From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750942AbdCNGlv (ORCPT ); Tue, 14 Mar 2017 02:41:51 -0400 Received: from mx2.suse.de ([195.135.220.15]:52565 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750726AbdCNGlu (ORCPT ); Tue, 14 Mar 2017 02:41:50 -0400 Subject: Re: [PATCH v3 4/7] xen/9pfs: connect to the backend To: Stefano Stabellini , xen-devel@lists.xenproject.org References: <1489449019-13343-1-git-send-email-sstabellini@kernel.org> <1489449019-13343-4-git-send-email-sstabellini@kernel.org> Cc: linux-kernel@vger.kernel.org, boris.ostrovsky@oracle.com, Stefano Stabellini , Eric Van Hensbergen , Ron Minnich , Latchesar Ionkov , v9fs-developer@lists.sourceforge.net From: Juergen Gross Message-ID: Date: Tue, 14 Mar 2017 07:41:46 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.7.0 MIME-Version: 1.0 In-Reply-To: <1489449019-13343-4-git-send-email-sstabellini@kernel.org> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 14/03/17 00:50, Stefano Stabellini wrote: > Implement functions to handle the xenbus handshake. Upon connection, > allocate the rings according to the protocol specification. > > Initialize a work_struct and a wait_queue. The work_struct will be used > to schedule work upon receiving an event channel notification from the > backend. The wait_queue will be used to wait when the ring is full and > we need to send a new request. > > Signed-off-by: Stefano Stabellini > CC: boris.ostrovsky@oracle.com > CC: jgross@suse.com > CC: Eric Van Hensbergen > CC: Ron Minnich > CC: Latchesar Ionkov > CC: v9fs-developer@lists.sourceforge.net > --- > net/9p/trans_xen.c | 240 +++++++++++++++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 240 insertions(+) > > diff --git a/net/9p/trans_xen.c b/net/9p/trans_xen.c > index f072876..974bac3 100644 > --- a/net/9p/trans_xen.c > +++ b/net/9p/trans_xen.c > @@ -41,6 +41,35 @@ > #include > #include > > +#define XEN_9PFS_NUM_RINGS 2 > + > +/* One per ring, more than one per 9pfs share */ > +struct xen_9pfs_dataring { > + struct xen_9pfs_front_priv *priv; > + > + struct xen_9pfs_data_intf *intf; > + grant_ref_t ref; > + int evtchn; > + int irq; > + spinlock_t lock; > + > + struct xen_9pfs_data data; > + wait_queue_head_t wq; > + struct work_struct work; > +}; > + > +/* One per 9pfs share */ > +struct xen_9pfs_front_priv { > + struct list_head list; > + struct xenbus_device *dev; > + char *tag; > + struct p9_client *client; > + > + int num_rings; > + struct xen_9pfs_dataring *rings; > +}; > +static LIST_HEAD(xen_9pfs_devs); > + > static int p9_xen_cancel(struct p9_client *client, struct p9_req_t *req) > { > return 0; > @@ -60,6 +89,21 @@ static int p9_xen_request(struct p9_client *client, struct p9_req_t *p9_req) > return 0; > } > > +static void p9_xen_response(struct work_struct *work) > +{ > +} > + > +static irqreturn_t xen_9pfs_front_event_handler(int irq, void *r) > +{ > + struct xen_9pfs_dataring *ring = r; > + BUG_ON(!ring || !ring->priv->client); > + > + wake_up_interruptible(&ring->wq); > + schedule_work(&ring->work); > + > + return IRQ_HANDLED; > +} > + > static struct p9_trans_module p9_xen_trans = { > .name = "xen", > .maxsize = (1 << (XEN_9PFS_RING_ORDER + XEN_PAGE_SHIFT)), > @@ -76,25 +120,221 @@ static int p9_xen_request(struct p9_client *client, struct p9_req_t *p9_req) > { "" } > }; > > +static int xen_9pfs_front_free(struct xen_9pfs_front_priv *priv) Return type void? You are