Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751852AbdGZOvd (ORCPT ); Wed, 26 Jul 2017 10:51:33 -0400 Received: from aserp1040.oracle.com ([141.146.126.69]:44784 "EHLO aserp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751672AbdGZOvc (ORCPT ); Wed, 26 Jul 2017 10:51:32 -0400 Subject: Re: [PATCH v2 04/13] xen/pvcalls: implement connect command To: Stefano Stabellini , xen-devel@lists.xen.org References: <1501017730-12797-1-git-send-email-sstabellini@kernel.org> <1501017730-12797-4-git-send-email-sstabellini@kernel.org> Cc: linux-kernel@vger.kernel.org, jgross@suse.com, Stefano Stabellini From: Boris Ostrovsky Organization: Oracle Corporation Message-ID: <5978AC68.7050403@oracle.com> Date: Wed, 26 Jul 2017 10:51:20 -0400 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:38.0) Gecko/20100101 Thunderbird/38.8.0 MIME-Version: 1.0 In-Reply-To: <1501017730-12797-4-git-send-email-sstabellini@kernel.org> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit X-Source-IP: aserv0021.oracle.com [141.146.126.233] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 9276 Lines: 297 On 7/25/2017 5:22 PM, Stefano Stabellini wrote: > Send PVCALLS_CONNECT to the backend. Allocate a new ring and evtchn for > the active socket. > > Introduce a data structure to keep track of sockets. Introduce a > waitqueue to allow the frontend to wait on data coming from the backend > on the active socket (recvmsg command). > > Two mutexes (one of reads and one for writes) will be used to protect > the active socket in and out rings from concurrent accesses. > > sock->sk->sk_send_head is not used for ip sockets: reuse the field to > store a pointer to the struct sock_mapping corresponding to the socket. > This way, we can easily get the struct sock_mapping from the struct > socket. This needs to be documented in the code, not (just) in commit message. > > Convert the struct socket pointer into an uint64_t and use it as id for > the new socket to pass to the backend. > > Signed-off-by: Stefano Stabellini > CC: boris.ostrovsky@oracle.com > CC: jgross@suse.com > --- > drivers/xen/pvcalls-front.c | 177 +++++++++++++++++++++++++++++++++++++++++--- > drivers/xen/pvcalls-front.h | 2 + > 2 files changed, 168 insertions(+), 11 deletions(-) > > diff --git a/drivers/xen/pvcalls-front.c b/drivers/xen/pvcalls-front.c > index d1dbcf1..d0f5f42 100644 > --- a/drivers/xen/pvcalls-front.c > +++ b/drivers/xen/pvcalls-front.c > @@ -13,6 +13,10 @@ > */ > > #include > +#include > +#include > + > +#include > > #include > #include > @@ -40,6 +44,24 @@ struct pvcalls_bedata { > }; > struct xenbus_device *pvcalls_front_dev; > > +struct sock_mapping { > + bool active_socket; > + struct list_head list; > + struct socket *sock; > + union { > + struct { > + int irq; > + grant_ref_t ref; > + struct pvcalls_data_intf *ring; > + struct pvcalls_data data; > + struct mutex in_mutex; > + struct mutex out_mutex; > + > + wait_queue_head_t inflight_conn_req; > + } active; > + }; > +}; > + > static irqreturn_t pvcalls_front_event_handler(int irq, void *dev_id) > { > struct xenbus_device *dev = dev_id; > @@ -84,6 +106,18 @@ static irqreturn_t pvcalls_front_event_handler(int irq, void *dev_id) > return IRQ_HANDLED; > } > > +static irqreturn_t pvcalls_front_conn_handler(int irq, void *sock_map) > +{ > + struct sock_mapping *map = sock_map; > + > + if (map == NULL) > + return IRQ_HANDLED; > + > + wake_up_interruptible(&map->active.inflight_conn_req); > + > + return IRQ_HANDLED; > +} > + > int pvcalls_front_socket(struct socket *sock) > { > struct pvcalls_bedata *bedata; > @@ -137,6 +171,127 @@ int pvcalls_front_socket(struct socket *sock) > return ret; > } > > +static struct sock_mapping *create_active(int *evtchn) > +{ > + struct sock_mapping *map = NULL; > + void *bytes; > + int ret, irq = -1, i; > + > + map = kzalloc(sizeof(*map), GFP_KERNEL); > + if (map == NULL) > + return NULL; > + > + init_waitqueue_head(&map->active.inflight_conn_req); > + > + map->active.ring = (struct pvcalls_data_intf *) > + __get_free_page(GFP_KERNEL | __GFP_ZERO); > + if (map->active.ring == NULL) > + goto out_error; > + memset(map->active.ring, 0, XEN_PAGE_SIZE); > + map->active.ring->ring_order = RING_ORDER; > + bytes = (void *)__get_free_pages(GFP_KERNEL | __GFP_ZERO, > + map->active.ring->ring_order); > + if (bytes == NULL) > + goto out_error; > + for (i = 0; i < (1 << map->active.ring->ring_order); i++) > + map->active.ring->ref[i] = gnttab_grant_foreign_access( > + pvcalls_front_dev->otherend_id, > + pfn_to_gfn(virt_to_pfn(bytes) + i), 0); > + > + map->active.ref = gnttab_grant_foreign_access( > + pvcalls_front_dev->otherend_id, > + pfn_to_gfn(virt_to_pfn((void *)map->active.ring)), 0); > + > + map->active.data.in = bytes; > + map->active.data.out = bytes + > + XEN_FLEX_RING_SIZE(map->active.ring->ring_order); > + > + ret = xenbus_alloc_evtchn(pvcalls_front_dev, evtchn); > + if (ret) > + goto out_error; > + irq = bind_evtchn_to_irqhandler(*evtchn, pvcalls_front_conn_handler, > + 0, "pvcalls-frontend", map); > + if (irq < 0) > + goto out_error; > + > + map->active.irq = irq; > + map->active_socket = true; > + mutex_init(&map->active.in_mutex); > + mutex_init(&map->active.out_mutex); > + > + return map; > + > +out_error: > + if (irq >= 0) > + unbind_from_irqhandler(irq, map); > + else if (*evtchn >= 0) > + xenbus_free_evtchn(pvcalls_front_dev, *evtchn); > + kfree(map->active.data.in); > + kfree(map->active.ring); > + kfree(map); > + return NULL; > +} > + > +int pvcalls_front_connect(struct socket *sock, struct sockaddr *addr, > + int addr_len, int flags) > +{ > + struct pvcalls_bedata *bedata; > + struct sock_mapping *map = NULL; > + struct xen_pvcalls_request *req; > + int notify, req_id, ret, evtchn; > + > + if (!pvcalls_front_dev) > + return -ENETUNREACH; > + if (addr->sa_family != AF_INET || sock->type != SOCK_STREAM) > + return -ENOTSUPP; > + > + bedata = dev_get_drvdata(&pvcalls_front_dev->dev); > + > + spin_lock(&bedata->pvcallss_lock); > + req_id = bedata->ring.req_prod_pvt & (RING_SIZE(&bedata->ring) - 1); > + if (RING_FULL(&bedata->ring) || > + READ_ONCE(bedata->rsp[req_id].req_id) != PVCALLS_INVALID_ID) { > + spin_unlock(&bedata->pvcallss_lock); > + return -EAGAIN; > + } > + > + map = create_active(&evtchn); > + if (!map) { > + spin_unlock(&bedata->pvcallss_lock); > + return -ENOMEM; > + } > + > + req = RING_GET_REQUEST(&bedata->ring, req_id); > + req->req_id = req_id; > + req->cmd = PVCALLS_CONNECT; > + req->u.connect.id = (uint64_t)sock; > + memcpy(req->u.connect.addr, addr, sizeof(*addr)); > + req->u.connect.len = addr_len; > + req->u.connect.flags = flags; > + req->u.connect.ref = map->active.ref; > + req->u.connect.evtchn = evtchn; > + > + list_add_tail(&map->list, &bedata->socket_mappings); > + map->sock = sock; > + WRITE_ONCE(sock->sk->sk_send_head, (void *)map); > + > + bedata->ring.req_prod_pvt++; > + RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&bedata->ring, notify); > + spin_unlock(&bedata->pvcallss_lock); > + > + if (notify) > + notify_remote_via_irq(bedata->irq); > + > + wait_event(bedata->inflight_req, > + READ_ONCE(bedata->rsp[req_id].req_id) == req_id); > + > + ret = bedata->rsp[req_id].ret; > + /* read ret, then set this rsp slot to be reused */ > + smp_mb(); > + WRITE_ONCE(bedata->rsp[req_id].req_id, PVCALLS_INVALID_ID); > + return ret; > +} > + > static const struct xenbus_device_id pvcalls_front_ids[] = { > { "pvcalls" }, > { "" } > @@ -150,7 +305,7 @@ static int pvcalls_front_remove(struct xenbus_device *dev) > static int pvcalls_front_probe(struct xenbus_device *dev, > const struct xenbus_device_id *id) > { > - int ret = -EFAULT, evtchn, ref = -1, i; > + int ret = -ENOMEM, evtchn, ref = -1, i; > unsigned int max_page_order, function_calls, len; > char *versions; > grant_ref_t gref_head = 0; > @@ -171,15 +326,13 @@ static int pvcalls_front_probe(struct xenbus_device *dev, > return -EINVAL; > } > kfree(versions); > - ret = xenbus_scanf(XBT_NIL, dev->otherend, > - "max-page-order", "%u", &max_page_order); > - if (ret <= 0) > - return -ENODEV; > + max_page_order = xenbus_read_unsigned(dev->otherend, > + "max-page-order", 0); > if (max_page_order < RING_ORDER) > return -ENODEV; > - ret = xenbus_scanf(XBT_NIL, dev->otherend, > - "function-calls", "%u", &function_calls); > - if (ret <= 0 || function_calls != 1) > + function_calls = xenbus_read_unsigned(dev->otherend, > + "function-calls", 0); > + if (function_calls != 1) > return -ENODEV; > pr_info("%s max-page-order is %u\n", __func__, max_page_order); > > @@ -187,6 +340,8 @@ static int pvcalls_front_probe(struct xenbus_device *dev, > if (!bedata) > return -ENOMEM; > > + dev_set_drvdata(&dev->dev, bedata); > + pvcalls_front_dev = dev; > init_waitqueue_head(&bedata->inflight_req); > for (i = 0; i < PVCALLS_NR_REQ_PER_RING; i++) > bedata->rsp[i].req_id = PVCALLS_INVALID_ID; > @@ -214,8 +369,10 @@ static int pvcalls_front_probe(struct xenbus_device *dev, > if (ret < 0) > goto error; > bedata->ref = ref = gnttab_claim_grant_reference(&gref_head); > - if (ref < 0) > + if (ref < 0) { > + ret = ref; > goto error; > + } > gnttab_grant_foreign_access_ref(ref, dev->otherend_id, > virt_to_gfn((void *)sring), 0); > > @@ -246,8 +403,6 @@ static int pvcalls_front_probe(struct xenbus_device *dev, > INIT_LIST_HEAD(&bedata->socket_mappings); > INIT_LIST_HEAD(&bedata->socketpass_mappings); > spin_lock_init(&bedata->pvcallss_lock); > - dev_set_drvdata(&dev->dev, bedata); > - pvcalls_front_dev = dev; > xenbus_switch_state(dev, XenbusStateInitialised); Why are these changes made here and not in the original patch? -boris > > return 0; > diff --git a/drivers/xen/pvcalls-front.h b/drivers/xen/pvcalls-front.h > index b7dabed..63b0417 100644 > --- a/drivers/xen/pvcalls-front.h > +++ b/drivers/xen/pvcalls-front.h > @@ -4,5 +4,7 @@ > #include > > int pvcalls_front_socket(struct socket *sock); > +int pvcalls_front_connect(struct socket *sock, struct sockaddr *addr, > + int addr_len, int flags); > > #endif