Re: [Xen-devel] [PATCH net-next 1/2] xen-netback: add a vif-is-connected flag

[Wei Liu <wei.liu2@xxxxxxxxxx>]

On Fri, Sep 20, 2013 at 01:56:30PM +0100, Paul Durrant wrote:
> Having applied my patch to separate vif disconnect and free, I ran into a
> BUG when testing resume from S3 with a Windows frontend because the vif task
> pointer was not cleared by xenvif_disconnect() and so a double call to this
> function tries to stop the thread twice.
> Rather than applying a point fix for that issue it seems better to introduce
> a boolean to indicate whether the vif is connected or not such that repeated
> calls to either xenvif_connect() or xenvif_disconnect() behave appropriately.
> 
> Signed-off-by: Paul Durrant <paul.durrant@xxxxxxxxxx>
> Cc: David Vrabel <david.vrabel@xxxxxxxxxx>
> Cc: Wei Liu <wei.liu2@xxxxxxxxxx>
> Cc: Ian Campbell <ian.campbell@xxxxxxxxxx>

Reasonable change.

Acked-by: Wei Liu <wei.liu2@xxxxxxxxxx>

Thanks
Wei.

> ---
>  drivers/net/xen-netback/common.h    |    1 +
>  drivers/net/xen-netback/interface.c |   24 +++++++++++++-----------
>  2 files changed, 14 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/net/xen-netback/common.h 
> b/drivers/net/xen-netback/common.h
> index 5715318..860d92c 100644
> --- a/drivers/net/xen-netback/common.h
> +++ b/drivers/net/xen-netback/common.h
> @@ -169,6 +169,7 @@ struct xenvif {
>  
>       /* Miscellaneous private stuff. */
>       struct net_device *dev;
> +     bool connected;
>  };
>  
>  static inline struct xenbus_device *xenvif_to_xenbus_device(struct xenvif 
> *vif)
> diff --git a/drivers/net/xen-netback/interface.c 
> b/drivers/net/xen-netback/interface.c
> index 01bb854..94b47f5 100644
> --- a/drivers/net/xen-netback/interface.c
> +++ b/drivers/net/xen-netback/interface.c
> @@ -366,7 +366,7 @@ int xenvif_connect(struct xenvif *vif, unsigned long 
> tx_ring_ref,
>       int err = -ENOMEM;
>  
>       /* Already connected through? */
> -     if (vif->tx_irq)
> +     if (vif->connected)
>               return 0;
>  
>       err = xenvif_map_frontend_rings(vif, tx_ring_ref, rx_ring_ref);
> @@ -425,6 +425,7 @@ int xenvif_connect(struct xenvif *vif, unsigned long 
> tx_ring_ref,
>  
>       wake_up_process(vif->task);
>  
> +     vif->connected = 1;
>       return 0;
>  
>  err_rx_unbind:
> @@ -453,23 +454,24 @@ void xenvif_carrier_off(struct xenvif *vif)
>  
>  void xenvif_disconnect(struct xenvif *vif)
>  {
> +     if (!vif->connected)
> +             return;
> +
>       if (netif_carrier_ok(vif->dev))
>               xenvif_carrier_off(vif);
>  
> -     if (vif->tx_irq) {
> -             if (vif->tx_irq == vif->rx_irq)
> -                     unbind_from_irqhandler(vif->tx_irq, vif);
> -             else {
> -                     unbind_from_irqhandler(vif->tx_irq, vif);
> -                     unbind_from_irqhandler(vif->rx_irq, vif);
> -             }
> -             vif->tx_irq = 0;
> +     if (vif->tx_irq == vif->rx_irq)
> +             unbind_from_irqhandler(vif->tx_irq, vif);
> +     else {
> +             unbind_from_irqhandler(vif->tx_irq, vif);
> +             unbind_from_irqhandler(vif->rx_irq, vif);
>       }
>  
> -     if (vif->task)
> -             kthread_stop(vif->task);
> +     kthread_stop(vif->task);
>  
>       xenvif_unmap_frontend_rings(vif);
> +
> +     vif->connected = 0;
>  }
>  
>  void xenvif_free(struct xenvif *vif)
> -- 
> 1.7.10.4

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