samples/livepatch/livepatch-callbacks-busymod.c

   1 /*
   2  * Copyright (C) 2017 Joe Lawrence <joe.lawrence@redhat.com>
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public License
   6  * as published by the Free Software Foundation; either version 2
   7  * of the License, or (at your option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, see <http://www.gnu.org/licenses/>.
  16  */
  17
  18 /*
  19  * livepatch-callbacks-busymod.c - (un)patching callbacks demo support module
  20  *
  21  *
  22  * Purpose
  23  * -------
  24  *
  25  * Simple module to demonstrate livepatch (un)patching callbacks.
  26  *
  27  *
  28  * Usage
  29  * -----
  30  *
  31  * This module is not intended to be standalone.  See the "Usage"
  32  * section of livepatch-callbacks-mod.c.
  33  */
  34
  35 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  36
  37 #include <linux/module.h>
  38 #include <linux/kernel.h>
  39 #include <linux/workqueue.h>
  40 #include <linux/delay.h>
  41
  42 static int sleep_secs;
  43 module_param(sleep_secs, int, 0644);
  44 MODULE_PARM_DESC(sleep_secs, "sleep_secs (default=0)");
  45
  46 static void busymod_work_func(struct work_struct *work);
  47 static DECLARE_DELAYED_WORK(work, busymod_work_func);
  48
  49 static void busymod_work_func(struct work_struct *work)
  50 {
  51         pr_info("%s, sleeping %d seconds ...\n", __func__, sleep_secs);
  52         msleep(sleep_secs * 1000);
  53         pr_info("%s exit\n", __func__);
  54 }
  55
  56 static int livepatch_callbacks_mod_init(void)
  57 {
  58         pr_info("%s\n", __func__);
  59         schedule_delayed_work(&work,
  60                 msecs_to_jiffies(1000 * 0));
  61         return 0;
  62 }
  63
  64 static void livepatch_callbacks_mod_exit(void)
  65 {
  66         cancel_delayed_work_sync(&work);
  67         pr_info("%s\n", __func__);
  68 }
  69
  70 module_init(livepatch_callbacks_mod_init);
  71 module_exit(livepatch_callbacks_mod_exit);
  72 MODULE_LICENSE("GPL");