[libata] pata_rb532_cf: fix signature of the xfer function
[linux-2.6.git] / kernel / softlockup.c
1 /*
2  * Detect Soft Lockups
3  *
4  * started by Ingo Molnar, Copyright (C) 2005, 2006 Red Hat, Inc.
5  *
6  * this code detects soft lockups: incidents in where on a CPU
7  * the kernel does not reschedule for 10 seconds or more.
8  */
9 #include <linux/mm.h>
10 #include <linux/cpu.h>
11 #include <linux/nmi.h>
12 #include <linux/init.h>
13 #include <linux/delay.h>
14 #include <linux/freezer.h>
15 #include <linux/kthread.h>
16 #include <linux/lockdep.h>
17 #include <linux/notifier.h>
18 #include <linux/module.h>
19
20 #include <asm/irq_regs.h>
21
22 static DEFINE_SPINLOCK(print_lock);
23
24 static DEFINE_PER_CPU(unsigned long, touch_timestamp);
25 static DEFINE_PER_CPU(unsigned long, print_timestamp);
26 static DEFINE_PER_CPU(struct task_struct *, watchdog_task);
27
28 static int __read_mostly did_panic;
29 int __read_mostly softlockup_thresh = 60;
30
31 /*
32  * Should we panic (and reboot, if panic_timeout= is set) when a
33  * soft-lockup occurs:
34  */
35 unsigned int __read_mostly softlockup_panic =
36                                 CONFIG_BOOTPARAM_SOFTLOCKUP_PANIC_VALUE;
37
38 static int __init softlockup_panic_setup(char *str)
39 {
40         softlockup_panic = simple_strtoul(str, NULL, 0);
41
42         return 1;
43 }
44 __setup("softlockup_panic=", softlockup_panic_setup);
45
46 static int
47 softlock_panic(struct notifier_block *this, unsigned long event, void *ptr)
48 {
49         did_panic = 1;
50
51         return NOTIFY_DONE;
52 }
53
54 static struct notifier_block panic_block = {
55         .notifier_call = softlock_panic,
56 };
57
58 /*
59  * Returns seconds, approximately.  We don't need nanosecond
60  * resolution, and we don't need to waste time with a big divide when
61  * 2^30ns == 1.074s.
62  */
63 static unsigned long get_timestamp(int this_cpu)
64 {
65         return cpu_clock(this_cpu) >> 30LL;  /* 2^30 ~= 10^9 */
66 }
67
68 static void __touch_softlockup_watchdog(void)
69 {
70         int this_cpu = raw_smp_processor_id();
71
72         __raw_get_cpu_var(touch_timestamp) = get_timestamp(this_cpu);
73 }
74
75 void touch_softlockup_watchdog(void)
76 {
77         __raw_get_cpu_var(touch_timestamp) = 0;
78 }
79 EXPORT_SYMBOL(touch_softlockup_watchdog);
80
81 void touch_all_softlockup_watchdogs(void)
82 {
83         int cpu;
84
85         /* Cause each CPU to re-update its timestamp rather than complain */
86         for_each_online_cpu(cpu)
87                 per_cpu(touch_timestamp, cpu) = 0;
88 }
89 EXPORT_SYMBOL(touch_all_softlockup_watchdogs);
90
91 /*
92  * This callback runs from the timer interrupt, and checks
93  * whether the watchdog thread has hung or not:
94  */
95 void softlockup_tick(void)
96 {
97         int this_cpu = smp_processor_id();
98         unsigned long touch_timestamp = per_cpu(touch_timestamp, this_cpu);
99         unsigned long print_timestamp;
100         struct pt_regs *regs = get_irq_regs();
101         unsigned long now;
102
103         /* Is detection switched off? */
104         if (!per_cpu(watchdog_task, this_cpu) || softlockup_thresh <= 0) {
105                 /* Be sure we don't false trigger if switched back on */
106                 if (touch_timestamp)
107                         per_cpu(touch_timestamp, this_cpu) = 0;
108                 return;
109         }
110
111         if (touch_timestamp == 0) {
112                 __touch_softlockup_watchdog();
113                 return;
114         }
115
116         print_timestamp = per_cpu(print_timestamp, this_cpu);
117
118         /* report at most once a second */
119         if (print_timestamp == touch_timestamp || did_panic)
120                 return;
121
122         /* do not print during early bootup: */
123         if (unlikely(system_state != SYSTEM_RUNNING)) {
124                 __touch_softlockup_watchdog();
125                 return;
126         }
127
128         now = get_timestamp(this_cpu);
129
130         /*
131          * Wake up the high-prio watchdog task twice per
132          * threshold timespan.
