rcu: Fix day-one dyntick-idle stall-warning bug
[linux-2.6.git] / kernel / rcutree_trace.c
1 /*
2  * Read-Copy Update tracing for classic implementation
3  *
4  * This program is free software; you can redistribute it and/or modify
5  * it under the terms of the GNU General Public License as published by
6  * the Free Software Foundation; either version 2 of the License, or
7  * (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, write to the Free Software
16  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
17  *
18  * Copyright IBM Corporation, 2008
19  *
20  * Papers:  http://www.rdrop.com/users/paulmck/RCU
21  *
22  * For detailed explanation of Read-Copy Update mechanism see -
23  *              Documentation/RCU
24  *
25  */
26 #include <linux/types.h>
27 #include <linux/kernel.h>
28 #include <linux/init.h>
29 #include <linux/spinlock.h>
30 #include <linux/smp.h>
31 #include <linux/rcupdate.h>
32 #include <linux/interrupt.h>
33 #include <linux/sched.h>
34 #include <linux/atomic.h>
35 #include <linux/bitops.h>
36 #include <linux/module.h>
37 #include <linux/completion.h>
38 #include <linux/moduleparam.h>
39 #include <linux/percpu.h>
40 #include <linux/notifier.h>
41 #include <linux/cpu.h>
42 #include <linux/mutex.h>
43 #include <linux/debugfs.h>
44 #include <linux/seq_file.h>
45
46 #define RCU_TREE_NONCORE
47 #include "rcutree.h"
48
49 #ifdef CONFIG_RCU_BOOST
50
51 static char convert_kthread_status(unsigned int kthread_status)
52 {
53         if (kthread_status > RCU_KTHREAD_MAX)
54                 return '?';
55         return "SRWOY"[kthread_status];
56 }
57
58 #endif /* #ifdef CONFIG_RCU_BOOST */
59
60 static void print_one_rcu_data(struct seq_file *m, struct rcu_data *rdp)
61 {
62         if (!rdp->beenonline)
63                 return;
64         seq_printf(m, "%3d%cc=%lu g=%lu pq=%d pgp=%lu qp=%d",
65                    rdp->cpu,
66                    cpu_is_offline(rdp->cpu) ? '!' : ' ',
67                    rdp->completed, rdp->gpnum,
68                    rdp->passed_quiesce, rdp->passed_quiesce_gpnum,
69                    rdp->qs_pending);
70         seq_printf(m, " dt=%d/%llx/%d df=%lu",
71                    atomic_read(&rdp->dynticks->dynticks),
72                    rdp->dynticks->dynticks_nesting,
73                    rdp->dynticks->dynticks_nmi_nesting,
74                    rdp->dynticks_fqs);
75         seq_printf(m, " of=%lu", rdp->offline_fqs);
76         seq_printf(m, " ql=%ld/%ld qs=%c%c%c%c",
77                    rdp->qlen_lazy, rdp->qlen,
78                    ".N"[rdp->nxttail[RCU_NEXT_READY_TAIL] !=
79                         rdp->nxttail[RCU_NEXT_TAIL]],
80                    ".R"[rdp->nxttail[RCU_WAIT_TAIL] !=
81                         rdp->nxttail[RCU_NEXT_READY_TAIL]],
82                    ".W"[rdp->nxttail[RCU_DONE_TAIL] !=
83                         rdp->nxttail[RCU_WAIT_TAIL]],
84                    ".D"[&rdp->nxtlist != rdp->nxttail[RCU_DONE_TAIL]]);
85 #ifdef CONFIG_RCU_BOOST
86         seq_printf(m, " kt=%d/%c/%d ktl=%x",
87                    per_cpu(rcu_cpu_has_work, rdp->cpu),
88                    convert_kthread_status(per_cpu(rcu_cpu_kthread_status,
89                                           rdp->cpu)),
90                    per_cpu(rcu_cpu_kthread_cpu, rdp->cpu),
