| /* |
| * uptime_limit.c |
| * |
| * This file contains the functions which can limit kernel uptime |
| * |
| * Copyright (C) 2011 Bruce Ashfield (bruce.ashfield@windriver.com) |
| * |
| * This program is free software; you can redistribute it and/or modify |
| * it under the terms of the GNU General Public License as published by |
| * the Free Software Foundation; either version 2 of the License, or |
| * (at your option) any later version. |
| * |
| * This program is distributed in the hope that it will be useful, |
| * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| * GNU General Public License for more details. |
| * |
| * You should have received a copy of the GNU General Public License |
| * along with this program; if not, write to the Free Software |
| * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. |
| * |
| * |
| * This functionality is somewhat close to the softdog watchdog |
| * implementation, but it cannot be used directly for several reasons: |
| * |
| * - The soft watchdog should be available while this functionality is active |
| * - The duration range is different between this and the softdog. The |
| * timeout available here is potentially quite a bit longer. |
| * - At expiration, there are different expiration requirements and actions. |
| * - This functionality is specific to a particular use case and should |
| * not impact mainline functionality |
| * |
| */ |
| #include <linux/kernel.h> |
| #include <linux/reboot.h> |
| #include <linux/timer.h> |
| #include <linux/delay.h> |
| #include <linux/kthread.h> |
| |
| #define UPTIME_LIMIT_IN_SECONDS (CONFIG_UPTIME_LIMIT_DURATION * 60) |
| #define MIN(X, Y) ((X) <= (Y) ? (X) : (Y)) |
| #define TEN_MINUTES_IN_SECONDS 600 |
| |
| enum uptime_expiration_type { |
| uptime_no_action, |
| uptime_reboot |
| }; |
| |
| static enum uptime_expiration_type uptime_expiration_action = uptime_no_action; |
| static struct timer_list timelimit_timer; |
| static struct task_struct *uptime_worker_task; |
| |
| static void timelimit_expire(unsigned long timeout_seconds) |
| { |
| char msg[128]; |
| int msglen = 127; |
| |
| if (timeout_seconds) { |
| if (timeout_seconds >= 60) |
| snprintf(msg, msglen, |
| "Uptime: kernel validity duration has %d %s remaining\n", |
| (int) timeout_seconds / 60, "minute(s)"); |
| else |
| snprintf(msg, msglen, |
| "Uptime: kernel validity duration has %d %s remaining\n", |
| (int) timeout_seconds, "seconds"); |
| |
| printk(KERN_CRIT "%s", msg); |
| |
| timelimit_timer.expires = jiffies + timeout_seconds * HZ; |
| timelimit_timer.data = 0; |
| add_timer_on(&timelimit_timer, cpumask_first(cpu_online_mask)); |
| } else { |
| printk(KERN_CRIT "Uptime: Kernel validity timeout has expired\n"); |
| #ifdef CONFIG_UPTIME_LIMIT_KERNEL_REBOOT |
| uptime_expiration_action = uptime_reboot; |
| wake_up_process(uptime_worker_task); |
| } |
| #endif |
| } |
| |
| /* |
| * This thread starts and then immediately goes to sleep. When it is woken |
| * up, it carries out the instructions left in uptime_expiration_action. If |
| * no action was specified it simply goes back to sleep. |
| */ |
| static int uptime_worker(void *unused) |
| { |
| set_current_state(TASK_INTERRUPTIBLE); |
| |
| while (!kthread_should_stop()) { |
| schedule(); |
| |
| if (kthread_should_stop()) |
| break; |
| |
| if (uptime_expiration_action == uptime_reboot) { |
| printk(KERN_CRIT "Uptime: restarting machine\n"); |
| kernel_restart(NULL); |
| } |
| |
| set_current_state(TASK_INTERRUPTIBLE); |
| } |
| __set_current_state(TASK_RUNNING); |
| |
| return 0; |
| } |
| |
| static int timeout_enable(int cpu) |
| { |
| int err = 0; |
| int warning_limit; |
| |
| /* |
| * Create an uptime worker thread. This thread is required since the |
| * safe version of kernel restart cannot be called from a |
| * non-interruptible context. Which means we cannot call it directly |
| * from a timer callback. So we arrange for the timer expiration to |
| * wakeup a thread, which performs the action. |
| */ |
| uptime_worker_task = kthread_create(uptime_worker, |
| (void *)(unsigned long)cpu, |
| "uptime_worker/%d", cpu); |
| if (IS_ERR(uptime_worker_task)) { |
| printk(KERN_ERR "Uptime: task for cpu %i failed\n", cpu); |
| err = PTR_ERR(uptime_worker_task); |
| goto out; |
| } |
| /* bind to cpu0 to avoid migration and hot plug nastiness */ |
| kthread_bind(uptime_worker_task, cpu); |
| wake_up_process(uptime_worker_task); |
| |
| /* Create the timer that will wake the uptime thread at expiration */ |
| init_timer(&timelimit_timer); |
| timelimit_timer.function = timelimit_expire; |
| /* |
| * Fire two timers. One warning timeout and the final timer |
| * which will carry out the expiration action. The warning timer will |
| * expire at the minimum of half the original time or ten minutes. |
| */ |
| warning_limit = MIN(UPTIME_LIMIT_IN_SECONDS/2, TEN_MINUTES_IN_SECONDS); |
| timelimit_timer.expires = jiffies + warning_limit * HZ; |
| timelimit_timer.data = UPTIME_LIMIT_IN_SECONDS - warning_limit; |
| |
| add_timer_on(&timelimit_timer, cpumask_first(cpu_online_mask)); |
| out: |
| return err; |
| } |
| |
| static int __init timelimit_init(void) |
| { |
| int err = 0; |
| |
| printk(KERN_INFO "Uptime: system uptime restrictions enabled\n"); |
| |
| /* |
| * Enable the timeout thread for cpu 0 only, assuming that the |
| * uptime limit is non-zero, to protect against any cpu |
| * migration issues. |
| */ |
| if (UPTIME_LIMIT_IN_SECONDS) |
| err = timeout_enable(0); |
| |
| return err; |
| } |
| device_initcall(timelimit_init); |