Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752290AbdHMBN7 (ORCPT ); Sat, 12 Aug 2017 21:13:59 -0400 Received: from userp1040.oracle.com ([156.151.31.81]:33953 "EHLO userp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752196AbdHMBN6 (ORCPT ); Sat, 12 Aug 2017 21:13:58 -0400 Subject: Re: [PATCH v3 05/13] xen/pvcalls: implement connect command To: Stefano Stabellini , xen-devel@lists.xen.org Cc: linux-kernel@vger.kernel.org, jgross@suse.com, Stefano Stabellini References: <1501541855-7354-1-git-send-email-sstabellini@kernel.org> <1501541855-7354-5-git-send-email-sstabellini@kernel.org> From: Boris Ostrovsky Message-ID: <98a37ce0-468c-0938-a56d-31bbde177c91@oracle.com> Date: Sat, 12 Aug 2017 21:12:45 -0400 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: <1501541855-7354-5-git-send-email-sstabellini@kernel.org> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Source-IP: userv0021.oracle.com [156.151.31.71] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 7001 Lines: 243 On 07/31/2017 06:57 PM, Stefano Stabellini wrote: > Send PVCALLS_CONNECT to the backend. Allocate a new ring and evtchn for > the active socket. > > Introduce fields in struct sock_mapping to keep track of active 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. > > Signed-off-by: Stefano Stabellini > CC: boris.ostrovsky@oracle.com > CC: jgross@suse.com > --- > drivers/xen/pvcalls-front.c | 146 ++++++++++++++++++++++++++++++++++++++++++++ > drivers/xen/pvcalls-front.h | 2 + > 2 files changed, 148 insertions(+) > > diff --git a/drivers/xen/pvcalls-front.c b/drivers/xen/pvcalls-front.c > index 7c4a7cb..379b8fb 100644 > --- a/drivers/xen/pvcalls-front.c > +++ b/drivers/xen/pvcalls-front.c > @@ -13,6 +13,10 @@ > */ > > #include > +#include > +#include > + > +#include > > #include > #include > @@ -44,6 +48,18 @@ 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 inline int get_request(struct pvcalls_bedata *bedata, int *req_id) > @@ -97,6 +113,18 @@ 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; > @@ -162,6 +190,124 @@ int pvcalls_front_socket(struct socket *sock) > return ret; > } > > +static int create_active(struct sock_mapping *map, int *evtchn) > +{ > + void *bytes; > + int ret = -ENOMEM, irq = -1, i; > + > + 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); Not needed (page allocated with __GFP_ZERO) BTW, are you operating on XEN_PAGE_SIZE of PAGE_SIZE? Because if it's the former than __get_free_page() may be way more than what you need. (below too) > + map->active.ring->ring_order = PVCALLS_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++) PVCALLS_RING_ORDER > + 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) { > + ret = irq; > + goto out_error; > + } > + > + map->active.irq = irq; > + map->active_socket = true; > + mutex_init(&map->active.in_mutex); > + mutex_init(&map->active.out_mutex); > + > + return 0; > + > +out_error: > + if (irq >= 0) > + unbind_from_irqhandler(irq, map); > + else if (*evtchn >= 0) *evtchn may have been passed in as >=0. You probably want to set to -1 or something in the beginning. > + xenbus_free_evtchn(pvcalls_front_dev, *evtchn); > + kfree(map->active.data.in); > + kfree(map->active.ring); > + kfree(map); Probably a matter of personal style but I think it's better to free map in the caller. Actually, should it be freed? The caller gets an error if get_request() or create_active() fail. In the first case map is not freed. Is the caller going to distinguish EAGAIN from any other error and know that map does not need to be allocated? (Also I think you need to unlink the map from socket_mapping list before freeing it). -boris > + return ret; > +} > + > +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); > + > + map = (struct sock_mapping *) READ_ONCE(sock->sk->sk_send_head); > + if (!map) > + return -EINVAL; > + > + spin_lock(&bedata->pvcallss_lock); > + ret = get_request(bedata, &req_id); > + if (ret < 0) { > + spin_unlock(&bedata->pvcallss_lock); > + return ret; > + } > + ret = create_active(map, &evtchn); > + if (ret < 0) { > + spin_unlock(&bedata->pvcallss_lock); > + return ret; > + } > + > + req = RING_GET_REQUEST(&bedata->ring, req_id); > + req->req_id = req_id; > + req->cmd = PVCALLS_CONNECT; > + req->u.connect.id = (uint64_t)map; > + 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; > + > + map->sock = sock; > + > + 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" }, > { "" } > 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 >