// SPDX-License-Identifier: GPL-2.0/* *  linux/fs/proc/kmsg.c * *  Copyright (C) 1992  by Linus Torvalds * */ #include <linux/types.h>#include <linux/errno.h>#include <linux/time.h>#include <linux/kernel.h>#include <linux/poll.h>#include <linux/proc_fs.h>#include <linux/fs.h>#include <linux/syslog.h> #include <linux/uaccess.h>#include <asm/io.h> extern wait_queue_head_t log_wait; static int kmsg_open(struct inode * inode, struct file * file){	return do_syslog(SYSLOG_ACTION_OPEN, NULL, 0, SYSLOG_FROM_PROC);} static int kmsg_release(struct inode * inode, struct file * file){	(void) do_syslog(SYSLOG_ACTION_CLOSE, NULL, 0, SYSLOG_FROM_PROC);	return 0;} static ssize_t kmsg_read(struct file *file, char __user *buf,			 size_t count, loff_t *ppos){	if ((file->f_flags & O_NONBLOCK) &&	    !do_syslog(SYSLOG_ACTION_SIZE_UNREAD, NULL, 0, SYSLOG_FROM_PROC))		return -EAGAIN;	return do_syslog(SYSLOG_ACTION_READ, buf, count, SYSLOG_FROM_PROC);} static __poll_t kmsg_poll(struct file *file, poll_table *wait){	poll_wait(file, &log_wait, wait);	if (do_syslog(SYSLOG_ACTION_SIZE_UNREAD, NULL, 0, SYSLOG_FROM_PROC))		return EPOLLIN | EPOLLRDNORM;	return 0;}  static const struct proc_ops kmsg_proc_ops = {	.proc_flags	= PROC_ENTRY_PERMANENT,	.proc_read	= kmsg_read,	.proc_poll	= kmsg_poll,	.proc_open	= kmsg_open,	.proc_release	= kmsg_release,	.proc_lseek	= generic_file_llseek,}; static int __init proc_kmsg_init(void){	proc_create("kmsg", S_IRUSR, NULL, &kmsg_proc_ops);	return 0;}fs_initcall(proc_kmsg_init);