133          */
134         if (now > touch_timestamp + softlockup_thresh/2)
135                 wake_up_process(per_cpu(watchdog_task, this_cpu));
136
137         /* Warn about unreasonable delays: */
138         if (now <= (touch_timestamp + softlockup_thresh))
139                 return;
140
141         per_cpu(print_timestamp, this_cpu) = touch_timestamp;
142
143         spin_lock(&print_lock);
144         printk(KERN_ERR "BUG: soft lockup - CPU#%d stuck for %lus! [%s:%d]\n",
145                         this_cpu, now - touch_timestamp,
146                         current->comm, task_pid_nr(current));
147         print_modules();
148         print_irqtrace_events(current);
149         if (regs)
150                 show_regs(regs);
151         else
152                 dump_stack();
153         spin_unlock(&print_lock);
154
155         if (softlockup_panic)
156                 panic("softlockup: hung tasks");
157 }
158
159 /*
160  * Have a reasonable limit on the number of tasks checked:
161  */
162 unsigned long __read_mostly sysctl_hung_task_check_count = 1024;
163
164 /*
165  * Zero means infinite timeout - no checking done:
166  */
167 unsigned long __read_mostly sysctl_hung_task_timeout_secs = 120;
168
169 unsigned long __read_mostly sysctl_hung_task_warnings = 10;
170
171 /*
172  * Only do the hung-tasks check on one CPU:
173  */
174 static int check_cpu __read_mostly = -1;
175
176 static void check_hung_task(struct task_struct *t, unsigned long now)
177 {
178         unsigned long switch_count = t->nvcsw + t->nivcsw;
179
180         if (t->flags & PF_FROZEN)
181                 return;
182
183         if (switch_count != t->last_switch_count || !t->last_switch_timestamp) {
184                 t->last_switch_count = switch_count;
185                 t->last_switch_timestamp = now;
186                 return;
187         }
188         if ((long)(now - t->last_switch_timestamp) <
189                                         sysctl_hung_task_timeout_secs)
190                 return;
191         if (sysctl_hung_task_warnings < 0)
192                 return;
193         sysctl_hung_task_warnings--;
194
195         /*
196          * Ok, the task did not get scheduled for more than 2 minutes,
197          * complain:
198          */
199         printk(KERN_ERR "INFO: task %s:%d blocked for more than "
200                         "%ld seconds.\n", t->comm, t->pid,
201                         sysctl_hung_task_timeout_secs);
202         printk(KERN_ERR "\"echo 0 > /proc/sys/kernel/hung_task_timeout_secs\""
203                         " disables this message.\n");
204         sched_show_task(t);
205         __debug_show_held_locks(t);
206
207         t->last_switch_timestamp = now;
208         touch_nmi_watchdog();
209
210         if (softlockup_panic)
211                 panic("softlockup: blocked tasks");
212 }
213
214 /*
215  * Check whether a TASK_UNINTERRUPTIBLE does not get woken up for
216  * a really long time (120 seconds). If that happens, print out
217  * a warning.
218  */
219 static void check_hung_uninterruptible_tasks(int this_cpu)
220 {
221         int max_count = sysctl_hung_task_check_count;
222         unsigned long now = get_timestamp(this_cpu);
223         struct task_struct *g, *t;
224
225         /*
226          * If the system crashed already then all bets are off,
227          * do not report extra hung tasks:
228          */
229         if (test_taint(TAINT_DIE) || did_panic)
230                 return;
231
232         read_lock(&tasklist_lock);
233         do_each_thread(g, t) {
234                 if (!--max_count)
235                         goto unlock;
236                 /* use "==" to skip the TASK_KILLABLE tasks waiting on NFS */
237                 if (t->state == TASK_UNINTERRUPTIBLE)
238                         check_hung_task(t, now);
239         } while_each_thread(g, t);
240  unlock:
241         read_unlock(&tasklist_lock);
242 }
243
244 /*
245  * The watchdog thread - runs every second and touches the timestamp.
