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rcutree_trace.c
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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 static int show_rcubarrier(struct seq_file *m, void *unused)
50 {
51  struct rcu_state *rsp;
52 
54  seq_printf(m, "%s: bcc: %d nbd: %lu\n",
55  rsp->name,
57  rsp->n_barrier_done);
58  return 0;
59 }
60 
61 static int rcubarrier_open(struct inode *inode, struct file *file)
62 {
63  return single_open(file, show_rcubarrier, NULL);
64 }
65 
66 static const struct file_operations rcubarrier_fops = {
67  .owner = THIS_MODULE,
68  .open = rcubarrier_open,
69  .read = seq_read,
70  .llseek = seq_lseek,
71  .release = single_release,
72 };
73 
74 #ifdef CONFIG_RCU_BOOST
75 
76 static char convert_kthread_status(unsigned int kthread_status)
77 {
78  if (kthread_status > RCU_KTHREAD_MAX)
79  return '?';
80  return "SRWOY"[kthread_status];
81 }
82 
83 #endif /* #ifdef CONFIG_RCU_BOOST */
84 
85 static void print_one_rcu_data(struct seq_file *m, struct rcu_data *rdp)
86 {
87  if (!rdp->beenonline)
88  return;
89  seq_printf(m, "%3d%cc=%lu g=%lu pq=%d qp=%d",
90  rdp->cpu,
91  cpu_is_offline(rdp->cpu) ? '!' : ' ',
92  rdp->completed, rdp->gpnum,
93  rdp->passed_quiesce, rdp->qs_pending);
94  seq_printf(m, " dt=%d/%llx/%d df=%lu",
95  atomic_read(&rdp->dynticks->dynticks),
96  rdp->dynticks->dynticks_nesting,
97  rdp->dynticks->dynticks_nmi_nesting,
98  rdp->dynticks_fqs);
99  seq_printf(m, " of=%lu", rdp->offline_fqs);
100  seq_printf(m, " ql=%ld/%ld qs=%c%c%c%c",
101  rdp->qlen_lazy, rdp->qlen,
102  ".N"[rdp->nxttail[RCU_NEXT_READY_TAIL] !=
103  rdp->nxttail[RCU_NEXT_TAIL]],
104  ".R"[rdp->nxttail[RCU_WAIT_TAIL] !=
106  ".W"[rdp->nxttail[RCU_DONE_TAIL] !=
107  rdp->nxttail[RCU_WAIT_TAIL]],
108  ".D"[&rdp->nxtlist != rdp->nxttail[RCU_DONE_TAIL]]);
109 #ifdef CONFIG_RCU_BOOST
110  seq_printf(m, " kt=%d/%c ktl=%x",
111  per_cpu(rcu_cpu_has_work, rdp->cpu),
112  convert_kthread_status(per_cpu(rcu_cpu_kthread_status,
113  rdp->cpu)),
114  per_cpu(rcu_cpu_kthread_loops, rdp->cpu) & 0xffff);
115 #endif /* #ifdef CONFIG_RCU_BOOST */
116  seq_printf(m, " b=%ld", rdp->blimit);
117  seq_printf(m, " ci=%lu co=%lu ca=%lu\n",
118  rdp->n_cbs_invoked, rdp->n_cbs_orphaned, rdp->n_cbs_adopted);
119 }
120 
121 static int show_rcudata(struct seq_file *m, void *unused)
122 {
123  int cpu;
124  struct rcu_state *rsp;
125 
126  for_each_rcu_flavor(rsp) {
127  seq_printf(m, "%s:\n", rsp->name);
129  print_one_rcu_data(m, per_cpu_ptr(rsp->rda, cpu));
130  }
131  return 0;
132 }
133 
134 static int rcudata_open(struct inode *inode, struct file *file)
135 {
136  return single_open(file, show_rcudata, NULL);
137 }
138 
139 static const struct file_operations rcudata_fops = {
140  .owner = THIS_MODULE,
141  .open = rcudata_open,
