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[RFC v2 12/15] util/char_dev: Add open_cdev()
From: |
Yi Liu |
Subject: |
[RFC v2 12/15] util/char_dev: Add open_cdev() |
Date: |
Wed, 8 Jun 2022 05:31:36 -0700 |
/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 <jgg@nvidia.com>
Signed-off-by: Yi Liu <yi.l.liu@intel.com>
---
MAINTAINERS | 6 +++++
include/qemu/char_dev.h | 16 ++++++++++++
util/chardev_open.c | 58 +++++++++++++++++++++++++++++++++++++++++
util/meson.build | 1 +
4 files changed, 81 insertions(+)
create mode 100644 include/qemu/char_dev.h
create mode 100644 util/chardev_open.c
diff --git a/MAINTAINERS b/MAINTAINERS
index c6aa4e7fd0..0b3ade4170 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -3171,6 +3171,12 @@ S: Maintained
F: include/qemu/iova-tree.h
F: util/iova-tree.c
+cdev Open
+M: Yi Liu <yi.l.liu@intel.com>
+S: Maintained
+F: include/qemu/char_dev.h
+F: util/chardev_open.c
+
elf2dmp
M: Viktor Prutyanov <viktor.prutyanov@phystech.edu>
S: Maintained
diff --git a/include/qemu/char_dev.h b/include/qemu/char_dev.h
new file mode 100644
index 0000000000..79877fb24d
--- /dev/null
+++ b/include/qemu/char_dev.h
@@ -0,0 +1,16 @@
+/*
+ * QEMU Chardev Helper
+ *
+ * Copyright (C) 2022 Intel Corporation.
+ *
+ * Authors: Yi Liu <yi.l.liu@intel.com>
+ *
+ * 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..133fad06ec
--- /dev/null
+++ b/util/chardev_open.c
@@ -0,0 +1,58 @@
+/*
+ * Copyright (C) 2022 Intel Corporation.
+ * Copyright (c) 2019, Mellanox Technologies. All rights reserved.
+ *
+ * Authors: Yi Liu <yi.l.liu@intel.com>
+ *
+ * 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 8f16018cd4..eff15d3826 100644
--- a/util/meson.build
+++ b/util/meson.build
@@ -95,4 +95,5 @@ 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
--
2.27.0
- [RFC v2 01/15] scripts/update-linux-headers: Add iommufd.h, (continued)
- [RFC v2 01/15] scripts/update-linux-headers: Add iommufd.h, Yi Liu, 2022/06/08
- [RFC v2 02/15] linux-headers: Import latest vfio.h and iommufd.h, Yi Liu, 2022/06/08
- [RFC v2 05/15] vfio/container: Introduce vfio_[attach/detach]_device, Yi Liu, 2022/06/08
- [RFC v2 03/15] vfio/common: Split common.c into common.c, container.c and as.c, Yi Liu, 2022/06/08
- [RFC v2 04/15] vfio: Add base container, Yi Liu, 2022/06/08
- [RFC v2 06/15] vfio/platform: Use vfio_[attach/detach]_device, Yi Liu, 2022/06/08
- [RFC v2 07/15] vfio/ap: Use vfio_[attach/detach]_device, Yi Liu, 2022/06/08
- [RFC v2 08/15] vfio/ccw: Use vfio_[attach/detach]_device, Yi Liu, 2022/06/08
- [RFC v2 09/15] vfio/container-base: Introduce [attach/detach]_device container callbacks, Yi Liu, 2022/06/08
- [RFC v2 10/15] vfio/container-base: Introduce VFIOContainer reset callback, Yi Liu, 2022/06/08
- [RFC v2 12/15] util/char_dev: Add open_cdev(),
Yi Liu <=
- [RFC v2 13/15] vfio/iommufd: Implement the iommufd backend, Yi Liu, 2022/06/08
- [RFC v2 11/15] backends/iommufd: Introduce the iommufd object, Yi Liu, 2022/06/08
- [RFC v2 14/15] vfio/iommufd: Add IOAS_COPY_DMA support, Yi Liu, 2022/06/08
- [RFC v2 15/15] vfio/as: Allow the selection of a given iommu backend, Yi Liu, 2022/06/08