91                    per_cpu(rcu_cpu_kthread_loops, rdp->cpu) & 0xffff);
92 #endif /* #ifdef CONFIG_RCU_BOOST */
93         seq_printf(m, " b=%ld", rdp->blimit);
94         seq_printf(m, " ci=%lu co=%lu ca=%lu\n",
95                    rdp->n_cbs_invoked, rdp->n_cbs_orphaned, rdp->n_cbs_adopted);
96 }
97
98 #define PRINT_RCU_DATA(name, func, m) \
99         do { \
100                 int _p_r_d_i; \
101                 \
102                 for_each_possible_cpu(_p_r_d_i) \
103                         func(m, &per_cpu(name, _p_r_d_i)); \
104         } while (0)
105
106 static int show_rcudata(struct seq_file *m, void *unused)
107 {
108 #ifdef CONFIG_TREE_PREEMPT_RCU
109         seq_puts(m, "rcu_preempt:\n");
110         PRINT_RCU_DATA(rcu_preempt_data, print_one_rcu_data, m);
111 #endif /* #ifdef CONFIG_TREE_PREEMPT_RCU */
112         seq_puts(m, "rcu_sched:\n");
113         PRINT_RCU_DATA(rcu_sched_data, print_one_rcu_data, m);
114         seq_puts(m, "rcu_bh:\n");
115         PRINT_RCU_DATA(rcu_bh_data, print_one_rcu_data, m);
116         return 0;
117 }
118
119 static int rcudata_open(struct inode *inode, struct file *file)
120 {
121         return single_open(file, show_rcudata, NULL);
122 }
123
124 static const struct file_operations rcudata_fops = {
125         .owner = THIS_MODULE,
126         .open = rcudata_open,
127         .read = seq_read,
128         .llseek = seq_lseek,
129         .release = single_release,
130 };
131
132 static void print_one_rcu_data_csv(struct seq_file *m, struct rcu_data *rdp)
133 {
134         if (!rdp->beenonline)
135                 return;
136         seq_printf(m, "%d,%s,%lu,%lu,%d,%lu,%d",
137                    rdp->cpu,
138                    cpu_is_offline(rdp->cpu) ? "\"N\"" : "\"Y\"",
139                    rdp->completed, rdp->gpnum,
140                    rdp->passed_quiesce, rdp->passed_quiesce_gpnum,
141                    rdp->qs_pending);
142         seq_printf(m, ",%d,%llx,%d,%lu",
143                    atomic_read(&rdp->dynticks->dynticks),
144                    rdp->dynticks->dynticks_nesting,
145                    rdp->dynticks->dynticks_nmi_nesting,
146                    rdp->dynticks_fqs);
147         seq_printf(m, ",%lu", rdp->offline_fqs);
148         seq_printf(m, ",%ld,%ld,\"%c%c%c%c\"", rdp->qlen_lazy, rdp->qlen,
149                    ".N"[rdp->nxttail[RCU_NEXT_READY_TAIL] !=
150                         rdp->nxttail[RCU_NEXT_TAIL]],
151                    ".R"[rdp->nxttail[RCU_WAIT_TAIL] !=
152                         rdp->nxttail[RCU_NEXT_READY_TAIL]],
153                    ".W"[rdp->nxttail[RCU_DONE_TAIL] !=
154                         rdp->nxttail[RCU_WAIT_TAIL]],
155                    ".D"[&rdp->nxtlist != rdp->nxttail[RCU_DONE_TAIL]]);
156 #ifdef CONFIG_RCU_BOOST
157         seq_printf(m, ",%d,\"%c\"",
158                    per_cpu(rcu_cpu_has_work, rdp->cpu),
159                    convert_kthread_status(per_cpu(rcu_cpu_kthread_status,
160                                           rdp->cpu)));
161 #endif /* #ifdef CONFIG_RCU_BOOST */
162         seq_printf(m, ",%ld", rdp->blimit);
163         seq_printf(m, ",%lu,%lu,%lu\n",
164                    rdp->n_cbs_invoked, rdp->n_cbs_orphaned, rdp->n_cbs_adopted);
