Re: [PATCH 07/18] xen/pvcalls: implement socket command

[Stefano Stabellini]

On Mon, 15 May 2017, Boris Ostrovsky wrote:
> On 05/15/2017 04:35 PM, Stefano Stabellini wrote:
> > Just reply with success to the other end for now. Delay the allocation
> > of the actual socket to bind and/or connect.
> > 
> > Signed-off-by: Stefano Stabellini <stefano@xxxxxxxxxxx>
> > CC: boris.ostrovsky@xxxxxxxxxx
> > CC: jgross@xxxxxxxx
> > ---
> >  drivers/xen/pvcalls-back.c | 31 ++++++++++++++++++++++++++++++-
> >  1 file changed, 30 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/xen/pvcalls-back.c b/drivers/xen/pvcalls-back.c
> > index 2b2a49a..2eae096 100644
> > --- a/drivers/xen/pvcalls-back.c
> > +++ b/drivers/xen/pvcalls-back.c
> > @@ -12,12 +12,17 @@
> >   * GNU General Public License for more details.
> >   */
> > 
> > +#include <linux/inet.h>
> >  #include <linux/kthread.h>
> >  #include <linux/list.h>
> >  #include <linux/radix-tree.h>
> >  #include <linux/module.h>
> >  #include <linux/rwsem.h>
> >  #include <linux/wait.h>
> > +#include <net/sock.h>
> > +#include <net/inet_common.h>
> > +#include <net/inet_connection_sock.h>
> > +#include <net/request_sock.h>
> > 
> >  #include <xen/events.h>
> >  #include <xen/grant_table.h>
> > @@ -65,7 +70,31 @@ static void pvcalls_back_ioworker(struct work_struct
> > *work)
> >  static int pvcalls_back_socket(struct xenbus_device *dev,
> >  		struct xen_pvcalls_request *req)
> >  {
> > -	return 0;
> > +	struct pvcalls_back_priv *priv;
> > +	int ret;
> > +	struct xen_pvcalls_response *rsp;
> > +
> > +	if (dev == NULL)
> > +		return 0;
> > +	priv = dev_get_drvdata(&dev->dev);
> 
> This is inconsistent with pvcalls_back_event() tests, where you check both for
> NULL. OTOH, I am not sure a check is needed at all since you've just tested
> these in pvcalls_back_event().

That's because priv cannot be NULL at this stage: it was allocated
before queuing any work to priv->wq. While in pvcalls_back_event I have
been more careful in case of spurious (erroneous) notifications.

I agree that I could remove this dev == NULL check here, and in the
other command handlers. I'll do that.


> > +
> > +	if (req->u.socket.domain != AF_INET ||
> > +	    req->u.socket.type != SOCK_STREAM ||
> > +	    (req->u.socket.protocol != 0 &&
> > +	     req->u.socket.protocol != AF_INET))
> > +		ret = -EAFNOSUPPORT;
> > +	else
> > +		ret = 0;
> > +
> > +	/* leave the actual socket allocation for later */
> > +
> > +	rsp = RING_GET_RESPONSE(&priv->ring, priv->ring.rsp_prod_pvt++);
> > +	rsp->req_id = req->req_id;
> > +	rsp->cmd = req->cmd;
> > +	rsp->u.socket.id = req->u.socket.id;
> > +	rsp->ret = ret;
> > +
> > +	return 1;
> >  }
> > 
> >  static int pvcalls_back_connect(struct xenbus_device *dev,
> > 
>