62 lines
1.3 KiB
C
62 lines
1.3 KiB
C
// SPDX-License-Identifier: GPL-2.0
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#include <linux/init.h>
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#include <linux/module.h>
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#include <linux/fs.h>
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#include <linux/uaccess.h>
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#include <linux/debugfs.h>
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#include <linux/mm.h>
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#include <linux/mutex.h>
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extern struct dentry *module_dir;
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ssize_t foo_read(struct file *f, char __user *buf, size_t len, loff_t *off);
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ssize_t foo_write(struct file *f, const char __user *buf, size_t len, loff_t *off);
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int init_foo(void);
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char buffer[PAGE_SIZE];
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size_t buffer_len;
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DEFINE_MUTEX(rw_lock);
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static const struct file_operations fops = {
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.owner = THIS_MODULE,
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.read = foo_read,
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.write = foo_write,
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};
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ssize_t foo_read(struct file *f, char __user *buf, size_t len, loff_t *off)
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{
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size_t read;
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mutex_lock(&rw_lock);
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read = simple_read_from_buffer(buf, len, off, buffer, buffer_len);
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mutex_unlock(&rw_lock);
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return read;
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}
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ssize_t foo_write(struct file *f, const char __user *buf, size_t len, loff_t *off)
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{
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if (len > sizeof(buffer))
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return -EINVAL;
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mutex_lock(&rw_lock);
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if (copy_from_user(buffer, buf, len)) {
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mutex_unlock(&rw_lock);
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return -EINVAL;
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}
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buffer_len = len;
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mutex_unlock(&rw_lock);
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return len;
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}
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int init_foo(void)
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{
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struct dentry *ret;
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mutex_init(&rw_lock);
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ret = debugfs_create_file("foo", 0644, module_dir, NULL, &fops);
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if (IS_ERR(ret))
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return PTR_ERR(ret);
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return 0;
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}
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