Re: [Qemu-devel] [PULL 4/6] vfio-ccw: use vfio_set_irq_signaling

[Peter Maydell]

On Mon, 1 Jul 2019 at 12:17, Cornelia Huck <address@hidden> wrote:
>
> Use the new helper.
>
> Reviewed-by: Eric Auger <address@hidden>
> Reviewed-by: Eric Farman <address@hidden>
> Message-Id: <address@hidden>
> Signed-off-by: Cornelia Huck <address@hidden>

Coverity complains about this patch (CID 1402783), though
it's arguably a bit of a false-positive.

> +    if (vfio_set_irq_signaling(vdev, VFIO_CCW_IO_IRQ_INDEX, 0,
> +                               VFIO_IRQ_SET_ACTION_TRIGGER, fd, errp)) {
> +        qemu_set_fd_handler(fd, NULL, NULL, vcdev);
>          event_notifier_cleanup(&vcdev->io_notifier);
>      }

Here we check "did vfio_set_irq_signaling() fail" by looking
at its return value...

>
> -    g_free(irq_set);
> -
>  out_free_info:
>      g_free(irq_info);
>  }
>
>  static void vfio_ccw_unregister_io_notifier(VFIOCCWDevice *vcdev)
>  {
> -    struct vfio_irq_set *irq_set;
> -    size_t argsz;
> -    int32_t *pfd;
> -
> -    argsz = sizeof(*irq_set) + sizeof(*pfd);
> -    irq_set = g_malloc0(argsz);
> -    irq_set->argsz = argsz;
> -    irq_set->flags = VFIO_IRQ_SET_DATA_EVENTFD |
> -                     VFIO_IRQ_SET_ACTION_TRIGGER;
> -    irq_set->index = VFIO_CCW_IO_IRQ_INDEX;
> -    irq_set->start = 0;
> -    irq_set->count = 1;
> -    pfd = (int32_t *) &irq_set->data;
> -    *pfd = -1;
> -
> -    if (ioctl(vcdev->vdev.fd, VFIO_DEVICE_SET_IRQS, irq_set)) {
> -        error_report("vfio: Failed to de-assign device io fd: %m");
> +    Error *err = NULL;
> +
> +    vfio_set_irq_signaling(&vcdev->vdev, VFIO_CCW_IO_IRQ_INDEX, 0,
> +                           VFIO_IRQ_SET_ACTION_TRIGGER, -1, &err);
> +    if (err) {
> +        error_reportf_err(err, VFIO_MSG_PREFIX, vcdev->vdev.name);
>      }

...but here we look at the err parameter. This makes Coverity
unhappy because its heuristic says "we check the return value
from the function 8 times out of 10 so it's probably a bug
that we don't do that here". We could make it happy by using
the same way of checking for failure in both cases.

thanks
-- PMM