165 }
166
167 static int show_rcudata_csv(struct seq_file *m, void *unused)
168 {
169         seq_puts(m, "\"CPU\",\"Online?\",\"c\",\"g\",\"pq\",\"pgp\",\"pq\",");
170         seq_puts(m, "\"dt\",\"dt nesting\",\"dt NMI nesting\",\"df\",");
171         seq_puts(m, "\"of\",\"qll\",\"ql\",\"qs\"");
172 #ifdef CONFIG_RCU_BOOST
173         seq_puts(m, "\"kt\",\"ktl\"");
174 #endif /* #ifdef CONFIG_RCU_BOOST */
175         seq_puts(m, ",\"b\",\"ci\",\"co\",\"ca\"\n");
176 #ifdef CONFIG_TREE_PREEMPT_RCU
177         seq_puts(m, "\"rcu_preempt:\"\n");
178         PRINT_RCU_DATA(rcu_preempt_data, print_one_rcu_data_csv, m);
179 #endif /* #ifdef CONFIG_TREE_PREEMPT_RCU */
180         seq_puts(m, "\"rcu_sched:\"\n");
181         PRINT_RCU_DATA(rcu_sched_data, print_one_rcu_data_csv, m);
182         seq_puts(m, "\"rcu_bh:\"\n");
183         PRINT_RCU_DATA(rcu_bh_data, print_one_rcu_data_csv, m);
184         return 0;
185 }
186
187 static int rcudata_csv_open(struct inode *inode, struct file *file)
188 {
189         return single_open(file, show_rcudata_csv, NULL);
190 }
191
192 static const struct file_operations rcudata_csv_fops = {
193         .owner = THIS_MODULE,
194         .open = rcudata_csv_open,
195         .read = seq_read,
196         .llseek = seq_lseek,
197         .release = single_release,
198 };
199
200 #ifdef CONFIG_RCU_BOOST
201
202 static void print_one_rcu_node_boost(struct seq_file *m, struct rcu_node *rnp)
203 {
204         seq_printf(m,  "%d:%d tasks=%c%c%c%c kt=%c ntb=%lu neb=%lu nnb=%lu "
205                    "j=%04x bt=%04x\n",
206                    rnp->grplo, rnp->grphi,
207                    "T."[list_empty(&rnp->blkd_tasks)],
208                    "N."[!rnp->gp_tasks],
209                    "E."[!rnp->exp_tasks],
210                    "B."[!rnp->boost_tasks],
211                    convert_kthread_status(rnp->boost_kthread_status),
212                    rnp->n_tasks_boosted, rnp->n_exp_boosts,
213                    rnp->n_normal_boosts,
214                    (int)(jiffies & 0xffff),
215                    (int)(rnp->boost_time & 0xffff));
216         seq_printf(m, "%s: nt=%lu egt=%lu bt=%lu nb=%lu ny=%lu nos=%lu\n",
217                    "     balk",
218                    rnp->n_balk_blkd_tasks,
219                    rnp->n_balk_exp_gp_tasks,
220                    rnp->n_balk_boost_tasks,
221                    rnp->n_balk_notblocked,
222                    rnp->n_balk_notyet,
223                    rnp->n_balk_nos);
224 }
225
226 static int show_rcu_node_boost(struct seq_file *m, void *unused)
227 {
228         struct rcu_node *rnp;
229
230         rcu_for_each_leaf_node(&rcu_preempt_state, rnp)
231                 print_one_rcu_node_boost(m, rnp);
232         return 0;
233 }
234
235 static int rcu_node_boost_open(struct inode *inode, struct file *file)
236 {
237         return single_open(file, show_rcu_node_boost, NULL);
238 }
239
240 static const struct file_operations rcu_node_boost_fops = {
241         .owner = THIS_MODULE,
242         .open = rcu_node_boost_open,
243         .read = seq_read,
244         .llseek = seq_lseek,
245         .release = single_release,
246 };
247
248 /*
249  * Create the rcuboost debugfs entry.  Standard error return.