142  .read = seq_read,
143  .llseek = seq_lseek,
144  .release = single_release,
145 };
146 
147 static void print_one_rcu_data_csv(struct seq_file *m, struct rcu_data *rdp)
148 {
149  if (!rdp->beenonline)
150  return;
151  seq_printf(m, "%d,%s,%lu,%lu,%d,%d",
152  rdp->cpu,
153  cpu_is_offline(rdp->cpu) ? "\"N\"" : "\"Y\"",
154  rdp->completed, rdp->gpnum,
155  rdp->passed_quiesce, rdp->qs_pending);
156  seq_printf(m, ",%d,%llx,%d,%lu",
157  atomic_read(&rdp->dynticks->dynticks),
158  rdp->dynticks->dynticks_nesting,
159  rdp->dynticks->dynticks_nmi_nesting,
160  rdp->dynticks_fqs);
161  seq_printf(m, ",%lu", rdp->offline_fqs);
162  seq_printf(m, ",%ld,%ld,\"%c%c%c%c\"", rdp->qlen_lazy, rdp->qlen,
163  ".N"[rdp->nxttail[RCU_NEXT_READY_TAIL] !=
164  rdp->nxttail[RCU_NEXT_TAIL]],
165  ".R"[rdp->nxttail[RCU_WAIT_TAIL] !=
167  ".W"[rdp->nxttail[RCU_DONE_TAIL] !=
168  rdp->nxttail[RCU_WAIT_TAIL]],
169  ".D"[&rdp->nxtlist != rdp->nxttail[RCU_DONE_TAIL]]);
170 #ifdef CONFIG_RCU_BOOST
171  seq_printf(m, ",%d,\"%c\"",
172  per_cpu(rcu_cpu_has_work, rdp->cpu),
173  convert_kthread_status(per_cpu(rcu_cpu_kthread_status,
174  rdp->cpu)));
175 #endif /* #ifdef CONFIG_RCU_BOOST */
176  seq_printf(m, ",%ld", rdp->blimit);
177  seq_printf(m, ",%lu,%lu,%lu\n",
178  rdp->n_cbs_invoked, rdp->n_cbs_orphaned, rdp->n_cbs_adopted);
179 }
180 
181 static int show_rcudata_csv(struct seq_file *m, void *unused)
182 {
183  int cpu;
184  struct rcu_state *rsp;
185 
186  seq_puts(m, "\"CPU\",\"Online?\",\"c\",\"g\",\"pq\",\"pq\",");
187  seq_puts(m, "\"dt\",\"dt nesting\",\"dt NMI nesting\",\"df\",");
188  seq_puts(m, "\"of\",\"qll\",\"ql\",\"qs\"");
189 #ifdef CONFIG_RCU_BOOST
190  seq_puts(m, "\"kt\",\"ktl\"");
191 #endif /* #ifdef CONFIG_RCU_BOOST */
192  seq_puts(m, ",\"b\",\"ci\",\"co\",\"ca\"\n");
193  for_each_rcu_flavor(rsp) {
194  seq_printf(m, "\"%s:\"\n", rsp->name);
196  print_one_rcu_data_csv(m, per_cpu_ptr(rsp->rda, cpu));
197  }
198  return 0;
199 }
200 
201 static int rcudata_csv_open(struct inode *inode, struct file *file)
202 {
203  return single_open(file, show_rcudata_csv, NULL);
204 }
205 
206 static const struct file_operations rcudata_csv_fops = {
207  .owner = THIS_MODULE,
208  .open = rcudata_csv_open,
209  .read = seq_read,
210  .llseek = seq_lseek,
211  .release = single_release,
212 };
213 
214 #ifdef CONFIG_RCU_BOOST
215 
216 static void print_one_rcu_node_boost(struct seq_file *m, struct rcu_node *rnp)
217 {
218  seq_printf(m, "%d:%d tasks=%c%c%c%c kt=%c ntb=%lu neb=%lu nnb=%lu ",
219  rnp->grplo, rnp->grphi,
220  "T."[list_empty(&rnp->blkd_tasks)],
221  "N."[!rnp->gp_tasks],
222  "E."[!rnp->exp_tasks],
223  "B."[!rnp->boost_tasks],
224  convert_kthread_status(rnp->boost_kthread_status),
225  rnp->n_tasks_boosted, rnp->n_exp_boosts,
226  rnp->n_normal_boosts);
