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1// SPDX-License-Identifier: GPL-2.02/*3 * linux/fs/proc/kmsg.c4 *5 * Copyright (C) 1992 by Linus Torvalds6 *7 */8 9#include <linux/types.h>10#include <linux/errno.h>11#include <linux/time.h>12#include <linux/kernel.h>13#include <linux/poll.h>14#include <linux/proc_fs.h>15#include <linux/fs.h>16#include <linux/syslog.h>17 18#include <asm/io.h>19 20static int kmsg_open(struct inode * inode, struct file * file)21{22 return do_syslog(SYSLOG_ACTION_OPEN, NULL, 0, SYSLOG_FROM_PROC);23}24 25static int kmsg_release(struct inode * inode, struct file * file)26{27 (void) do_syslog(SYSLOG_ACTION_CLOSE, NULL, 0, SYSLOG_FROM_PROC);28 return 0;29}30 31static ssize_t kmsg_read(struct file *file, char __user *buf,32 size_t count, loff_t *ppos)33{34 if ((file->f_flags & O_NONBLOCK) &&35 !do_syslog(SYSLOG_ACTION_SIZE_UNREAD, NULL, 0, SYSLOG_FROM_PROC))36 return -EAGAIN;37 return do_syslog(SYSLOG_ACTION_READ, buf, count, SYSLOG_FROM_PROC);38}39 40static __poll_t kmsg_poll(struct file *file, poll_table *wait)41{42 poll_wait(file, &log_wait, wait);43 if (do_syslog(SYSLOG_ACTION_SIZE_UNREAD, NULL, 0, SYSLOG_FROM_PROC))44 return EPOLLIN | EPOLLRDNORM;45 return 0;46}47 48 49static const struct proc_ops kmsg_proc_ops = {50 .proc_flags = PROC_ENTRY_PERMANENT,51 .proc_read = kmsg_read,52 .proc_poll = kmsg_poll,53 .proc_open = kmsg_open,54 .proc_release = kmsg_release,55 .proc_lseek = generic_file_llseek,56};57 58static int __init proc_kmsg_init(void)59{60 proc_create("kmsg", S_IRUSR, NULL, &kmsg_proc_ops);61 return 0;62}63fs_initcall(proc_kmsg_init);64