nohz: prevent tick stop outside of the idle loop
[linux-2.6] / kernel / time / timer_list.c
1 /*
2  * kernel/time/timer_list.c
3  *
4  * List pending timers
5  *
6  * Copyright(C) 2006, Red Hat, Inc., Ingo Molnar
7  *
8  * This program is free software; you can redistribute it and/or modify
9  * it under the terms of the GNU General Public License version 2 as
10  * published by the Free Software Foundation.
11  */
12
13 #include <linux/proc_fs.h>
14 #include <linux/module.h>
15 #include <linux/spinlock.h>
16 #include <linux/sched.h>
17 #include <linux/seq_file.h>
18 #include <linux/kallsyms.h>
19 #include <linux/tick.h>
20
21 #include <asm/uaccess.h>
22
23 typedef void (*print_fn_t)(struct seq_file *m, unsigned int *classes);
24
25 DECLARE_PER_CPU(struct hrtimer_cpu_base, hrtimer_bases);
26
27 /*
28  * This allows printing both to /proc/timer_list and
29  * to the console (on SysRq-Q):
30  */
31 #define SEQ_printf(m, x...)                     \
32  do {                                           \
33         if (m)                                  \
34                 seq_printf(m, x);               \
35         else                                    \
36                 printk(x);                      \
37  } while (0)
38
39 static void print_name_offset(struct seq_file *m, void *sym)
40 {
41         char symname[KSYM_NAME_LEN];
42
43         if (lookup_symbol_name((unsigned long)sym, symname) < 0)
44                 SEQ_printf(m, "<%p>", sym);
45         else
46                 SEQ_printf(m, "%s", symname);
47 }
48
49 static void
50 print_timer(struct seq_file *m, struct hrtimer *timer, int idx, u64 now)
51 {
52 #ifdef CONFIG_TIMER_STATS
53         char tmp[TASK_COMM_LEN + 1];
54 #endif
55         SEQ_printf(m, " #%d: ", idx);
56         print_name_offset(m, timer);
57         SEQ_printf(m, ", ");
58         print_name_offset(m, timer->function);
59         SEQ_printf(m, ", S:%02lx", timer->state);
60 #ifdef CONFIG_TIMER_STATS
61         SEQ_printf(m, ", ");
62         print_name_offset(m, timer->start_site);
63         memcpy(tmp, timer->start_comm, TASK_COMM_LEN);
64         tmp[TASK_COMM_LEN] = 0;
65         SEQ_printf(m, ", %s/%d", tmp, timer->start_pid);
66 #endif
67         SEQ_printf(m, "\n");
68         SEQ_printf(m, " # expires at %Lu nsecs [in %Ld nsecs]\n",
69                 (unsigned long long)ktime_to_ns(timer->expires),
70                 (long long)(ktime_to_ns(timer->expires) - now));
71 }
72
73 static void
74 print_active_timers(struct seq_file *m, struct hrtimer_clock_base *base,
75                     u64 now)
76 {
77         struct hrtimer *timer, tmp;
78         unsigned long next = 0, i;
79         struct rb_node *curr;
80         unsigned long flags;
81
82 next_one:
83         i = 0;
84         spin_lock_irqsave(&base->cpu_base->lock, flags);
85
86         curr = base->first;
87         /*
88          * Crude but we have to do this O(N*N) thing, because
89          * we have to unlock the base when printing:
90          */
91         while (curr && i < next) {
92                 curr = rb_next(curr);
93                 i++;
94         }
95
96         if (curr) {
97
98                 timer = rb_entry(curr, struct hrtimer, node);
99                 tmp = *timer;
100                 spin_unlock_irqrestore(&base->cpu_base->lock, flags);
101
102                 print_timer(m, &tmp, i, now);
103                 next++;
104                 goto next_one;
105         }
106         spin_unlock_irqrestore(&base->cpu_base->lock, flags);
107 }
108
109 static void
110 print_base(struct seq_file *m, struct hrtimer_clock_base *base, u64 now)
111 {
112         SEQ_printf(m, "  .index:      %d\n",
113                         base->index);
114         SEQ_printf(m, "  .resolution: %Lu nsecs\n",
115                         (unsigned long long)ktime_to_ns(base->resolution));
116         SEQ_printf(m,   "  .get_time:   ");
117         print_name_offset(m, base->get_time);
118         SEQ_printf(m,   "\n");
119 #ifdef CONFIG_HIGH_RES_TIMERS
120         SEQ_printf(m, "  .offset:     %Lu nsecs\n",
121                    (unsigned long long) ktime_to_ns(base->offset));
122 #endif
123         SEQ_printf(m,   "active timers:\n");
124         print_active_timers(m, base, now);
125 }
126
127 static void print_cpu(struct seq_file *m, int cpu, u64 now)
128 {
129         struct hrtimer_cpu_base *cpu_base = &per_cpu(hrtimer_bases, cpu);
130         int i;
131
132         SEQ_printf(m, "\n");
133         SEQ_printf(m, "cpu: %d\n", cpu);
134         for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++) {
135                 SEQ_printf(m, " clock %d:\n", i);
136                 print_base(m, cpu_base->clock_base + i, now);
137         }
138 #define P(x) \
139         SEQ_printf(m, "  .%-15s: %Lu\n", #x, \
140                    (unsigned long long)(cpu_base->x))
141 #define P_ns(x) \
