Re: [PATCH] vfio-ccw: Attempt to clean up all IRQs on error

[Cornelia Huck]

On Tue, 27 Apr 2021 16:25:11 +0200
Eric Farman <farman@linux.ibm.com> wrote:

> The vfio_ccw_unrealize() routine makes an unconditional attempt to
> unregister every IRQ notifier, though they may not have been registered
> in the first place (when running on an older kernel, for example).
> 
> Let's mirror this behavior in the error cleanups in vfio_ccw_realize()
> so that if/when new IRQs are added, it is less confusing to recognize
> the necessary procedures. The worst case scenario would be some extra
> messages about an undefined IRQ, but since this is an error exit that
> won't be the only thing to worry about.

I'm wondering whether we should downgrade the moan during unregister
from error to warn; the code deals with it gracefully, and we're not
losing any functionality.

Patch looks good.

> 
> Signed-off-by: Eric Farman <farman@linux.ibm.com>
> ---
>  hw/vfio/ccw.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/hw/vfio/ccw.c b/hw/vfio/ccw.c
> index 400bc07fe2..169438c3b8 100644
> --- a/hw/vfio/ccw.c
> +++ b/hw/vfio/ccw.c
> @@ -690,7 +690,7 @@ static void vfio_ccw_realize(DeviceState *dev, Error 
> **errp)
>      if (vcdev->crw_region) {
>          vfio_ccw_register_irq_notifier(vcdev, VFIO_CCW_CRW_IRQ_INDEX, &err);
>          if (err) {
> -            goto out_crw_notifier_err;
> +            goto out_irq_notifier_err;
>          }
>      }
>  
> @@ -705,7 +705,9 @@ static void vfio_ccw_realize(DeviceState *dev, Error 
> **errp)
>  
>      return;
>  
> -out_crw_notifier_err:
> +out_irq_notifier_err:
> +    vfio_ccw_unregister_irq_notifier(vcdev, VFIO_CCW_REQ_IRQ_INDEX);
> +    vfio_ccw_unregister_irq_notifier(vcdev, VFIO_CCW_CRW_IRQ_INDEX);
>      vfio_ccw_unregister_irq_notifier(vcdev, VFIO_CCW_IO_IRQ_INDEX);
>  out_io_notifier_err:
>      vfio_ccw_put_region(vcdev);