Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754146AbdFNA6B (ORCPT ); Tue, 13 Jun 2017 20:58:01 -0400 Received: from mail.kernel.org ([198.145.29.99]:33582 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753382AbdFNA6A (ORCPT ); Tue, 13 Jun 2017 20:58:00 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 3427D22CB7 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: Tue, 13 Jun 2017 17:57:58 -0700 (PDT) From: Stefano Stabellini X-X-Sender: sstabellini@sstabellini-ThinkPad-X260 To: Juergen Gross cc: Stefano Stabellini , xen-devel@lists.xen.org, linux-kernel@vger.kernel.org, boris.ostrovsky@oracle.com, Stefano Stabellini Subject: Re: [PATCH v3 16/18] xen/pvcalls: implement read In-Reply-To: <99664d75-df13-2e25-a992-0b8050776d49@suse.com> Message-ID: References: <1496431915-20774-1-git-send-email-sstabellini@kernel.org> <1496431915-20774-16-git-send-email-sstabellini@kernel.org> <99664d75-df13-2e25-a992-0b8050776d49@suse.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 Content-Length: 4210 Lines: 129 On Tue, 13 Jun 2017, Juergen Gross wrote: > On 02/06/17 21:31, Stefano Stabellini wrote: > > When an active socket has data available, increment the io and read > > counters, and schedule the ioworker. > > > > Implement the read function by reading from the socket, writing the data > > to the data ring. > > > > Set in_error on error. > > > > Signed-off-by: Stefano Stabellini > > CC: boris.ostrovsky@oracle.com > > CC: jgross@suse.com > > --- > > drivers/xen/pvcalls-back.c | 85 ++++++++++++++++++++++++++++++++++++++++++++++ > > 1 file changed, 85 insertions(+) > > > > diff --git a/drivers/xen/pvcalls-back.c b/drivers/xen/pvcalls-back.c > > index 0283d49..e7d2b85 100644 > > --- a/drivers/xen/pvcalls-back.c > > +++ b/drivers/xen/pvcalls-back.c > > @@ -101,6 +101,81 @@ static int pvcalls_back_release_active(struct xenbus_device *dev, > > > > static void pvcalls_conn_back_read(unsigned long opaque) > > { > > + struct sock_mapping *map = (struct sock_mapping *)opaque; > > + struct msghdr msg; > > + struct kvec vec[2]; > > + RING_IDX cons, prod, size, wanted, array_size, masked_prod, masked_cons; > > + int32_t error; > > + struct pvcalls_data_intf *intf = map->ring; > > + struct pvcalls_data *data = &map->data; > > + unsigned long flags; > > + int ret; > > + > > + array_size = XEN_FLEX_RING_SIZE(map->ring_order); > > + cons = intf->in_cons; > > + prod = intf->in_prod; > > + error = intf->in_error; > > + /* read the indexes first, then deal with the data */ > > + virt_mb(); > > + > > + if (error) > > + return; > > + > > + size = pvcalls_queued(prod, cons, array_size); > > + if (size >= array_size) > > + return; > > + spin_lock_irqsave(&map->sock->sk->sk_receive_queue.lock, flags); > > + if (skb_queue_empty(&map->sock->sk->sk_receive_queue)) { > > + atomic_set(&map->read, 0); > > + spin_unlock_irqrestore(&map->sock->sk->sk_receive_queue.lock, > > + flags); > > + return; > > + } > > + spin_unlock_irqrestore(&map->sock->sk->sk_receive_queue.lock, flags); > > + wanted = array_size - size; > > + masked_prod = pvcalls_mask(prod, array_size); > > + masked_cons = pvcalls_mask(cons, array_size); > > + > > + memset(&msg, 0, sizeof(msg)); > > + msg.msg_iter.type = ITER_KVEC|WRITE; > > + msg.msg_iter.count = wanted; > > + if (masked_prod < masked_cons) { > > + vec[0].iov_base = data->in + masked_prod; > > + vec[0].iov_len = wanted; > > + msg.msg_iter.kvec = vec; > > + msg.msg_iter.nr_segs = 1; > > + } else { > > + vec[0].iov_base = data->in + masked_prod; > > + vec[0].iov_len = array_size - masked_prod; > > + vec[1].iov_base = data->in; > > + vec[1].iov_len = wanted - vec[0].iov_len; > > + msg.msg_iter.kvec = vec; > > + msg.msg_iter.nr_segs = 2; > > + } > > + > > + atomic_set(&map->read, 0); > > + ret = inet_recvmsg(map->sock, &msg, wanted, MSG_DONTWAIT); > > + WARN_ON(ret > 0 && ret > wanted); > > wanted is always > 0, so you can omit the ret > 0 test. Good point > > > + if (ret == -EAGAIN) /* shouldn't happen */ > > + return; > > + if (!ret) > > + ret = -ENOTCONN; > > + spin_lock_irqsave(&map->sock->sk->sk_receive_queue.lock, flags); > > + if (ret > 0 && !skb_queue_empty(&map->sock->sk->sk_receive_queue)) > > + atomic_inc(&map->read); > > + spin_unlock_irqrestore(&map->sock->sk->sk_receive_queue.lock, flags); > > + > > + /* write the data, then modify the indexes */ > > + virt_wmb(); > > + if (ret < 0) > > + intf->in_error = ret; > > + else > > + intf->in_prod = prod + ret; > > + /* update the indexes, then notify the other end */ > > + virt_wmb(); > > + notify_remote_via_irq(map->irq); > > + > > + return; > > } > > > > static int pvcalls_conn_back_write(struct sock_mapping *map) > > @@ -173,6 +248,16 @@ static void pvcalls_sk_state_change(struct sock *sock) > > > > static void pvcalls_sk_data_ready(struct sock *sock) > > { > > + struct sock_mapping *map = sock->sk_user_data; > > + struct pvcalls_ioworker *iow; > > + > > + if (map == NULL) > > + return; > > + > > + iow = &map->ioworker; > > + atomic_inc(&map->read); > > + atomic_inc(&map->io); > > + queue_work_on(iow->cpu, iow->wq, &iow->register_work); > > } > > > > static struct sock_mapping *pvcalls_new_active_socket( > > >