lib/test_sysctl.c

   1 /*
   2  * proc sysctl test driver
   3  *
   4  * Copyright (C) 2017 Luis R. Rodriguez <mcgrof@kernel.org>
   5  *
   6  * This program is free software; you can redistribute it and/or modify it
   7  * under the terms of the GNU General Public License as published by the Free
   8  * Software Foundation; either version 2 of the License, or at your option any
   9  * later version; or, when distributed separately from the Linux kernel or
  10  * when incorporated into other software packages, subject to the following
  11  * license:
  12  *
  13  * This program is free software; you can redistribute it and/or modify it
  14  * under the terms of copyleft-next (version 0.3.1 or later) as published
  15  * at http://copyleft-next.org/.
  16  */
  17
  18 /*
  19  * This module provides an interface to the the proc sysctl interfaces.  This
  20  * driver requires CONFIG_PROC_SYSCTL. It will not normally be loaded by the
  21  * system unless explicitly requested by name. You can also build this driver
  22  * into your kernel.
  23  */
  24
  25 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  26
  27 #include <linux/init.h>
  28 #include <linux/list.h>
  29 #include <linux/module.h>
  30 #include <linux/printk.h>
  31 #include <linux/fs.h>
  32 #include <linux/miscdevice.h>
  33 #include <linux/slab.h>
  34 #include <linux/uaccess.h>
  35 #include <linux/async.h>
  36 #include <linux/delay.h>
  37 #include <linux/vmalloc.h>
  38
  39 static int i_zero;
  40 static int i_one_hundred = 100;
  41
  42 struct test_sysctl_data {
  43         int int_0001;
  44         char string_0001[65];
  45 };
  46
  47 static struct test_sysctl_data test_data = {
  48         .int_0001 = 60,
  49         .string_0001 = "(none)",
  50 };
  51
  52 /* These are all under /proc/sys/debug/test_sysctl/ */
  53 static struct ctl_table test_table[] = {
  54         {
  55                 .procname       = "int_0001",
  56                 .data           = &test_data.int_0001,
  57                 .maxlen         = sizeof(int),
  58                 .mode           = 0644,
  59                 .proc_handler   = proc_dointvec_minmax,
  60                 .extra1         = &i_zero,
  61                 .extra2         = &i_one_hundred,
  62         },
  63         {
  64                 .procname       = "string_0001",
  65                 .data           = &test_data.string_0001,
  66                 .maxlen         = sizeof(test_data.string_0001),
  67                 .mode           = 0644,
  68                 .proc_handler   = proc_dostring,
  69         },
  70         { }
  71 };
  72
  73 static struct ctl_table test_sysctl_table[] = {
  74         {
  75                 .procname       = "test_sysctl",
  76                 .maxlen         = 0,
  77                 .mode           = 0555,
  78                 .child          = test_table,
  79         },
  80         { }
  81 };
  82
  83 static struct ctl_table test_sysctl_root_table[] = {
  84         {
  85                 .procname       = "debug",
  86                 .maxlen         = 0,
  87                 .mode           = 0555,
  88                 .child          = test_sysctl_table,
  89         },
  90         { }
  91 };
  92
  93 static struct ctl_table_header *test_sysctl_header;
  94
  95 static int __init test_sysctl_init(void)
  96 {
  97         test_sysctl_header = register_sysctl_table(test_sysctl_root_table);
  98         if (!test_sysctl_header)
  99                 return -ENOMEM;
 100         return 0;
 101 }
 102 late_initcall(test_sysctl_init);
 103
 104 static void __exit test_sysctl_exit(void)
 105 {
 106         if (test_sysctl_header)
 107                 unregister_sysctl_table(test_sysctl_header);
 108 }
 109
 110 module_exit(test_sysctl_exit);
 111
 112 MODULE_AUTHOR("Luis R. Rodriguez <mcgrof@kernel.org>");
 113 MODULE_LICENSE("GPL");