Messages in this thread | | | From | Boris Ostrovsky <> | Subject | Re: [PATCH v2 04/18] xen/pvcalls: xenbus state handling | Date | Thu, 25 May 2017 20:12:04 -0400 |
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On 05/19/2017 07:22 PM, Stefano Stabellini wrote: > Introduce the code to handle xenbus state changes. > > Implement the probe function for the pvcalls backend. Write the > supported versions, max-page-order and function-calls nodes to xenstore, > as required by the protocol. > > Introduce stub functions for disconnecting/connecting to a frontend. > > Signed-off-by: Stefano Stabellini <stefano@aporeto.com> > CC: boris.ostrovsky@oracle.com > CC: jgross@suse.com > --- > drivers/xen/pvcalls-back.c | 135 +++++++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 135 insertions(+) > > diff --git a/drivers/xen/pvcalls-back.c b/drivers/xen/pvcalls-back.c > index 9044cf2..b4da138 100644 > --- a/drivers/xen/pvcalls-back.c > +++ b/drivers/xen/pvcalls-back.c > @@ -25,20 +25,155 @@ > #include <xen/xenbus.h> > #include <xen/interface/io/pvcalls.h> > > +#define PVCALLS_VERSIONS "1"
Shouldn't this be in a header file that will be shared with frontends?
> +#define MAX_RING_ORDER XENBUS_MAX_RING_GRANT_ORDER > + > struct pvcalls_back_global { > struct list_head frontends; > struct semaphore frontends_lock; > } pvcalls_back_global; > > +static int backend_connect(struct xenbus_device *dev) > +{ > + return 0; > +} > + > +static int backend_disconnect(struct xenbus_device *dev) > +{ > + return 0; > +} > + > static int pvcalls_back_probe(struct xenbus_device *dev, > const struct xenbus_device_id *id) > { > + int err; > + > + err = xenbus_printf(XBT_NIL, dev->nodename, "versions", "%s", > + PVCALLS_VERSIONS); > + if (err) { > + pr_warn("%s write out 'version' failed\n", __func__); > + return -EINVAL;
err?
> + } > + > + err = xenbus_printf(XBT_NIL, dev->nodename, "max-page-order", "%u", > + MAX_RING_ORDER); > + if (err) { > + pr_warn("%s write out 'max-page-order' failed\n", __func__); > + return err; > + } > + > + /* "1" means socket, connect, release, bind, listen, accept and poll*/
This comment is obsolete, or at least should refer to XENBUS_FUNCTIONS_CALLS (and is missing a space at the end).
> + err = xenbus_printf(XBT_NIL, dev->nodename, "function-calls", > + XENBUS_FUNCTIONS_CALLS); > + if (err) { > + pr_warn("%s write out 'function-calls' failed\n", __func__); > + return err; > + }
In case of errors we will end up with all previous entries. I think this should be done as a transaction which would be aborted in case of an error.
> + > + err = xenbus_switch_state(dev, XenbusStateInitWait); > + if (err) > + return err;
Not sure what to do on an error here (wrt xenstore entries). xenbus_switch_state() itself uses transactions. Are we allowed to have nested transactions?
OTOH, xenbus_switch_state() never returns an error, at least now. In fact, in most cases we ignore return value.
-boris
> + > return 0; > } > >
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