Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751633AbdGZXWQ (ORCPT ); Wed, 26 Jul 2017 19:22:16 -0400 Received: from aserp1040.oracle.com ([141.146.126.69]:42153 "EHLO aserp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751576AbdGZXWN (ORCPT ); Wed, 26 Jul 2017 19:22:13 -0400 Subject: Re: [PATCH v2 10/13] xen/pvcalls: implement poll command To: Stefano Stabellini , xen-devel@lists.xen.org References: <1501017730-12797-1-git-send-email-sstabellini@kernel.org> <1501017730-12797-10-git-send-email-sstabellini@kernel.org> Cc: linux-kernel@vger.kernel.org, jgross@suse.com, Stefano Stabellini From: Boris Ostrovsky Message-ID: <018b3547-f0b8-8b1b-84b2-525fefafdace@oracle.com> Date: Wed, 26 Jul 2017 19:23:39 -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: <1501017730-12797-10-git-send-email-sstabellini@kernel.org> Content-Type: text/plain; charset=windows-1252 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: 6582 Lines: 198 On 07/25/2017 05:22 PM, Stefano Stabellini wrote: > For active sockets, check the indexes and use the inflight_conn_req > waitqueue to wait. > > For passive sockets, send PVCALLS_POLL to the backend. Use the > inflight_accept_req waitqueue if an accept is outstanding. Otherwise use > the inflight_req waitqueue: inflight_req is awaken when a new response > is received; on wakeup we check whether the POLL response is arrived by > looking at the PVCALLS_FLAG_POLL_RET flag. We set the flag from > pvcalls_front_event_handler, if the response was for a POLL command. > > In pvcalls_front_event_handler, get the struct socket pointer from the > poll id (we previously converted struct socket* to uint64_t and used it > as id). > > Signed-off-by: Stefano Stabellini > CC: boris.ostrovsky@oracle.com > CC: jgross@suse.com > --- > drivers/xen/pvcalls-front.c | 134 ++++++++++++++++++++++++++++++++++++++++---- > drivers/xen/pvcalls-front.h | 3 + > 2 files changed, 126 insertions(+), 11 deletions(-) > > diff --git a/drivers/xen/pvcalls-front.c b/drivers/xen/pvcalls-front.c > index b4ca569..833b717 100644 > --- a/drivers/xen/pvcalls-front.c > +++ b/drivers/xen/pvcalls-front.c > @@ -130,17 +130,35 @@ static irqreturn_t pvcalls_front_event_handler(int irq, void *dev_id) > rsp = RING_GET_RESPONSE(&bedata->ring, bedata->ring.rsp_cons); > > req_id = rsp->req_id; > - src = (uint8_t *)&bedata->rsp[req_id]; > - src += sizeof(rsp->req_id); > - dst = (uint8_t *)rsp; > - dst += sizeof(rsp->req_id); > - memcpy(dst, src, sizeof(*rsp) - sizeof(rsp->req_id)); > - /* > - * First copy the rest of the data, then req_id. It is > - * paired with the barrier when accessing bedata->rsp. > - */ > - smp_wmb(); > - WRITE_ONCE(bedata->rsp[req_id].req_id, rsp->req_id); > + if (rsp->cmd == PVCALLS_POLL) { > + struct socket *sock = (struct socket *) rsp->u.poll.id; > + struct sock_mapping *map = > + (struct sock_mapping *) > + READ_ONCE(sock->sk->sk_send_head); > + > + set_bit(PVCALLS_FLAG_POLL_RET, > + (void *)&map->passive.flags); > + /* > + * Set RET, then clear INFLIGHT. It pairs with > + * the checks at the beginning of > + * pvcalls_front_poll_passive. > + */ > + smp_wmb(); virt_wmb() (here, below, and I think I saw it somewhere else) > + clear_bit(PVCALLS_FLAG_POLL_INFLIGHT, > + (void *)&map->passive.flags); > + } else { > + src = (uint8_t *)&bedata->rsp[req_id]; > + src += sizeof(rsp->req_id); > + dst = (uint8_t *)rsp; > + dst += sizeof(rsp->req_id); > + memcpy(dst, src, sizeof(*rsp) - sizeof(rsp->req_id)); > + /* > + * First copy the rest of the data, then req_id. It is > + * paired with the barrier when accessing bedata->rsp. > + */ > + smp_wmb(); > + WRITE_ONCE(bedata->rsp[req_id].req_id, rsp->req_id); > + } > > done = 1; > bedata->ring.rsp_cons++; > @@ -707,6 +725,100 @@ int pvcalls_front_accept(struct socket *sock, struct socket *newsock, int flags) > return ret; > } > > +static unsigned int pvcalls_front_poll_passive(struct file *file, > + struct pvcalls_bedata *bedata, > + struct sock_mapping *map, > + poll_table *wait) > +{ > + int notify, req_id; > + struct xen_pvcalls_request *req; > + > + if (test_bit(PVCALLS_FLAG_ACCEPT_INFLIGHT, > + (void *)&map->passive.flags)) { > + poll_wait(file, &map->passive.inflight_accept_req, wait); > + return 0; > + } > + > + if (test_and_clear_bit(PVCALLS_FLAG_POLL_RET, > + (void *)&map->passive.flags)) > + return POLLIN; > + > + /* > + * First check RET, then INFLIGHT. No barriers necessary to > + * ensure execution ordering because of the conditional > + * instructions creating control dependencies. > + */ > + > + if (test_and_set_bit(PVCALLS_FLAG_POLL_INFLIGHT, > + (void *)&map->passive.flags)) { > + poll_wait(file, &bedata->inflight_req, wait); > + return 0; > + } > + > + 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; > + } > + req = RING_GET_REQUEST(&bedata->ring, req_id); > + req->req_id = req_id; > + req->cmd = PVCALLS_POLL; > + req->u.poll.id = (uint64_t) map->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); > + > + poll_wait(file, &bedata->inflight_req, wait); > + return 0; > +} > + > +static unsigned int pvcalls_front_poll_active(struct file *file, > + struct pvcalls_bedata *bedata, > + struct sock_mapping *map, > + poll_table *wait) > +{ > + unsigned int mask = 0; > + int32_t in_error, out_error; > + struct pvcalls_data_intf *intf = map->active.ring; > + > + out_error = intf->out_error; > + in_error = intf->in_error; > + > + poll_wait(file, &map->active.inflight_conn_req, wait); > + if (pvcalls_front_write_todo(map)) > + mask |= POLLOUT | POLLWRNORM; > + if (pvcalls_front_read_todo(map)) > + mask |= POLLIN | POLLRDNORM; > + if (in_error != 0 || out_error != 0) > + mask |= POLLERR; > + > + return mask; > +} > + > +unsigned int pvcalls_front_poll(struct file *file, struct socket *sock, > + poll_table *wait) > +{ > + struct pvcalls_bedata *bedata; > + struct sock_mapping *map; > + > + if (!pvcalls_front_dev) > + return POLLNVAL; > + bedata = dev_get_drvdata(&pvcalls_front_dev->dev); > + > + map = (struct sock_mapping *) READ_ONCE(sock->sk->sk_send_head); > + if (!map) > + return POLLNVAL; > + if (map->active_socket) > + return pvcalls_front_poll_active(file, bedata, map, wait); > + else > + return pvcalls_front_poll_passive(file, bedata, map, wait); > +} All other routines return an int (0 or error code). Shouldn't they all have the same return type? (In fact, where are all these routines called from?) -boris > + > 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 de24041..25e05b8 100644 > --- a/drivers/xen/pvcalls-front.h > +++ b/drivers/xen/pvcalls-front.h > @@ -20,5 +20,8 @@ int pvcalls_front_recvmsg(struct socket *sock, > struct msghdr *msg, > size_t len, > int flags); > +unsigned int pvcalls_front_poll(struct file *file, > + struct socket *sock, > + poll_table *wait); > > #endif