[net-next] xen-netback: only deinitialized hash if it was initialized

A domain with a frontend that does not implement a control ring has been
seen to cause a crash during domain save. This was apparently because
the call to xenvif_deinit_hash() in xenvif_disconnect_ctrl() is made
regardless of whether a control ring was connected, and hence
xenvif_hash_init() was called.

This patch brings the call to xenvif_deinit_hash() in
xenvif_disconnect_ctrl() inside the if clause that checks whether the
control ring event channel was connected. This is sufficient to ensure
it is only called if xenvif_init_hash() was called previously.

Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
Reported-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Tested-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Wei Liu <wei.liu2@citrix.com>
---
 drivers/net/xen-netback/interface.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

On Wed, May 18, 2016 at 03:55:42PM +0100, Paul Durrant wrote:
> A domain with a frontend that does not implement a control ring has been
> seen to cause a crash during domain save. This was apparently because
> the call to xenvif_deinit_hash() in xenvif_disconnect_ctrl() is made
> regardless of whether a control ring was connected, and hence
> xenvif_hash_init() was called.
> 
> This patch brings the call to xenvif_deinit_hash() in
> xenvif_disconnect_ctrl() inside the if clause that checks whether the
> control ring event channel was connected. This is sufficient to ensure
> it is only called if xenvif_init_hash() was called previously.
> 
> Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
> Reported-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
> Tested-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
> Cc: Wei Liu <wei.liu2@citrix.com>

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

> ---
>  drivers/net/xen-netback/interface.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/drivers/net/xen-netback/interface.c b/drivers/net/xen-netback/interface.c
> index 1c7f49b..83deeeb 100644
> --- a/drivers/net/xen-netback/interface.c
> +++ b/drivers/net/xen-netback/interface.c
> @@ -780,9 +780,8 @@ void xenvif_disconnect_ctrl(struct xenvif *vif)
>  		vif->ctrl_task = NULL;
>  	}
>  
> -	xenvif_deinit_hash(vif);
> -
>  	if (vif->ctrl_irq) {
> +		xenvif_deinit_hash(vif);
>  		unbind_from_irqhandler(vif->ctrl_irq, vif);
>  		vif->ctrl_irq = 0;
>  	}
> -- 
> 2.1.4
>

From: Paul Durrant <paul.durrant@citrix.com>
Date: Wed, 18 May 2016 15:55:42 +0100

> A domain with a frontend that does not implement a control ring has been
> seen to cause a crash during domain save. This was apparently because
> the call to xenvif_deinit_hash() in xenvif_disconnect_ctrl() is made
> regardless of whether a control ring was connected, and hence
> xenvif_hash_init() was called.
> 
> This patch brings the call to xenvif_deinit_hash() in
> xenvif_disconnect_ctrl() inside the if clause that checks whether the
> control ring event channel was connected. This is sufficient to ensure
> it is only called if xenvif_init_hash() was called previously.
> 
> Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
> Reported-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
> Tested-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>

Applied, thanks.