From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752192AbdGDG5j (ORCPT ); Tue, 4 Jul 2017 02:57:39 -0400 Received: from mx2.suse.de ([195.135.220.15]:45471 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751986AbdGDG5j (ORCPT ); Tue, 4 Jul 2017 02:57:39 -0400 Subject: Re: [PATCH v6 06/18] xen/pvcalls: handle commands from the frontend To: Stefano Stabellini , xen-devel@lists.xen.org Cc: linux-kernel@vger.kernel.org, boris.ostrovsky@oracle.com, Stefano Stabellini References: <1499116119-15638-1-git-send-email-sstabellini@kernel.org> <1499116119-15638-6-git-send-email-sstabellini@kernel.org> From: Juergen Gross Message-ID: Date: Tue, 4 Jul 2017 08:57:35 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.2.1 MIME-Version: 1.0 In-Reply-To: <1499116119-15638-6-git-send-email-sstabellini@kernel.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 03/07/17 23:08, Stefano Stabellini wrote: > When the other end notifies us that there are commands to be read > (pvcalls_back_event), wake up the backend thread to parse the command. > > The command ring works like most other Xen rings, so use the usual > ring macros to read and write to it. The functions implementing the > commands are empty stubs for now. > > Signed-off-by: Stefano Stabellini > CC: boris.ostrovsky@oracle.com > CC: jgross@suse.com > --- > drivers/xen/pvcalls-back.c | 144 ++++++++++++++++++++++++++++++++++++++++----- > 1 file changed, 129 insertions(+), 15 deletions(-) > > diff --git a/drivers/xen/pvcalls-back.c b/drivers/xen/pvcalls-back.c > index e4c2e46..9e00971 100644 > --- a/drivers/xen/pvcalls-back.c > +++ b/drivers/xen/pvcalls-back.c > @@ -47,16 +47,135 @@ struct pvcalls_fedata { > struct list_head socket_mappings; > struct radix_tree_root socketpass_mappings; > struct semaphore socket_lock; > - struct workqueue_struct *wq; > - struct work_struct register_work; > }; > > -static void pvcalls_back_work(struct work_struct *work) > +static int pvcalls_back_socket(struct xenbus_device *dev, > + struct xen_pvcalls_request *req) > { > + return 0; > +} > + > +static int pvcalls_back_connect(struct xenbus_device *dev, > + struct xen_pvcalls_request *req) > +{ > + return 0; > +} > + > +static int pvcalls_back_release(struct xenbus_device *dev, > + struct xen_pvcalls_request *req) > +{ > + return 0; > +} > + > +static int pvcalls_back_bind(struct xenbus_device *dev, > + struct xen_pvcalls_request *req) > +{ > + return 0; > +} > + > +static int pvcalls_back_listen(struct xenbus_device *dev, > + struct xen_pvcalls_request *req) > +{ > + return 0; > +} > + > +static int pvcalls_back_accept(struct xenbus_device *dev, > + struct xen_pvcalls_request *req) > +{ > + return 0; > +} > + > +static int pvcalls_back_poll(struct xenbus_device *dev, > + struct xen_pvcalls_request *req) > +{ > + return 0; > +} > + > +static int pvcalls_back_handle_cmd(struct xenbus_device *dev, > + struct xen_pvcalls_request *req) > +{ > + int ret = 0; > + > + switch (req->cmd) { > + case PVCALLS_SOCKET: > + ret = pvcalls_back_socket(dev, req); > + break; > + case PVCALLS_CONNECT: > + ret = pvcalls_back_connect(dev, req); > + break; > + case PVCALLS_RELEASE: > + ret = pvcalls_back_release(dev, req); > + break; > + case PVCALLS_BIND: > + ret = pvcalls_back_bind(dev, req); > + break; > + case PVCALLS_LISTEN: > + ret = pvcalls_back_listen(dev, req); > + break; > + case PVCALLS_ACCEPT: > + ret = pvcalls_back_accept(dev, req); > + break; > + case PVCALLS_POLL: > + ret = pvcalls_back_poll(dev, req); > + break; > + default: > + { > + struct pvcalls_fedata *fedata; > + struct xen_pvcalls_response *rsp; > + > + fedata = dev_get_drvdata(&dev->dev); > + rsp = RING_GET_RESPONSE( > + &fedata->ring, fedata->ring.rsp_prod_pvt++); > + rsp->req_id = req->req_id; > + rsp->cmd = req->cmd; > + rsp->ret = -ENOTSUPP; > + break; > + } > + } > + return ret; > +} > + > +static void pvcalls_back_work(struct pvcalls_fedata *fedata) > +{ > + int notify, notify_all = 0, more = 1; > + struct xen_pvcalls_request req; > + struct xenbus_device *dev = fedata->dev; > + > + while (more) { > + while (RING_HAS_UNCONSUMED_REQUESTS(&fedata->ring)) { > + RING_COPY_REQUEST(&fedata->ring, > + fedata->ring.req_cons++, > + &req); > + > + if (!pvcalls_back_handle_cmd(dev, &req)) { > + RING_PUSH_RESPONSES_AND_CHECK_NOTIFY( > + &fedata->ring, notify); > + notify_all += notify; > + } > + } > + > + if (notify_all) { > + notify_remote_via_irq(fedata->irq); > + notify_all = 0; > + } > + > + RING_FINAL_CHECK_FOR_REQUESTS(&fedata->ring, more); > + } > } > > static irqreturn_t pvcalls_back_event(int irq, void *dev_id) > { > + struct xenbus_device *dev = dev_id; > + struct pvcalls_fedata *fedata = NULL; > + > + if (dev == NULL) > + return IRQ_HANDLED; > + > + fedata = dev_get_drvdata(&dev->dev); > + if (fedata == NULL) > + return IRQ_HANDLED; > + > + pvcalls_back_work(fedata); > return IRQ_HANDLED; > } > > @@ -87,18 +206,15 @@ static int backend_connect(struct xenbus_device *dev) > goto error; > } > > - err = bind_interdomain_evtchn_to_irqhandler(dev->otherend_id, evtchn, > - pvcalls_back_event, 0, > - "pvcalls-backend", dev); > + err = bind_interdomain_evtchn_to_irq(dev->otherend_id, evtchn); > if (err < 0) > goto error; > fedata->irq = err; > - > - fedata->wq = alloc_workqueue("pvcalls_back_wq", WQ_UNBOUND, 1); > - if (!fedata->wq) { > - err = -ENOMEM; > + > + err = request_threaded_irq(fedata->irq, NULL, pvcalls_back_event, > + IRQF_ONESHOT, "pvcalls-back", dev); > + if (err < 0) > goto error; > - } > > err = xenbus_map_ring_valloc(dev, &ring_ref, 1, (void**)&fedata->sring); > if (err < 0) > @@ -107,7 +223,6 @@ static int backend_connect(struct xenbus_device *dev) > BACK_RING_INIT(&fedata->ring, fedata->sring, XEN_PAGE_SIZE * 1); > fedata->dev = dev; > > - INIT_WORK(&fedata->register_work, pvcalls_back_work); > INIT_LIST_HEAD(&fedata->socket_mappings); > INIT_RADIX_TREE(&fedata->socketpass_mappings, GFP_KERNEL); > sema_init(&fedata->socket_lock, 1); > @@ -116,15 +231,14 @@ static int backend_connect(struct xenbus_device *dev) > down(&pvcalls_back_global.frontends_lock); > list_add_tail(&fedata->list, &pvcalls_back_global.frontends); > up(&pvcalls_back_global.frontends_lock); > - queue_work(fedata->wq, &fedata->register_work); > + > + pvcalls_back_work(fedata); Is this call really necessary? I believe this is racy in case an event is coming in at the same time. > > return 0; > > error: > if (fedata->sring != NULL) > xenbus_unmap_ring_vfree(dev, fedata->sring); > - if (fedata->wq) > - destroy_workqueue(fedata->wq); > unbind_from_irqhandler(fedata->irq, dev); Is it secure to unbind the irq handler _after_ unmapping the ring? Juergen