Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933358AbdCHAV0 (ORCPT ); Tue, 7 Mar 2017 19:21:26 -0500 Received: from mail.kernel.org ([198.145.29.136]:35094 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933274AbdCHAVT (ORCPT ); Tue, 7 Mar 2017 19:21:19 -0500 Date: Tue, 7 Mar 2017 16:11:19 -0800 (PST) From: Stefano Stabellini X-X-Sender: sstabellini@sstabellini-ThinkPad-X260 To: Boris Ostrovsky cc: Stefano Stabellini , xen-devel@lists.xenproject.org, linux-kernel@vger.kernel.org, Stefano Stabellini , jgross@suse.com, Eric Van Hensbergen , Ron Minnich , Latchesar Ionkov , v9fs-developer@lists.sourceforge.net Subject: Re: [PATCH 4/7] xen/9pfs: connect to the backend In-Reply-To: Message-ID: References: <1488830488-18506-1-git-send-email-sstabellini@kernel.org> <1488830488-18506-4-git-send-email-sstabellini@kernel.org> User-Agent: Alpine 2.10 (DEB 1266 2009-07-14) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 6272 Lines: 208 On Tue, 7 Mar 2017, Boris Ostrovsky wrote: > > +static int xen_9pfs_front_free(struct xen_9pfs_front_priv *priv) > > +{ > > + int i, j; > > + > > + list_del(&priv->list); > > + > > + for (i = 0; i < priv->num_rings; i++) { > > + if (priv->rings[i].intf == NULL) > > + break; > > Are we guaranteed that all subsequent entries are not allocated (i.e. > this shouldn't be 'continue')? Yes, we are guaranteed that all subsequent entries are NULL because they are allocated in order until an error occurs. > > + if (priv->rings[i].irq > 0) > > + unbind_from_irqhandler(priv->rings[i].irq, priv->dev); > > + if (priv->rings[i].bytes != 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].bytes, XEN_9PFS_RING_ORDER); > > + } > > + 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; > > + int ret = -ENOMEM; > > + > > + 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_free_page(GFP_KERNEL | __GFP_ZERO); > > + if (!ring->intf) > > + goto error; > > + memset(ring->intf, 0, XEN_PAGE_SIZE); > > get_zeroed_page()? (especially given that __get_free_page() returns > PAGE_SIZE, not XEN_PAGE_SIZE) Yes, good point. > > + ring->bytes = (void*)__get_free_pages(GFP_KERNEL | __GFP_ZERO, XEN_9PFS_RING_ORDER); > > + if (ring->bytes == NULL) > > + goto error; > > + for (i = 0; i < (1 << XEN_9PFS_RING_ORDER); i++) > > + ring->intf->ref[i] = gnttab_grant_foreign_access(dev->otherend_id, pfn_to_gfn(virt_to_pfn((void*)ring->bytes) + i), 0); > > + ring->ref = gnttab_grant_foreign_access(dev->otherend_id, pfn_to_gfn(virt_to_pfn((void*)ring->intf)), 0); > > + ring->ring.in = ring->bytes; > > + ring->ring.out = ring->bytes + XEN_9PFS_RING_SIZE; > > + > > + ret = xenbus_alloc_evtchn(dev, &ring->evtchn); > > + if (ret) > > + goto error; > > + ring->irq = bind_evtchn_to_irqhandler(ring->evtchn, xen_9pfs_front_event_handler, > > + 0, "xen_9pfs-frontend", ring); > > + if (ring->irq < 0) { > > + xenbus_free_evtchn(dev, ring->evtchn); > > + ret = ring->irq; > > + goto error; > > + } > > return 0; > > + > > +error: > > You may need to gnttab_end_foreign_access(). Actually this error path is unnecessary because it will be handled by xen_9pfs_front_probe, that calls xen_9pfs_front_free on errors. I'll remove it. > > + if (ring->intf != NULL) > > + kfree(ring->intf); > > + if (ring->bytes != NULL) > > + kfree(ring->bytes); > > + return ret; > > } > > > > static int xen_9pfs_front_probe(struct xenbus_device *dev, > > const struct xenbus_device_id *id) > > { > > + int ret = -EFAULT, i; > > Unnecessary initialization. I'll remove it. > > + 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")) > > + return -EINVAL; > > + kfree(versions); > > + ret = xenbus_scanf(XBT_NIL, dev->otherend, "max-rings", "%u", &max_rings); > > + 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); > > + if (ret < 0|| max_ring_order < XEN_9PFS_RING_ORDER) > > + 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); > > + if (!priv->rings) { > > + kfree(priv); > > + return -ENOMEM; > > + } > > + > > + 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]; > > + > > + priv->rings[i].priv = priv; > > + ret = xen_9pfs_front_alloc_dataring(dev, &priv->rings[i]); > > Not for -EAGAIN, I think. I don't think xen_9pfs_front_alloc_dataring can return EAGAIN. EAGAIN can only come from xenbus_transaction_end, the case we handle below. > > + if (ret < 0) > > + goto error_xenbus; > > + > > + 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); > > + 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); > > + 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; > > } > > >