From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751479AbdEPBsZ (ORCPT ); Mon, 15 May 2017 21:48:25 -0400 Received: from userp1040.oracle.com ([156.151.31.81]:51193 "EHLO userp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751227AbdEPBsY (ORCPT ); Mon, 15 May 2017 21:48:24 -0400 Subject: Re: [PATCH 04/18] xen/pvcalls: xenbus state handling To: Stefano Stabellini , xen-devel@lists.xen.org References: <1494880570-14209-1-git-send-email-sstabellini@kernel.org> <1494880570-14209-4-git-send-email-sstabellini@kernel.org> Cc: linux-kernel@vger.kernel.org, jgross@suse.com, Stefano Stabellini From: Boris Ostrovsky Message-ID: <02e0fa9d-4cd9-ae74-868c-27538736c68f@oracle.com> Date: Mon, 15 May 2017 21:34:49 -0400 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.8.0 MIME-Version: 1.0 In-Reply-To: <1494880570-14209-4-git-send-email-sstabellini@kernel.org> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit X-Source-IP: aserv0022.oracle.com [141.146.126.234] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 05/15/2017 04:35 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 > CC: boris.ostrovsky@oracle.com > CC: jgross@suse.com > --- > drivers/xen/pvcalls-back.c | 133 +++++++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 133 insertions(+) > > diff --git a/drivers/xen/pvcalls-back.c b/drivers/xen/pvcalls-back.c > index 46a889a..86eca19 100644 > --- a/drivers/xen/pvcalls-back.c > +++ b/drivers/xen/pvcalls-back.c > @@ -25,6 +25,9 @@ > #include > #include > > +#define PVCALLS_VERSIONS "1" > +#define MAX_RING_ORDER XENBUS_MAX_RING_GRANT_ORDER > + > struct pvcalls_ioworker { > struct work_struct register_work; > atomic_t io; > @@ -45,15 +48,145 @@ static void pvcalls_back_ioworker(struct work_struct *work) > { > } > > +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; Why not return err? (below too) > + } > + > + 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 -EINVAL; > + } > + > + /* "1" means socket, connect, release, bind, listen, accept and poll*/ > + err = xenbus_printf(XBT_NIL, dev->nodename, "function-calls", "1"); Should "1" be defined in the (public) header file? > + if (err) { > + pr_warn("%s write out 'function-calls' failed\n", __func__); > + return -EINVAL; > + } > + > + err = xenbus_switch_state(dev, XenbusStateInitWait); > + if (err) > + return err; > + > return 0; > } > > +static void set_backend_state(struct xenbus_device *dev, > + enum xenbus_state state) > +{ > + while (dev->state != state) { > + switch (dev->state) { > + case XenbusStateClosed: > + switch (state) { > + case XenbusStateInitWait: > + case XenbusStateConnected: > + xenbus_switch_state(dev, XenbusStateInitWait); > + break; > + case XenbusStateClosing: > + xenbus_switch_state(dev, XenbusStateClosing); > + break; > + default: > + __WARN(); > + } > + break; > + case XenbusStateInitWait: > + case XenbusStateInitialised: > + switch (state) { > + case XenbusStateConnected: > + backend_connect(dev); > + xenbus_switch_state(dev, XenbusStateConnected); > + break; > + case XenbusStateClosing: > + case XenbusStateClosed: > + xenbus_switch_state(dev, XenbusStateClosing); > + break; > + default: > + __WARN(); > + } > + break; > + case XenbusStateConnected: > + switch (state) { > + case XenbusStateInitWait: > + case XenbusStateClosing: > + case XenbusStateClosed: > + down_write(&pvcalls_back_global.privs_lock); > + backend_disconnect(dev); > + up_write(&pvcalls_back_global.privs_lock); Unless you plan to have more stuff under the semaphore, I'd consider putting them in backend_disconnect(). > + xenbus_switch_state(dev, XenbusStateClosing); > + break; > + default: > + __WARN(); > + } > + break; > + case XenbusStateClosing: > + switch (state) { > + case XenbusStateInitWait: > + case XenbusStateConnected: > + case XenbusStateClosed: > + xenbus_switch_state(dev, XenbusStateClosed); > + break; > + default: > + __WARN(); > + } > + break; > + default: > + __WARN(); > + } > + } > +} > + > static void pvcalls_back_changed(struct xenbus_device *dev, > enum xenbus_state frontend_state) > { > + switch (frontend_state) { > + case XenbusStateInitialising: > + set_backend_state(dev, XenbusStateInitWait); > + break; > + > + case XenbusStateInitialised: > + case XenbusStateConnected: > + set_backend_state(dev, XenbusStateConnected); > + break; > + > + case XenbusStateClosing: > + set_backend_state(dev, XenbusStateClosing); > + break; > + > + case XenbusStateClosed: > + set_backend_state(dev, XenbusStateClosed); > + if (xenbus_dev_is_online(dev)) > + break; > + /* fall through if not online */ > + case XenbusStateUnknown: > + set_backend_state(dev, XenbusStateClosed); You are setting XenbusStateClosed twice in case of fallthrough. -boris > + device_unregister(&dev->dev); > + break; > + > + default: > + xenbus_dev_fatal(dev, -EINVAL, "saw state %d at frontend", > + frontend_state); > + break; > + } > } > > static int pvcalls_back_remove(struct xenbus_device *dev) >