246  */
247 static int watchdog(void *__bind_cpu)
248 {
249         struct sched_param param = { .sched_priority = MAX_RT_PRIO-1 };
250         int this_cpu = (long)__bind_cpu;
251
252         sched_setscheduler(current, SCHED_FIFO, &param);
253
254         /* initialize timestamp */
255         __touch_softlockup_watchdog();
256
257         set_current_state(TASK_INTERRUPTIBLE);
258         /*
259          * Run briefly once per second to reset the softlockup timestamp.
260          * If this gets delayed for more than 60 seconds then the
261          * debug-printout triggers in softlockup_tick().
262          */
263         while (!kthread_should_stop()) {
264                 __touch_softlockup_watchdog();
265                 schedule();
266
267                 if (kthread_should_stop())
268                         break;
269
270                 if (this_cpu == check_cpu) {
271                         if (sysctl_hung_task_timeout_secs)
272                                 check_hung_uninterruptible_tasks(this_cpu);
273                 }
274
275                 set_current_state(TASK_INTERRUPTIBLE);
276         }
277         __set_current_state(TASK_RUNNING);
278
279         return 0;
280 }
281
282 /*
283  * Create/destroy watchdog threads as CPUs come and go:
284  */
285 static int __cpuinit
286 cpu_callback(struct notifier_block *nfb, unsigned long action, void *hcpu)
287 {
288         int hotcpu = (unsigned long)hcpu;
289         struct task_struct *p;
290
291         switch (action) {
292         case CPU_UP_PREPARE:
293         case CPU_UP_PREPARE_FROZEN:
294                 BUG_ON(per_cpu(watchdog_task, hotcpu));
295                 p = kthread_create(watchdog, hcpu, "watchdog/%d", hotcpu);
296                 if (IS_ERR(p)) {
297                         printk(KERN_ERR "watchdog for %i failed\n", hotcpu);
298                         return NOTIFY_BAD;
299                 }
300                 per_cpu(touch_timestamp, hotcpu) = 0;
301                 per_cpu(watchdog_task, hotcpu) = p;
302                 kthread_bind(p, hotcpu);
303                 break;
304         case CPU_ONLINE:
305         case CPU_ONLINE_FROZEN:
306                 check_cpu = any_online_cpu(cpu_online_map);
307                 wake_up_process(per_cpu(watchdog_task, hotcpu));
308                 break;
309 #ifdef CONFIG_HOTPLUG_CPU
310         case CPU_DOWN_PREPARE:
311         case CPU_DOWN_PREPARE_FROZEN:
312                 if (hotcpu == check_cpu) {
313                         cpumask_t temp_cpu_online_map = cpu_online_map;
314
315                         cpu_clear(hotcpu, temp_cpu_online_map);
316                         check_cpu = any_online_cpu(temp_cpu_online_map);
317                 }
318                 break;
319
320         case CPU_UP_CANCELED:
321         case CPU_UP_CANCELED_FROZEN:
322                 if (!per_cpu(watchdog_task, hotcpu))
323                         break;
324                 /* Unbind so it can run.  Fall thru. */
325                 kthread_bind(per_cpu(watchdog_task, hotcpu),
326                              any_online_cpu(cpu_online_map));
327         case CPU_DEAD:
328         case CPU_DEAD_FROZEN:
329                 p = per_cpu(watchdog_task, hotcpu);
330                 per_cpu(watchdog_task, hotcpu) = NULL;
331                 kthread_stop(p);
332                 break;
333 #endif /* CONFIG_HOTPLUG_CPU */
334         }
335         return NOTIFY_OK;
336 }
337
338 static struct notifier_block __cpuinitdata cpu_nfb = {
339         .notifier_call = cpu_callback
340 };
341
342 static int __initdata nosoftlockup;
343
344 static int __init nosoftlockup_setup(char *str)
345 {
346         nosoftlockup = 1;
347         return 1;
348 }
349 __setup("nosoftlockup", nosoftlockup_setup);
350
351 static int __init spawn_softlockup_task(void)
352 {
353         void *cpu = (void *)(long)smp_processor_id();
354         int err;
355
356         if (nosoftlockup)
357                 return 0;
358
359         err = cpu_callback(&cpu_nfb, CPU_UP_PREPARE, cpu);
360         if (err == NOTIFY_BAD) {
361                 BUG();
362                 return 1;
363         }
364         cpu_callback(&cpu_nfb, CPU_ONLINE, cpu);
365         register_cpu_notifier(&cpu_nfb);
366
367         atomic_notifier_chain_register(&panic_notifier_list, &panic_block);
368
369         return 0;
370 }
371 early_initcall(spawn_softlockup_task);