linux-imx

// SPDX-License-Identifier: GPL-2.0

/*

 * devtmpfs - kernel-maintained tmpfs-based /dev

 *

 * Copyright (C) 2009, Kay Sievers <kay.sievers@vrfy.org>

 *

 * During bootup, before any driver core device is registered,

 * devtmpfs, a tmpfs-based filesystem is created. Every driver-core

 * device which requests a device node, will add a node in this

 * filesystem.

 * By default, all devices are named after the name of the device,

 * owned by root and have a default mode of 0600. Subsystems can

 * overwrite the default setting if needed.

 */

​

#include <linux/kernel.h>

#include <linux/syscalls.h>

#include <linux/mount.h>

#include <linux/device.h>

#include <linux/genhd.h>

#include <linux/namei.h>

#include <linux/fs.h>

#include <linux/shmem_fs.h>

#include <linux/ramfs.h>

#include <linux/sched.h>

#include <linux/slab.h>

#include <linux/kthread.h>

#include <uapi/linux/mount.h>

#include "base.h"

​

static struct task_struct *thread;

​

#if defined CONFIG_DEVTMPFS_MOUNT

static int mount_dev = 1;

#else

static int mount_dev;

#endif

​

static DEFINE_SPINLOCK(req_lock);

​

static struct req {

    struct req *next;

    struct completion done;

    int err;

    const char *name;

    umode_t mode;   /* 0 => delete */

    kuid_t uid;

    kgid_t gid;

    struct device *dev;

} *requests;

​

static int __init mount_param(char *str)

{

    mount_dev = simple_strtoul(str, NULL, 0);

    return 1;

}

__setup("devtmpfs.mount=", mount_param);

​

static struct dentry *dev_mount(struct file_system_type *fs_type, int flags,

              const char *dev_name, void *data)

{

#ifdef CONFIG_TMPFS

    return mount_single(fs_type, flags, data, shmem_fill_super);

#else

    return mount_single(fs_type, flags, data, ramfs_fill_super);

#endif

}

​

static struct file_system_type dev_fs_type = {

    .name = "devtmpfs",

    .mount = dev_mount,

    .kill_sb = kill_litter_super,

};

​

#ifdef CONFIG_BLOCK

static inline int is_blockdev(struct device *dev)

{

    return dev->class == &block_class;

}

#else

static inline int is_blockdev(struct device *dev) { return 0; }

#endif

​

int devtmpfs_create_node(struct device *dev)

{

    const char *tmp = NULL;

    struct req req;

​

    if (!thread)

        return 0;

​

    req.mode = 0;