always returning 0. > +{ > + int i, j; > + > + list_del(&priv->list); > + > + for (i = 0; i < priv->num_rings; i++) { > + if (priv->rings[i].intf == NULL) > + break; > + if (priv->rings[i].irq > 0) > + unbind_from_irqhandler(priv->rings[i].irq, priv->dev); > + if (priv->rings[i].data.in != NULL) { > + for (j = 0; j < (1 << XEN_9PFS_RING_ORDER); j++) > + gnttab_end_foreign_access(priv->rings[i].intf->ref[j], 0, 0); > + free_pages((unsigned long)priv->rings[i].data.in, > + XEN_9PFS_RING_ORDER - (PAGE_SHIFT - XEN_PAGE_SHIFT)); > + } > + gnttab_end_foreign_access(priv->rings[i].ref, 0, 0); > + free_page((unsigned long)priv->rings[i].intf); > + } > + kfree(priv->rings); > + kfree(priv); > + > + return 0; > +} > + > static int xen_9pfs_front_remove(struct xenbus_device *dev) > { > + int ret; > + struct xen_9pfs_front_priv *priv = dev_get_drvdata(&dev->dev); > + > + dev_set_drvdata(&dev->dev, NULL); > + ret = xen_9pfs_front_free(priv); > + return ret; > +} > + > +static int xen_9pfs_front_alloc_dataring(struct xenbus_device *dev, > + struct xen_9pfs_dataring *ring) > +{ > + int i = 0; > + int ret = -ENOMEM; > + void *bytes = NULL; > + > + init_waitqueue_head(&ring->wq); > + spin_lock_init(&ring->lock); > + INIT_WORK(&ring->work, p9_xen_response); > + > + ring->intf = (struct xen_9pfs_data_intf *) get_zeroed_page(GFP_KERNEL | __GFP_ZERO); I don't think you need __GFP_ZERO here. > + if (!ring->intf) > + return ret; > + ret = ring->ref = gnttab_grant_foreign_access(dev->otherend_id, > + virt_to_gfn(ring->intf), 0); > + if (ret < 0) > + goto out; > + bytes = (void*)__get_free_pages(GFP_KERNEL | __GFP_ZERO, Coding style: (void *) > + XEN_9PFS_RING_ORDER - (PAGE_SHIFT - XEN_PAGE_SHIFT)); > + if (bytes == NULL) > + goto out; > + for (; i < (1 << XEN_9PFS_RING_ORDER); i++) { > + ret = ring->intf->ref[i] = gnttab_grant_foreign_access( > + dev->otherend_id, virt_to_gfn(bytes) + i, 0); > + if (ret < 0) > + goto out; > + } > + ring->data.in = bytes; > + ring->data.out = bytes + XEN_9PFS_RING_SIZE; > + > + ret = xenbus_alloc_evtchn(dev, &ring->evtchn); > + if (ret) > + goto out; > + ring->irq = bind_evtchn_to_irqhandler(ring->evtchn, xen_9pfs_front_event_handler, > + 0, "xen_9pfs-frontend", ring); Did you think about using request_threaded_irq() instead of a workqueue? For an example see e.g. drivers/scsi/xen-scsifront.c > + if (ring->irq < 0) { > + xenbus_free_evtchn(dev, ring->evtchn); > + ret = ring->irq; > + goto out; > + } > return 0; > + > +out: > + if (bytes != NULL) { > + for (i--; i >= 0; i--) > + gnttab_end_foreign_access(ring->intf->ref[i], 0, 0); > + free_pages((unsigned long)bytes, > + XEN_9PFS_RING_ORDER - (PAGE_SHIFT - XEN_PAGE_SHIFT)); > + } > + gnttab_end_foreign_access(ring->ref, 0, 0); > + free_page((unsigned long)ring->intf); > + return ret; > } > > static int xen_9pfs_front_probe(struct xenbus_device *dev, > const struct xenbus_device_id *id) > { > + int ret, i; > + struct xenbus_transaction xbt; > + struct xen_9pfs_front_priv *priv = NULL; > + char *versions; > + unsigned int max_rings, max_ring_order, len; > + > + versions = xenbus_read(XBT_NIL, dev->otherend, "versions", &len); > + if (!len || strcmp(versions, "1")) You are leaking versions in case of not being "1". Can't you use xenbus_read_unsigned() instead of xenbus_read()? > + return -EINVAL; > + kfree(versions); > + ret = xenbus_scanf(XBT_NIL, dev->otherend, "max-rings", "%u", &max_rings); xenbus_read_unsigned()? > + if (ret < 0 || max_rings < XEN_9PFS_NUM_RINGS) > + return -EINVAL; > + ret = xenbus_scanf(XBT_NIL, dev->otherend, "max-ring-page-order", "%u", &max_ring_order); xenbus_read_unsigned() > + if (ret < 0|| max_ring_order < XEN_9PFS_RING_ORDER) Coding style (missing space before ||) > + return -EINVAL; > + > + > + priv = kzalloc(sizeof(struct xen_9pfs_front_priv), GFP_KERNEL); > + if (!priv) > + return -ENOMEM; > + > + priv->dev = dev; > + priv->num_rings = XEN_9PFS_NUM_RINGS; > + priv->rings = kzalloc(sizeof(struct xen_9pfs_dataring) * priv->num_rings, > + GFP_KERNEL); Coding style: please align the second line to the first parameter of kzalloc(). > + if (!priv->rings) { > + kfree(priv); > + return -ENOMEM; > + } > + > + for (i = 0; i < priv->num_rings; i++) { > + priv->rings[i].priv = priv; > + ret = xen_9pfs_front_alloc_dataring(dev, &priv->rings[i]); > + if (ret < 0) > + goto error; > + } > + > + again: > + ret = xenbus_transaction_start(&xbt); > + if (ret) { > + xenbus_dev_fatal(dev, ret, "starting transaction"); > + goto error; > + } > + ret = xenbus_printf(xbt, dev->nodename, "version", "%u", 1); > + if (ret) > + goto error_xenbus; > + ret = xenbus_printf(xbt, dev->nodename, "num-rings", "%u", priv->num_rings); > + if (ret) > + goto error_xenbus; > + for (i = 0; i < priv->num_rings; i++) { > + char str[16]; > + > + sprintf(str, "ring-ref%u", i); > + ret = xenbus_printf(xbt, dev->nodename, str, "%d", priv->rings[i].ref); > + if (ret) > + goto error_xenbus; > + > + sprintf(str, "event-channel-%u", i); This is dangerous: you are hard coding num_rings always being less than 10 here. Otherwise str[] isn't large enough. Mind adding BUILD_BUG_ON(XEN_9PFS_NUM_RINGS > 9)? > + ret = xenbus_printf(xbt, dev->nodename, str, "%u", priv->rings[i].evtchn); > + if (ret) > + goto error_xenbus; > + } > + priv->tag = xenbus_read(xbt, dev->nodename, "tag", NULL); > + if (ret) > + goto error_xenbus; > + ret = xenbus_transaction_end(xbt, 0); > + if (ret) { > + if (ret == -EAGAIN) > + goto again; > + xenbus_dev_fatal(dev, ret, "completing transaction"); > + goto error; > + } > + > + list_add_tail(&priv->list, &xen_9pfs_devs); Don't you need some kind of lock protecting the list? > + dev_set_drvdata(&dev->dev, priv); > + xenbus_switch_state(dev, XenbusStateInitialised); > + > return 0; > + > + error_xenbus: > + xenbus_transaction_end(xbt, 1); > + xenbus_dev_fatal(dev, ret, "writing xenstore"); > + error: > + dev_set_drvdata(&dev->dev, NULL); > + xen_9pfs_front_free(priv); > + return ret; > } > > static int xen_9pfs_front_resume(struct xenbus_device *dev) > { > + dev_warn(&dev->dev, "suspsend/resume unsupported\n"); > return 0; > } > > static void xen_9pfs_front_changed(struct xenbus_device *dev, > enum xenbus_state backend_state) > { > + switch (backend_state) { > + case XenbusStateReconfiguring: > + case XenbusStateReconfigured: > + case XenbusStateInitialising: > + case XenbusStateInitialised: > + case XenbusStateUnknown: > + break; > + > + case XenbusStateInitWait: > + break; > + > + case XenbusStateConnected: > + xenbus_switch_state(dev, XenbusStateConnected); > + break; > + > + case XenbusStateClosed: > + if (dev->state == XenbusStateClosed) > + break; > + /* Missed the backend's CLOSING state -- fallthrough */ > + case XenbusStateClosing: > + xenbus_frontend_closed(dev); > + break; > + } > } > > static struct xenbus_driver xen_9pfs_front_driver = { > Juergen