250  */
251 static int rcu_boost_trace_create_file(struct dentry *rcudir)
252 {
253         return !debugfs_create_file("rcuboost", 0444, rcudir, NULL,
254                                     &rcu_node_boost_fops);
255 }
256
257 #else /* #ifdef CONFIG_RCU_BOOST */
258
259 static int rcu_boost_trace_create_file(struct dentry *rcudir)
260 {
261         return 0;  /* There cannot be an error if we didn't create it! */
262 }
263
264 #endif /* #else #ifdef CONFIG_RCU_BOOST */
265
266 static void print_one_rcu_state(struct seq_file *m, struct rcu_state *rsp)
267 {
268         unsigned long gpnum;
269         int level = 0;
270         struct rcu_node *rnp;
271
272         gpnum = rsp->gpnum;
273         seq_printf(m, "c=%lu g=%lu s=%d jfq=%ld j=%x "
274                       "nfqs=%lu/nfqsng=%lu(%lu) fqlh=%lu\n",
275                    rsp->completed, gpnum, rsp->fqs_state,
276                    (long)(rsp->jiffies_force_qs - jiffies),
277                    (int)(jiffies & 0xffff),
278                    rsp->n_force_qs, rsp->n_force_qs_ngp,
279                    rsp->n_force_qs - rsp->n_force_qs_ngp,
280                    rsp->n_force_qs_lh);
281         for (rnp = &rsp->node[0]; rnp - &rsp->node[0] < NUM_RCU_NODES; rnp++) {
282                 if (rnp->level != level) {
283                         seq_puts(m, "\n");
284                         level = rnp->level;
285                 }
286                 seq_printf(m, "%lx/%lx %c%c>%c %d:%d ^%d    ",
287                            rnp->qsmask, rnp->qsmaskinit,
288                            ".G"[rnp->gp_tasks != NULL],
289                            ".E"[rnp->exp_tasks != NULL],
290                            ".T"[!list_empty(&rnp->blkd_tasks)],
291                            rnp->grplo, rnp->grphi, rnp->grpnum);
292         }
293         seq_puts(m, "\n");
294 }
295
296 static int show_rcuhier(struct seq_file *m, void *unused)
297 {
298 #ifdef CONFIG_TREE_PREEMPT_RCU
299         seq_puts(m, "rcu_preempt:\n");
300         print_one_rcu_state(m, &rcu_preempt_state);
301 #endif /* #ifdef CONFIG_TREE_PREEMPT_RCU */
302         seq_puts(m, "rcu_sched:\n");
303         print_one_rcu_state(m, &rcu_sched_state);
304         seq_puts(m, "rcu_bh:\n");
305         print_one_rcu_state(m, &rcu_bh_state);
306         return 0;
307 }
308
309 static int rcuhier_open(struct inode *inode, struct file *file)
310 {
311         return single_open(file, show_rcuhier, NULL);
312 }
313
314 static const struct file_operations rcuhier_fops = {
315         .owner = THIS_MODULE,
316         .open = rcuhier_open,
317         .read = seq_read,
318         .llseek = seq_lseek,
319         .release = single_release,
320 };
321
322 static void show_one_rcugp(struct seq_file *m, struct rcu_state *rsp)
323 {
324         unsigned long flags;
325         unsigned long completed;
326         unsigned long gpnum;
327         unsigned long gpage;
328         unsigned long gpmax;
329         struct rcu_node *rnp = &rsp->node[0];
330
331         raw_spin_lock_irqsave(&rnp->lock, flags);
332         completed = rsp->completed;
333         gpnum = rsp->gpnum;
334         if (rsp->completed == rsp->gpnum)
335                 gpage = 0;
336         else
337                 gpage = jiffies - rsp->gp_start;
338         gpmax = rsp->gp_max;
339         raw_spin_unlock_irqrestore(&rnp->lock, flags);
340         seq_printf(m, "%s: completed=%ld  gpnum=%lu  age=%ld  max=%ld\n",
341                    rsp->name, completed, gpnum, gpage, gpmax);
342 }
343
344 static int show_rcugp(struct seq_file *m, void *unused)
345 {
346 #ifdef CONFIG_TREE_PREEMPT_RCU
347         show_one_rcugp(m, &rcu_preempt_state);
348 #endif /* #ifdef CONFIG_TREE_PREEMPT_RCU */
349         show_one_rcugp(m, &rcu_sched_state);
350         show_one_rcugp(m, &rcu_bh_state);
351         return 0;
352 }
353
354 static int rcugp_open(struct inode *inode, struct file *file)
355 {
356         return single_open(file, show_rcugp, NULL);
357 }
358
359 static const struct file_operations rcugp_fops = {
360         .owner = THIS_MODULE,
361         .open = rcugp_open,
362         .read = seq_read,
363         .llseek = seq_lseek,
364         .release = single_release,
365 };
366
367 static void print_one_rcu_pending(struct seq_file *m, struct rcu_data *rdp)
368 {
369         seq_printf(m, "%3d%cnp=%ld "
370                    "qsp=%ld rpq=%ld cbr=%ld cng=%ld "
371                    "gpc=%ld gps=%ld nf=%ld nn=%ld\n",
372                    rdp->cpu,
