From patchwork Tue Jul 25 21:22:06 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Stefano Stabellini X-Patchwork-Id: 9863843 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id C1F1C6038C for ; Tue, 25 Jul 2017 21:24:58 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id A8A2328405 for ; Tue, 25 Jul 2017 21:24:58 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 99FD0286F3; Tue, 25 Jul 2017 21:24:58 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-4.2 required=2.0 tests=BAYES_00, RCVD_IN_DNSWL_MED autolearn=ham version=3.3.1 Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (using TLSv1.2 with cipher AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 21C3328405 for ; Tue, 25 Jul 2017 21:24:58 +0000 (UTC) Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.84_2) (envelope-from ) id 1da7I5-00052t-FZ; Tue, 25 Jul 2017 21:22:53 +0000 Received: from mail6.bemta6.messagelabs.com ([193.109.254.103]) by lists.xenproject.org with esmtp (Exim 4.84_2) (envelope-from ) id 1da7I4-00051K-Jh for xen-devel@lists.xen.org; Tue, 25 Jul 2017 21:22:52 +0000 Received: from [193.109.254.147] by server-7.bemta-6.messagelabs.com id CB/5E-03557-CA6B7795; Tue, 25 Jul 2017 21:22:52 +0000 X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFvrPLMWRWlGSWpSXmKPExsVybKJssu7qbeW RBvcbOS2WfFzM4sDocXT3b6YAxijWzLyk/IoE1ox986axFvxRrlh11bKBcYJcFyMXh5DAOiaJ aff3MXUxcnKwCDhI3Dq/Ecjm4GAUiJF48MMaJMwoECYx+fISVhCbTcBQ4u+TTWwgtoiAtMS1z 5cZQeYwC0xmlHj97hczSK+wgIXElD5eiJGqErO/fmIGsXkF3CTan60AsyUE5CROHpsMNpNTwF 1i/sztLBD3tDNKfNx6mnkCI+8CRoZVjBrFqUVlqUW6RoZ6SUWZ6RkluYmZObqGBmZ6uanFxYn pqTmJScV6yfm5mxiBwcAABDsY/ywLOMQoycGkJMr7Tbc8UogvKT+lMiOxOCO+qDQntfgQowwH h5IE76StQDnBotT01Iq0zBxgWMKkJTh4lER4e0HSvMUFibnFmekQqVOMxhwbVq//wsTxasL/b 0xCLHn5ealS4rwGIKUCIKUZpXlwg2DxcolRVkqYlxHoNCGegtSi3MwSVPlXjOIcjErCvFdApv Bk5pXA7XsFdAoT0ClzZpSCnFKSiJCSamBs2WQo6dtpqRfIcTPr98P79/3+hRzlmiF7vDaNvSh 8kfbbk1/WxMQ8dbDrv1MesFZI+tSuhxuL2iYmXtjWw9YXGLGEv9IyOJ4hu9pkpaeKW56oiNzR b6qujLUf3YNbOFsWzfKLVuJz374pTvdZPHPMrn6RW3lT8jf6aF94bH55yctK7p8sq5VYijMSD bWYi4oTAaAxQjySAgAA X-Env-Sender: sstabellini@kernel.org X-Msg-Ref: server-12.tower-27.messagelabs.com!1501017769!107388508!1 X-Originating-IP: [198.145.29.99] X-SpamReason: No, hits=0.0 required=7.0 tests= X-StarScan-Received: X-StarScan-Version: 9.4.25; banners=-,-,- X-VirusChecked: Checked Received: (qmail 53328 invoked from network); 25 Jul 2017 21:22:50 -0000 Received: from mail.kernel.org (HELO mail.kernel.org) (198.145.29.99) by server-12.tower-27.messagelabs.com with DHE-RSA-AES256-GCM-SHA384 encrypted SMTP; 25 Jul 2017 21:22:50 -0000 Received: from localhost.localdomain (162-198-228-33.lightspeed.wlfrct.sbcglobal.net [162.198.228.33]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 3531122C8F; Tue, 25 Jul 2017 21:22:19 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 3531122C8F From: Stefano Stabellini To: xen-devel@lists.xen.org Date: Tue, 25 Jul 2017 14:22:06 -0700 Message-Id: <1501017730-12797-9-git-send-email-sstabellini@kernel.org> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1501017730-12797-1-git-send-email-sstabellini@kernel.org> References: <1501017730-12797-1-git-send-email-sstabellini@kernel.org> Cc: jgross@suse.com, Stefano Stabellini , boris.ostrovsky@oracle.com, sstabellini@kernel.org, linux-kernel@vger.kernel.org Subject: [Xen-devel] [PATCH v2 09/13] xen/pvcalls: implement recvmsg X-BeenThere: xen-devel@lists.xen.org X-Mailman-Version: 2.1.18 Precedence: list List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Errors-To: xen-devel-bounces@lists.xen.org Sender: "Xen-devel" X-Virus-Scanned: ClamAV using ClamSMTP Implement recvmsg by copying data from the "in" ring. If not enough data is available and the recvmsg call is blocking, then wait on the inflight_conn_req waitqueue. Take the active socket in_mutex so that only one function can access the ring at any given time. If not enough data is available on the ring, rather than