From patchwork Wed Jul 12 07:25:23 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Duan, Zhenzhong" X-Patchwork-Id: 13309674 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 4D251EB64D9 for ; Wed, 12 Jul 2023 07:42:14 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1qJUT8-0006zc-3N; Wed, 12 Jul 2023 03:41:02 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1qJUSo-0006av-M1 for qemu-devel@nongnu.org; Wed, 12 Jul 2023 03:40:44 -0400 Received: from mga07.intel.com ([134.134.136.100]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1qJUSi-0006qz-55 for qemu-devel@nongnu.org; Wed, 12 Jul 2023 03:40:37 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1689147636; x=1720683636; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=H9g5l3hj4qWFix41U6zqOzpKDRQVEwZP3YNyfk+8CgI=; b=O1SCOcYwYwSjBg7nV7GAXrCwNQXNnjF1pA1pmv7+0tyTTfAJ/nmvKmv8 q9NKPRf0GMYyMQOoTWqcWghWNIZut43quB3DPVo5x3btFuB9KLgkW7jp+ LMSbLXnmUGMTyJ7w8JEhi6HdIZBAO36gvqPAKpzBNOcHR3ERTUkWoY3ce 1eUKZKCGANx3szkmMV+pPg8+QleSGrWh2YCGf/kINprvJ89geIRVVjOSG 7CjTUBoJXShKo8+Cka2E+Tn88Wkle7Qsnh/220bBLD6uqRSL7QxUfFMVp H59UmzXe3xR6mPNW8Xs39CKPzGKlLAoiMeiFKk+8yOEqLimBy8zHe2V3v A==; X-IronPort-AV: E=McAfee;i="6600,9927,10768"; a="430953842" X-IronPort-AV: E=Sophos;i="6.01,199,1684825200"; d="scan'208";a="430953842" Received: from fmsmga002.fm.intel.com ([10.253.24.26]) by orsmga105.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 12 Jul 2023 00:40:08 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10768"; a="835024127" X-IronPort-AV: E=Sophos;i="6.01,199,1684825200"; d="scan'208";a="835024127" Received: from duan-server-s2600bt.bj.intel.com ([10.240.192.147]) by fmsmga002-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 12 Jul 2023 00:40:05 -0700 From: Zhenzhong Duan To: qemu-devel@nongnu.org Cc: alex.williamson@redhat.com, clg@redhat.com, jgg@nvidia.com, nicolinc@nvidia.com, eric.auger@redhat.com, peterx@redhat.com, jasonwang@redhat.com, kevin.tian@intel.com, yi.l.liu@intel.com, yi.y.sun@intel.com, chao.p.peng@intel.com, Zhenzhong Duan Subject: [RFC PATCH v4 19/24] util/char_dev: Add open_cdev() Date: Wed, 12 Jul 2023 15:25:23 +0800 Message-Id: <20230712072528.275577-20-zhenzhong.duan@intel.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20230712072528.275577-1-zhenzhong.duan@intel.com> References: <20230712072528.275577-1-zhenzhong.duan@intel.com> MIME-Version: 1.0 Received-SPF: pass client-ip=134.134.136.100; envelope-from=zhenzhong.duan@intel.com; helo=mga07.intel.com X-Spam_score_int: -43 X-Spam_score: -4.4 X-Spam_bar: ---- X-Spam_report: (-4.4 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_MED=-2.3, RCVD_IN_MSPIKE_H2=-0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org From: Yi Liu /dev/vfio/devices/vfioX may not exist. In that case it is still possible to open /dev/char/$major:$minor instead. Add helper function to abstract the cdev open. Suggested-by: Jason Gunthorpe Signed-off-by: Yi Liu Signed-off-by: Zhenzhong Duan --- MAINTAINERS | 6 ++++ include/qemu/char_dev.h | 16 +++++++++++ util/chardev_open.c | 61 +++++++++++++++++++++++++++++++++++++++++ util/meson.build | 1 + 4 files changed, 84 insertions(+) create mode 100644 include/qemu/char_dev.h create mode 100644 util/chardev_open.c diff --git a/MAINTAINERS b/MAINTAINERS index 25835caf39..edecf366b8 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -3356,6 +3356,12 @@ S: Maintained F: include/qemu/iova-tree.h F: util/iova-tree.c +cdev Open +M: Yi Liu +S: Maintained +F: include/qemu/char_dev.h +F: util/chardev_open.c + elf2dmp M: Viktor Prutyanov S: Maintained diff --git a/include/qemu/char_dev.h b/include/qemu/char_dev.h new file mode 100644 index 0000000000..6580d351c6 --- /dev/null +++ b/include/qemu/char_dev.h @@ -0,0 +1,16 @@ +/* + * QEMU Chardev Helper + * + * Copyright (C) 2023 Intel Corporation. + * + * Authors: Yi Liu + * + * This work is licensed under the terms of the GNU GPL, version 2. See + * the COPYING file in the top-level directory. + */ + +#ifndef QEMU_CHARDEV_HELPERS_H +#define QEMU_CHARDEV_HELPERS_H + +int open_cdev(const char *devpath, dev_t cdev); +#endif diff --git a/util/chardev_open.c b/util/chardev_open.c new file mode 100644 index 0000000000..d03e415131 --- /dev/null +++ b/util/chardev_open.c @@ -0,0 +1,61 @@ +/* + * Copyright (C) 2023 Intel Corporation. + * Copyright (c) 2019, Mellanox Technologies. All rights reserved. + * + * Authors: Yi Liu + * + * This work is licensed under the terms of the GNU GPL, version 2. See + * the COPYING file in the top-level directory. + * + * Copied from + * https://github.com/linux-rdma/rdma-core/blob/master/util/open_cdev.c + * + */ +#ifndef _GNU_SOURCE +#define _GNU_SOURCE +#endif +#include "qemu/osdep.h" +#include "qemu/char_dev.h" + +static int open_cdev_internal(const char *path, dev_t cdev) +{ + struct stat st; + int fd; + + fd = qemu_open_old(path, O_RDWR); + if (fd == -1) { + return -1; + } + if (fstat(fd, &st) || !S_ISCHR(st.st_mode) || + (cdev != 0 && st.st_rdev != cdev)) { + close(fd); + return -1; + } + return fd; +} + +static int open_cdev_robust(dev_t cdev) +{ + char *devpath; + int ret; + + /* + * This assumes that udev is being used and is creating the /dev/char/ + * symlinks. + */ + devpath = g_strdup_printf("/dev/char/%u:%u", major(cdev), minor(cdev)); + ret = open_cdev_internal(devpath, cdev); + g_free(devpath); + return ret; +} + +int open_cdev(const char *devpath, dev_t cdev) +{ + int fd; + + fd = open_cdev_internal(devpath, cdev); + if (fd == -1 && cdev != 0) { + return open_cdev_robust(cdev); + } + return fd; +} diff --git a/util/meson.build b/util/meson.build index a375160286..d5313d858f 100644 --- a/util/meson.build +++ b/util/meson.build @@ -107,6 +107,7 @@ if have_block util_ss.add(files('filemonitor-stub.c')) endif util_ss.add(when: 'CONFIG_LINUX', if_true: files('vfio-helpers.c')) + util_ss.add(when: 'CONFIG_LINUX', if_true: files('chardev_open.c')) endif if cpu == 'aarch64'