng <address@hidden>