142         SEQ_printf(m, "  .%-15s: %Lu nsecs\n", #x, \
143                    (unsigned long long)(ktime_to_ns(cpu_base->x)))
144
145 #ifdef CONFIG_HIGH_RES_TIMERS
146         P_ns(expires_next);
147         P(hres_active);
148         P(nr_events);
149 #endif
150 #undef P
151 #undef P_ns
152
153 #ifdef CONFIG_TICK_ONESHOT
154 # define P(x) \
155         SEQ_printf(m, "  .%-15s: %Lu\n", #x, \
156                    (unsigned long long)(ts->x))
157 # define P_ns(x) \
158         SEQ_printf(m, "  .%-15s: %Lu nsecs\n", #x, \
159                    (unsigned long long)(ktime_to_ns(ts->x)))
160         {
161                 struct tick_sched *ts = tick_get_tick_sched(cpu);
162                 P(nohz_mode);
163                 P_ns(idle_tick);
164                 P(tick_stopped);
165                 P(idle_jiffies);
166                 P(idle_calls);
167                 P(idle_sleeps);
168                 P_ns(idle_entrytime);
169                 P_ns(idle_waketime);
170                 P_ns(idle_exittime);
171                 P_ns(idle_sleeptime);
172                 P(last_jiffies);
173                 P(next_jiffies);
174                 P_ns(idle_expires);
175                 SEQ_printf(m, "jiffies: %Lu\n",
176                            (unsigned long long)jiffies);
177         }
178 #endif
179
180 #undef P
181 #undef P_ns
182 }
183
184 #ifdef CONFIG_GENERIC_CLOCKEVENTS
185 static void
186 print_tickdevice(struct seq_file *m, struct tick_device *td)
187 {
188         struct clock_event_device *dev = td->evtdev;
189
190         SEQ_printf(m, "\n");
191         SEQ_printf(m, "Tick Device: mode:     %d\n", td->mode);
192
193         SEQ_printf(m, "Clock Event Device: ");
194         if (!dev) {
195                 SEQ_printf(m, "<NULL>\n");
196                 return;
197         }
198         SEQ_printf(m, "%s\n", dev->name);
199         SEQ_printf(m, " max_delta_ns:   %lu\n", dev->max_delta_ns);
200         SEQ_printf(m, " min_delta_ns:   %lu\n", dev->min_delta_ns);
201         SEQ_printf(m, " mult:           %lu\n", dev->mult);
202         SEQ_printf(m, " shift:          %d\n", dev->shift);
203         SEQ_printf(m, " mode:           %d\n", dev->mode);
204         SEQ_printf(m, " next_event:     %Ld nsecs\n",
205                    (unsigned long long) ktime_to_ns(dev->next_event));
206
207         SEQ_printf(m, " set_next_event: ");
208         print_name_offset(m, dev->set_next_event);
209         SEQ_printf(m, "\n");
210
211         SEQ_printf(m, " set_mode:       ");
212         print_name_offset(m, dev->set_mode);
213         SEQ_printf(m, "\n");
214
215         SEQ_printf(m, " event_handler:  ");
216         print_name_offset(m, dev->event_handler);
217         SEQ_printf(m, "\n");
218 }
219
220 static void timer_list_show_tickdevices(struct seq_file *m)
221 {
222         int cpu;
223
224 #ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
225         print_tickdevice(m, tick_get_broadcast_device());
226         SEQ_printf(m, "tick_broadcast_mask: %08lx\n",
227                    tick_get_broadcast_mask()->bits[0]);
228 #ifdef CONFIG_TICK_ONESHOT
229         SEQ_printf(m, "tick_broadcast_oneshot_mask: %08lx\n",
230                    tick_get_broadcast_oneshot_mask()->bits[0]);
231 #endif
232         SEQ_printf(m, "\n");
233 #endif
234         for_each_online_cpu(cpu)
235                    print_tickdevice(m, tick_get_device(cpu));
236         SEQ_printf(m, "\n");
237 }
238 #else
239 static void timer_list_show_tickdevices(struct seq_file *m) { }
240 #endif
241
242 static int timer_list_show(struct seq_file *m, void *v)
243 {
244         u64 now = ktime_to_ns(ktime_get());
245         int cpu;
246
247         SEQ_printf(m, "Timer List Version: v0.3\n");
248         SEQ_printf(m, "HRTIMER_MAX_CLOCK_BASES: %d\n", HRTIMER_MAX_CLOCK_BASES);
249         SEQ_printf(m, "now at %Ld nsecs\n", (unsigned long long)now);
250
251         for_each_online_cpu(cpu)
252                 print_cpu(m, cpu, now);
253
254         SEQ_printf(m, "\n");
255         timer_list_show_tickdevices(m);
256
257         return 0;
258 }
259
260 void sysrq_timer_list_show(void)
261 {
262         timer_list_show(NULL, NULL);
263 }
264
265 static int timer_list_open(struct inode *inode, struct file *filp)
266 {
267         return single_open(filp, timer_list_show, NULL);
268 }
269
270 static struct file_operations timer_list_fops = {
271         .open           = timer_list_open,
272         .read           = seq_read,
273         .llseek         = seq_lseek,
274         .release        = single_release,
275 };
276
277 static int __init init_timer_list_procfs(void)
278 {
279         struct proc_dir_entry *pe;
280
281         pe = proc_create("timer_list", 0644, NULL, &timer_list_fops);
282         if (!pe)
283                 return -ENOMEM;
284         return 0;
285 }
286 __initcall(init_timer_list_procfs);