1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
|
From a21e483b57c8c31beaa5063268ec35da375daf04 Mon Sep 17 00:00:00 2001
From: Bruce Ashfield <bruce.ashfield@windriver.com>
Date: Tue, 12 Jul 2011 10:26:50 -0400
Subject: [PATCH] uptime: allow the optional limiting of kernel runtime
Introduce the ability to limit the limit the uptime of a kernel.
When enabled, these options set a maximum uptime on the kernel, and
(optionally) trigger a clean reboot at expiration.
This functionality may appear to be very close to the softdog watchdog
implementation. It is. But can't be the softdog 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
To cleanly restart the kernel after one minute of uptime, the following
config items would be required:
CONFIG_UPTIME_LIMITED_KERNEL=y
CONFIG_UPTIME_LIMIT_DURATION=1
CONFIG_UPTIME_LIMIT_KERNEL_REBOOT=y
Signed-off-by: Bruce Ashfield <bruce.ashfield@windriver.com>
diff --git a/init/Kconfig b/init/Kconfig
index cac3f096050d..77d6d5fa1b1d 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -1376,6 +1376,31 @@ menuconfig EXPERT
environments which can tolerate a "non-standard" kernel.
Only use this if you really know what you are doing.
+config UPTIME_LIMITED_KERNEL
+ bool "Create a kernel with uptime limitations"
+ default n
+ help
+ Limit the amount of time a kernel can run. The associated UPTIME_LIMIT*
+ kernel config options should be used to tune the behaviour.
+
+config UPTIME_LIMIT_DURATION
+ int "Kernel uptime limit in minutes"
+ depends on UPTIME_LIMITED_KERNEL
+ range 0 14400
+ default 0
+ help
+ Define the uptime limitation on a kernel in minutes. Once
+ the defined time expires the kernel will emit a warning, cease
+ to be usable and eventually restart. The valid range is 0 (disable)
+ to 14400 (10 days)
+
+config UPTIME_LIMIT_KERNEL_REBOOT
+ bool "Reboot a time limited kernel at expiration"
+ depends on UPTIME_LIMITED_KERNEL
+ default y
+ help
+ Reboot an uptime limited kernel at expiration.
+
config UID16
bool "Enable 16-bit UID system calls" if EXPERT
depends on HAVE_UID16 && MULTIUSER
diff --git a/kernel/Makefile b/kernel/Makefile
index e2ec54e2b952..6b7bdddd624b 100644
--- a/kernel/Makefile
+++ b/kernel/Makefile
@@ -45,6 +45,7 @@ obj-$(CONFIG_FREEZER) += freezer.o
obj-$(CONFIG_PROFILING) += profile.o
obj-$(CONFIG_STACKTRACE) += stacktrace.o
obj-y += time/
+obj-$(CONFIG_UPTIME_LIMITED_KERNEL) += uptime_limit.o
obj-$(CONFIG_FUTEX) += futex.o
ifeq ($(CONFIG_COMPAT),y)
obj-$(CONFIG_FUTEX) += futex_compat.o
diff --git a/kernel/uptime_limit.c b/kernel/uptime_limit.c
new file mode 100644
index 000000000000..b6a1a5e4f9d9
--- /dev/null
+++ b/kernel/uptime_limit.c
@@ -0,0 +1,166 @@
+/*
+ * 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);
--
2.10.1
|
