From patchwork Mon Nov 28 19:42:25 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Stefano Stabellini X-Patchwork-Id: 9450145 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 D4DBF60235 for ; Mon, 28 Nov 2016 19:48:31 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id C3A1A26419 for ; Mon, 28 Nov 2016 19:48:31 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id B7F8D27FBB; Mon, 28 Nov 2016 19:48:31 +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=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from lists.gnu.org (lists.gnu.org [208.118.235.17]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 2C6BE27FB3 for ; Mon, 28 Nov 2016 19:48:30 +0000 (UTC) Received: from localhost ([::1]:60844 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1cBRuf-0001B7-0h for patchwork-qemu-devel@patchwork.kernel.org; Mon, 28 Nov 2016 14:48:29 -0500 Received: from eggs.gnu.org ([2001:4830:134:3::10]:56623) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1cBRox-0005xa-6O for qemu-devel@nongnu.org; Mon, 28 Nov 2016 14:42:36 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1cBRow-0005Wl-74 for qemu-devel@nongnu.org; Mon, 28 Nov 2016 14:42:35 -0500 Received: from mail.kernel.org ([198.145.29.136]:50116) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1cBRow-0005WQ-0k for qemu-devel@nongnu.org; Mon, 28 Nov 2016 14:42:34 -0500 Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 26A162017D; Mon, 28 Nov 2016 19:42:32 +0000 (UTC) Received: from sstabellini-ThinkPad-X260.hsd1.ca.comcast.net (96-82-76-110-static.hfc.comcastbusiness.net [96.82.76.110]) (using TLSv1.2 with cipher AES128-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 6E122201BC; Mon, 28 Nov 2016 19:42:30 +0000 (UTC) From: Stefano Stabellini To: stefanha@gmail.com Date: Mon, 28 Nov 2016 11:42:25 -0800 Message-Id: <1480362146-14873-3-git-send-email-sstabellini@kernel.org> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1480362146-14873-1-git-send-email-sstabellini@kernel.org> References: <1480362146-14873-1-git-send-email-sstabellini@kernel.org> X-Virus-Scanned: ClamAV using ClamSMTP X-detected-operating-system: by eggs.gnu.org: GNU/Linux 3.x [fuzzy] X-Received-From: 198.145.29.136 Subject: [Qemu-devel] [PULL 3/4] xen: slightly simplify bufioreq handling X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: peter.maydell@linaro.org, sstabellini@kernel.org, Jan Beulich , qemu-devel@nongnu.org, stefanha@redhat.com, anthony.perard@citrix.com, xen-devel@lists.xenproject.org Errors-To: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Sender: "Qemu-devel" X-Virus-Scanned: ClamAV using ClamSMTP From: Jan Beulich There's no point setting fields always receiving the same value on each iteration, as handle_ioreq() doesn't alter them anyway. Set state and count once ahead of the loop, drop the redundant clearing of data_is_ptr, and avoid the meaningless (because count is 1) setting of df altogether. Also avoid doing an unsigned long calculation of size when the field to be initialized is only 32 bits wide (and the shift value in the range 0...3). Signed-off-by: Jan Beulich Reviewed-by: Paul Durrant Reviewed-by: Stefano Stabellini Signed-off-by: Stefano Stabellini --- xen-hvm.c | 15 ++++++++++----- 1 file changed, 10 insertions(+), 5 deletions(-) diff --git a/xen-hvm.c b/xen-hvm.c index d74e233..124ae10 100644 --- a/xen-hvm.c +++ b/xen-hvm.c @@ -995,6 +995,8 @@ static int handle_buffered_iopage(XenIOState *state) } memset(&req, 0x00, sizeof(req)); + req.state = STATE_IOREQ_READY; + req.count = 1; for (;;) { uint32_t rdptr = buf_page->read_pointer, wrptr; @@ -1009,15 +1011,11 @@ static int handle_buffered_iopage(XenIOState *state) break; } buf_req = &buf_page->buf_ioreq[rdptr % IOREQ_BUFFER_SLOT_NUM]; - req.size = 1UL << buf_req->size; - req.count = 1; + req.size = 1U << buf_req->size; req.addr = buf_req->addr; req.data = buf_req->data; - req.state = STATE_IOREQ_READY; req.dir = buf_req->dir; - req.df = 1; req.type = buf_req->type; - req.data_is_ptr = 0; xen_rmb(); qw = (req.size == 8); if (qw) { @@ -1032,6 +1030,13 @@ static int handle_buffered_iopage(XenIOState *state) handle_ioreq(state, &req); + /* Only req.data may get updated by handle_ioreq(), albeit even that + * should not happen as such data would never make it to the guest. + */ + assert(req.state == STATE_IOREQ_READY); + assert(req.count == 1); + assert(!req.data_is_ptr); + atomic_add(&buf_page->read_pointer, qw + 1); }