linux/fs/proc/kmsg.c
Linus Torvalds b520410654 printk changes for 6.1
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Merge tag 'printk-for-6.1' of git://git.kernel.org/pub/scm/linux/kernel/git/printk/linux

Pull printk updates from Petr Mladek:

 - Initialize pointer hashing using the system workqueue. It avoids
   taking locks in printk()/vsprintf() code path

 - Misc code clean up

* tag 'printk-for-6.1' of git://git.kernel.org/pub/scm/linux/kernel/git/printk/linux:
  printk: Mark __printk percpu data ready __ro_after_init
  printk: Remove bogus comment vs. boot consoles
  printk: Remove write only variable nr_ext_console_drivers
  printk: Declare log_wait properly
  printk: Make pr_flush() static
  lib/vsprintf: Initialize vsprintf's pointer hash once the random core is ready.
  lib/vsprintf: Remove static_branch_likely() from __ptr_to_hashval().
  lib/vnsprintf: add const modifier for param 'bitmap'
2022-10-10 11:24:19 -07:00

64 lines
1.5 KiB
C

// 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 <asm/io.h>
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);