Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751413AbdGZRvo (ORCPT ); Wed, 26 Jul 2017 13:51:44 -0400 Received: from aserp1040.oracle.com ([141.146.126.69]:25908 "EHLO aserp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750918AbdGZRvn (ORCPT ); Wed, 26 Jul 2017 13:51:43 -0400 Subject: Re: [PATCH v2 07/13] xen/pvcalls: implement accept command To: Stefano Stabellini , xen-devel@lists.xen.org References: <1501017730-12797-1-git-send-email-sstabellini@kernel.org> <1501017730-12797-7-git-send-email-sstabellini@kernel.org> Cc: linux-kernel@vger.kernel.org, jgross@suse.com, Stefano Stabellini From: Boris Ostrovsky Message-ID: Date: Wed, 26 Jul 2017 13:52:26 -0400 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.8.0 MIME-Version: 1.0 In-Reply-To: <1501017730-12797-7-git-send-email-sstabellini@kernel.org> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit X-Source-IP: aserv0022.oracle.com [141.146.126.234] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4217 Lines: 128 On 07/25/2017 05:22 PM, Stefano Stabellini wrote: > Send PVCALLS_ACCEPT to the backend. Allocate a new active socket. Make > sure that only one accept command is executed at any given time by > setting PVCALLS_FLAG_ACCEPT_INFLIGHT and waiting on the > inflight_accept_req waitqueue. > > 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. > > Convert the new 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 | 79 +++++++++++++++++++++++++++++++++++++++++++++ > drivers/xen/pvcalls-front.h | 3 ++ > 2 files changed, 82 insertions(+) > > diff --git a/drivers/xen/pvcalls-front.c b/drivers/xen/pvcalls-front.c > index 3b5d50e..b8c4538 100644 > --- a/drivers/xen/pvcalls-front.c > +++ b/drivers/xen/pvcalls-front.c > @@ -413,6 +413,85 @@ int pvcalls_front_listen(struct socket *sock, int backlog) > return ret; > } > > +int pvcalls_front_accept(struct socket *sock, struct socket *newsock, int flags) > +{ > + struct pvcalls_bedata *bedata; > + struct sock_mapping *map; > + struct sock_mapping *map2 = NULL; > + struct xen_pvcalls_request *req; > + int notify, req_id, ret, evtchn; > + > + if (!pvcalls_front_dev) > + return -ENOTCONN; > + bedata = dev_get_drvdata(&pvcalls_front_dev->dev); > + > + map = (struct sock_mapping *) READ_ONCE(sock->sk->sk_send_head); > + if (!map) > + return -ENOTSOCK; > + > + if (map->passive.status != PVCALLS_STATUS_LISTEN) > + return -EINVAL; > + > + /* > + * Backend only supports 1 inflight accept request, will return > + * errors for the others > + */ > + if (test_and_set_bit(PVCALLS_FLAG_ACCEPT_INFLIGHT, > + (void *)&map->passive.flags)) { > + if (wait_event_interruptible(map->passive.inflight_accept_req, > + !test_and_set_bit(PVCALLS_FLAG_ACCEPT_INFLIGHT, > + (void *)&map->passive.flags)) > + != 0) Unnecessary "!=0". -boris > + return -EINTR; > + } > + > + > + newsock->sk = kzalloc(sizeof(*newsock->sk), GFP_KERNEL); > + if (newsock->sk == NULL) > + return -ENOMEM; > + > + 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) { > + kfree(newsock->sk); > + spin_unlock(&bedata->pvcallss_lock); > + return -EAGAIN; > + } > + > + map2 = create_active(&evtchn); > + > + req = RING_GET_REQUEST(&bedata->ring, req_id); > + req->req_id = req_id; > + req->cmd = PVCALLS_ACCEPT; > + req->u.accept.id = (uint64_t) sock; > + req->u.accept.ref = map2->active.ref; > + req->u.accept.id_new = (uint64_t) newsock; > + req->u.accept.evtchn = evtchn; > + > + list_add_tail(&map2->list, &bedata->socket_mappings); > + WRITE_ONCE(newsock->sk->sk_send_head, (void *)map2); > + map2->sock = newsock; > + > + 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); > + > + clear_bit(PVCALLS_FLAG_ACCEPT_INFLIGHT, (void *)&map->passive.flags); > + wake_up(&map->passive.inflight_accept_req); > + > + 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 aa8fe10..ab4f1da 100644 > --- a/drivers/xen/pvcalls-front.h > +++ b/drivers/xen/pvcalls-front.h > @@ -10,5 +10,8 @@ int pvcalls_front_bind(struct socket *sock, > struct sockaddr *addr, > int addr_len); > int pvcalls_front_listen(struct socket *sock, int backlog); > +int pvcalls_front_accept(struct socket *sock, > + struct socket *newsock, > + int flags); > > #endif