373                    cpu_is_offline(rdp->cpu) ? '!' : ' ',
374                    rdp->n_rcu_pending,
375                    rdp->n_rp_qs_pending,
376                    rdp->n_rp_report_qs,
377                    rdp->n_rp_cb_ready,
378                    rdp->n_rp_cpu_needs_gp,
379                    rdp->n_rp_gp_completed,
380                    rdp->n_rp_gp_started,
381                    rdp->n_rp_need_fqs,
382                    rdp->n_rp_need_nothing);
383 }
384
385 static void print_rcu_pendings(struct seq_file *m, struct rcu_state *rsp)
386 {
387         int cpu;
388         struct rcu_data *rdp;
389
390         for_each_possible_cpu(cpu) {
391                 rdp = per_cpu_ptr(rsp->rda, cpu);
392                 if (rdp->beenonline)
393                         print_one_rcu_pending(m, rdp);
394         }
395 }
396
397 static int show_rcu_pending(struct seq_file *m, void *unused)
398 {
399 #ifdef CONFIG_TREE_PREEMPT_RCU
400         seq_puts(m, "rcu_preempt:\n");
401         print_rcu_pendings(m, &rcu_preempt_state);
402 #endif /* #ifdef CONFIG_TREE_PREEMPT_RCU */
403         seq_puts(m, "rcu_sched:\n");
404         print_rcu_pendings(m, &rcu_sched_state);
405         seq_puts(m, "rcu_bh:\n");
406         print_rcu_pendings(m, &rcu_bh_state);
407         return 0;
408 }
409
410 static int rcu_pending_open(struct inode *inode, struct file *file)
411 {
412         return single_open(file, show_rcu_pending, NULL);
413 }
414
415 static const struct file_operations rcu_pending_fops = {
416         .owner = THIS_MODULE,
417         .open = rcu_pending_open,
418         .read = seq_read,
419         .llseek = seq_lseek,
420         .release = single_release,
421 };
422
423 static int show_rcutorture(struct seq_file *m, void *unused)
424 {
425         seq_printf(m, "rcutorture test sequence: %lu %s\n",
426                    rcutorture_testseq >> 1,
427                    (rcutorture_testseq & 0x1) ? "(test in progress)" : "");
428         seq_printf(m, "rcutorture update version number: %lu\n",
429                    rcutorture_vernum);
430         return 0;
431 }
432
433 static int rcutorture_open(struct inode *inode, struct file *file)
434 {
435         return single_open(file, show_rcutorture, NULL);
436 }
437
438 static const struct file_operations rcutorture_fops = {
439         .owner = THIS_MODULE,
440         .open = rcutorture_open,
441         .read = seq_read,
442         .llseek = seq_lseek,
443         .release = single_release,
444 };
445
446 static struct dentry *rcudir;
447
448 static int __init rcutree_trace_init(void)
449 {
450         struct dentry *retval;
451
452         rcudir = debugfs_create_dir("rcu", NULL);
453         if (!rcudir)
454                 goto free_out;
455
456         retval = debugfs_create_file("rcudata", 0444, rcudir,
457                                                 NULL, &rcudata_fops);
458         if (!retval)
459                 goto free_out;
460
461         retval = debugfs_create_file("rcudata.csv", 0444, rcudir,
462                                                 NULL, &rcudata_csv_fops);
463         if (!retval)
464                 goto free_out;
465
466         if (rcu_boost_trace_create_file(rcudir))
467                 goto free_out;
468
469         retval = debugfs_create_file("rcugp", 0444, rcudir, NULL, &rcugp_fops);
470         if (!retval)
471                 goto free_out;
472
473         retval = debugfs_create_file("rcuhier", 0444, rcudir,
474                                                 NULL, &rcuhier_fops);
475         if (!retval)
476                 goto free_out;
477
478         retval = debugfs_create_file("rcu_pending", 0444, rcudir,
479                                                 NULL, &rcu_pending_fops);
480         if (!retval)
481                 goto free_out;
482
483         retval = debugfs_create_file("rcutorture", 0444, rcudir,
484                                                 NULL, &rcutorture_fops);
485         if (!retval)
486                 goto free_out;
487         return 0;
488 free_out:
489         debugfs_remove_recursive(rcudir);
490         return 1;
491 }
492
493 static void __exit rcutree_trace_cleanup(void)
494 {
495         debugfs_remove_recursive(rcudir);
496 }
497
498
499 module_init(rcutree_trace_init);
500 module_exit(rcutree_trace_cleanup);
501
502 MODULE_AUTHOR("Paul E. McKenney");
503 MODULE_DESCRIPTION("Read-Copy Update tracing for hierarchical implementation");
504 MODULE_LICENSE("GPL");