linux-kernel - Re: [PATCH v3 13/18] xen/pvcalls: implement release command

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Message-ID: <18386730-7ef1-ed3e-0a0d-845bd8cbb8ef@suse.com>
Date:   Tue, 13 Jun 2017 09:39:39 +0200
From:   Juergen Gross <jgross@...e.com>
To:     Stefano Stabellini <sstabellini@...nel.org>,
        xen-devel@...ts.xen.org
Cc:     linux-kernel@...r.kernel.org, boris.ostrovsky@...cle.com,
        Stefano Stabellini <stefano@...reto.com>
Subject: Re: [PATCH v3 13/18] xen/pvcalls: implement release command

On 02/06/17 21:31, Stefano Stabellini wrote:
> Release both active and passive sockets. For active sockets, make sure
> to avoid possible conflicts with the ioworker reading/writing to those
> sockets concurrently. Set map->release to let the ioworker know
> atomically that the socket will be released soon, then wait until the
> ioworker finishes (flush_work).
> 
> Unmap indexes pages and data rings.
> 
> Signed-off-by: Stefano Stabellini <stefano@...reto.com>
> CC: boris.ostrovsky@...cle.com
> CC: jgross@...e.com
> ---
>  drivers/xen/pvcalls-back.c | 72 +++++++++++++++++++++++++++++++++++++++++++++-
>  1 file changed, 71 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/xen/pvcalls-back.c b/drivers/xen/pvcalls-back.c
> index 82f350d..b541887 100644
> --- a/drivers/xen/pvcalls-back.c
> +++ b/drivers/xen/pvcalls-back.c
> @@ -265,13 +265,83 @@ static int pvcalls_back_release_active(struct xenbus_device *dev,
>  				       struct pvcalls_fedata *priv,
>  				       struct sock_mapping *map)
>  {
> +	disable_irq(map->irq);
> +	if (map->sock->sk != NULL) {
> +		write_lock_bh(&map->sock->sk->sk_callback_lock);
> +		map->sock->sk->sk_user_data = NULL;
> +		map->sock->sk->sk_data_ready = map->saved_data_ready;
> +		write_unlock_bh(&map->sock->sk->sk_callback_lock);
> +	}
> +
> +	atomic_set(&map->release, 1);
> +	flush_work(&map->ioworker.register_work);
> +
> +	down(&priv->socket_lock);
> +	list_del(&map->list);
> +	up(&priv->socket_lock);
> +
> +	xenbus_unmap_ring_vfree(dev, (void *)map->bytes);
> +	xenbus_unmap_ring_vfree(dev, (void *)map->ring);

I don't think you need the casts to (void*) here.

> +	unbind_from_irqhandler(map->irq, map);
> +
> +	sock_release(map->sock);
> +	kfree(map);
> +
> +	return 0;
> +}
> +
> +static int pvcalls_back_release_passive(struct xenbus_device *dev,
> +					struct pvcalls_fedata *priv,
> +					struct sockpass_mapping *mappass)
> +{
> +	if (mappass->sock->sk != NULL) {
> +		write_lock_bh(&mappass->sock->sk->sk_callback_lock);
> +		mappass->sock->sk->sk_user_data = NULL;
> +		mappass->sock->sk->sk_data_ready = mappass->saved_data_ready;
> +		write_unlock_bh(&mappass->sock->sk->sk_callback_lock);
> +	}
> +	down(&priv->socket_lock);
> +	radix_tree_delete(&priv->socketpass_mappings, mappass->id);
> +	sock_release(mappass->sock);
> +	flush_workqueue(mappass->wq);
> +	destroy_workqueue(mappass->wq);
> +	kfree(mappass);
> +	up(&priv->socket_lock);
> +
>  	return 0;
>  }
>  
>  static int pvcalls_back_release(struct xenbus_device *dev,
>  				struct xen_pvcalls_request *req)
>  {
> -	return 0;
> +	struct pvcalls_fedata *priv;
> +	struct sock_mapping *map, *n;
> +	struct sockpass_mapping *mappass;
> +	int ret = 0;
> +	struct xen_pvcalls_response *rsp;
> +
> +	priv = dev_get_drvdata(&dev->dev);
> +
> +	list_for_each_entry_safe(map, n, &priv->socket_mappings, list) {
> +		if (map->id == req->u.release.id) {
> +			ret = pvcalls_back_release_active(dev, priv, map);
> +			goto out;
> +		}
> +	}
> +	mappass = radix_tree_lookup(&priv->socketpass_mappings,
> +				    req->u.release.id);
> +	if (mappass != NULL) {
> +		ret = pvcalls_back_release_passive(dev, priv, mappass);
> +		goto out;
> +	}
> +
> +out:
> +	rsp = RING_GET_RESPONSE(&priv->ring, priv->ring.rsp_prod_pvt++);
> +	rsp->req_id = req->req_id;
> +	rsp->u.release.id = req->u.release.id;
> +	rsp->cmd = req->cmd;
> +	rsp->ret = ret;
> +	return ret;

return 0;


Juergen

>  }
>  
>  static void __pvcalls_back_accept(struct work_struct *work)
>