returning immediately or sleep-waiting, spin for up to 5000 cycles. This small optimization turns out to improve performance and latency significantly. Signed-off-by: Stefano Stabellini CC: boris.ostrovsky@oracle.com CC: jgross@suse.com --- drivers/xen/pvcalls-front.c | 106 ++++++++++++++++++++++++++++++++++++++++++++ drivers/xen/pvcalls-front.h | 4 ++ 2 files changed, 110 insertions(+) diff --git a/drivers/xen/pvcalls-front.c b/drivers/xen/pvcalls-front.c index d8ed280..b4ca569 100644 --- a/drivers/xen/pvcalls-front.c +++ b/drivers/xen/pvcalls-front.c @@ -96,6 +96,20 @@ static int pvcalls_front_write_todo(struct sock_mapping *map) return size - pvcalls_queued(prod, cons, size); } +static bool pvcalls_front_read_todo(struct sock_mapping *map) +{ + struct pvcalls_data_intf *intf = map->active.ring; + RING_IDX cons, prod; + int32_t error; + + cons = intf->in_cons; + prod = intf->in_prod; + error = intf->in_error; + return (error != 0 || + pvcalls_queued(prod, cons, + XEN_FLEX_RING_SIZE(intf->ring_order))) != 0; +} + static irqreturn_t pvcalls_front_event_handler(int irq, void *dev_id) { struct xenbus_device *dev = dev_id; @@ -418,6 +432,98 @@ int pvcalls_front_sendmsg(struct socket *sock, struct msghdr *msg, return tot_sent; } +static int __read_ring(struct pvcalls_data_intf *intf, + struct pvcalls_data *data, + struct iov_iter *msg_iter, + size_t len, int flags) +{ + RING_IDX cons, prod, size, masked_prod, masked_cons; + RING_IDX array_size = XEN_FLEX_RING_SIZE(intf->ring_order); + int32_t error; + + cons = intf->in_cons; + prod = intf->in_prod; + error = intf->in_error; + /* get pointers before reading from the ring */ + virt_rmb(); + if (error < 0) + return error; + + size = pvcalls_queued(prod, cons, array_size); + masked_prod = pvcalls_mask(prod, array_size); + masked_cons = pvcalls_mask(cons, array_size); + + if (size == 0) + return 0; + + if (len > size) + len = size; + + if (masked_prod > masked_cons) { + copy_to_iter(data->in + masked_cons, len, msg_iter); + } else { + if (len > (array_size - masked_cons)) { + copy_to_iter(data->in + masked_cons, + array_size - masked_cons, msg_iter); + copy_to_iter(data->in, + len - (array_size - masked_cons), + msg_iter); + } else { + copy_to_iter(data->in + masked_cons, len, msg_iter); + } + } + /* read data from the ring before increasing the index */ + virt_mb(); + if (!(flags & MSG_PEEK)) + intf->in_cons += len; + + return len; +} + +int pvcalls_front_recvmsg(struct socket *sock, struct msghdr *msg, size_t len, + int flags) +{ + struct pvcalls_bedata *bedata; + int ret = -EAGAIN; + struct sock_mapping *map; + int count = 0; + + 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 (flags & (MSG_CMSG_CLOEXEC|MSG_ERRQUEUE|MSG_OOB|MSG_TRUNC)) + return -EOPNOTSUPP; + + mutex_lock(&map->active.in_mutex); + if (len > XEN_FLEX_RING_SIZE(map->active.ring->ring_order)) + len = XEN_FLEX_RING_SIZE(map->active.ring->ring_order); + + while (!(flags & MSG_DONTWAIT) && !pvcalls_front_read_todo(map)) { + if (count < PVCALLS_FRONT_MAX_SPIN) + count++; + else + wait_event_interruptible(map->active.inflight_conn_req, + pvcalls_front_read_todo(map)); + } + ret = __read_ring(map->active.ring, &map->active.data, + &msg->msg_iter, len, flags); + + if (ret > 0) + notify_remote_via_irq(map->active.irq); + if (ret == 0) + ret = -EAGAIN; + if (ret == -ENOTCONN) + ret = 0; + + mutex_unlock(&map->active.in_mutex); + return ret; +} + int pvcalls_front_bind(struct socket *sock, struct sockaddr *addr, int addr_len) { struct pvcalls_bedata *bedata; diff --git a/drivers/xen/pvcalls-front.h b/drivers/xen/pvcalls-front.h index d937c24..de24041 100644 --- a/drivers/xen/pvcalls-front.h +++ b/drivers/xen/pvcalls-front.h @@ -16,5 +16,9 @@ int pvcalls_front_accept(struct socket *sock, int pvcalls_front_sendmsg(struct socket *sock, struct msghdr *msg, size_t len); +int pvcalls_front_recvmsg(struct socket *sock, + struct msghdr *msg, + size_t len, + int flags); #endif