From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757218AbdIHVYA (ORCPT ); Fri, 8 Sep 2017 17:24:00 -0400 Received: from mail.kernel.org ([198.145.29.99]:59632 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757082AbdIHVX6 (ORCPT ); Fri, 8 Sep 2017 17:23:58 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org F239121D28 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=sstabellini@kernel.org Date: Fri, 8 Sep 2017 14:23:56 -0700 (PDT) From: Stefano Stabellini X-X-Sender: sstabellini@sstabellini-ThinkPad-X260 To: Boris Ostrovsky cc: Stefano Stabellini , xen-devel@lists.xen.org, linux-kernel@vger.kernel.org, jgross@suse.com, Stefano Stabellini Subject: Re: [PATCH v3 05/13] xen/pvcalls: implement connect command In-Reply-To: <98a37ce0-468c-0938-a56d-31bbde177c91@oracle.com> Message-ID: References: <1501541855-7354-1-git-send-email-sstabellini@kernel.org> <1501541855-7354-5-git-send-email-sstabellini@kernel.org> <98a37ce0-468c-0938-a56d-31bbde177c91@oracle.com> 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 On Sat, 12 Aug 2017, Boris Ostrovsky wrote: > 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) OK > 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) It is the former, but a 64K kernel is not able to allocate a 4K page, so we'll have to accept the memory waste. > > + 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 OK > > + 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. OK > > + 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? You are right, map shouldn't be freed, as "close" is still supposed to be called afterwards, even if "connect" failed. > (Also I think you need to unlink the map from socket_mapping list before > freeing it). As map shouldn't be freed, it should also not be removed by socket_mapping. > > + 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 > > >