227  seq_printf(m, "j=%04x bt=%04x\n",
228  (int)(jiffies & 0xffff),
229  (int)(rnp->boost_time & 0xffff));
230  seq_printf(m, " balk: nt=%lu egt=%lu bt=%lu nb=%lu ny=%lu nos=%lu\n",
231  rnp->n_balk_blkd_tasks,
232  rnp->n_balk_exp_gp_tasks,
233  rnp->n_balk_boost_tasks,
234  rnp->n_balk_notblocked,
235  rnp->n_balk_notyet,
236  rnp->n_balk_nos);
237 }
238 
239 static int show_rcu_node_boost(struct seq_file *m, void *unused)
240 {
241  struct rcu_node *rnp;
242 
243  rcu_for_each_leaf_node(&rcu_preempt_state, rnp)
244  print_one_rcu_node_boost(m, rnp);
245  return 0;
246 }
247 
248 static int rcu_node_boost_open(struct inode *inode, struct file *file)
249 {
250  return single_open(file, show_rcu_node_boost, NULL);
251 }
252 
253 static const struct file_operations rcu_node_boost_fops = {
254  .owner = THIS_MODULE,
255  .open = rcu_node_boost_open,
256  .read = seq_read,
257  .llseek = seq_lseek,
258  .release = single_release,
259 };
260 
261 /*
262  * Create the rcuboost debugfs entry. Standard error return.
263  */
264 static int rcu_boost_trace_create_file(struct dentry *rcudir)
265 {
266  return !debugfs_create_file("rcuboost", 0444, rcudir, NULL,
267  &rcu_node_boost_fops);
268 }
269 
270 #else /* #ifdef CONFIG_RCU_BOOST */
271 
272 static int rcu_boost_trace_create_file(struct dentry *rcudir)
273 {
274  return 0; /* There cannot be an error if we didn't create it! */
275 }
276 
277 #endif /* #else #ifdef CONFIG_RCU_BOOST */
278 
279 static void print_one_rcu_state(struct seq_file *m, struct rcu_state *rsp)
280 {
281  unsigned long gpnum;
282  int level = 0;
283  struct rcu_node *rnp;
284 
285  gpnum = rsp->gpnum;
286  seq_printf(m, "%s: c=%lu g=%lu s=%d jfq=%ld j=%x ",
287  rsp->name, rsp->completed, gpnum, rsp->fqs_state,
288  (long)(rsp->jiffies_force_qs - jiffies),
289  (int)(jiffies & 0xffff));
290  seq_printf(m, "nfqs=%lu/nfqsng=%lu(%lu) fqlh=%lu oqlen=%ld/%ld\n",
291  rsp->n_force_qs, rsp->n_force_qs_ngp,
292  rsp->n_force_qs - rsp->n_force_qs_ngp,
293  rsp->n_force_qs_lh, rsp->qlen_lazy, rsp->qlen);
294  for (rnp = &rsp->node[0]; rnp - &rsp->node[0] < rcu_num_nodes; rnp++) {
295  if (rnp->level != level) {
296  seq_puts(m, "\n");
297  level = rnp->level;
298  }
299  seq_printf(m, "%lx/%lx %c%c>%c %d:%d ^%d ",
300  rnp->qsmask, rnp->qsmaskinit,
301  ".G"[rnp->gp_tasks != NULL],
302  ".E"[rnp->exp_tasks != NULL],
303  ".T"[!list_empty(&rnp->blkd_tasks)],
304  rnp->grplo, rnp->grphi, rnp->grpnum);
305  }
306  seq_puts(m, "\n");
307 }
308 
309 static int show_rcuhier(struct seq_file *m, void *unused)
310 {
311  struct rcu_state *rsp;
312 
314  print_one_rcu_state(m, rsp);
315  return 0;
316 }
317 
318 static int rcuhier_open(struct inode *inode, struct file *file)
319 {
320  return single_open(file, show_rcuhier, NULL);
321 }
322 
323 static const struct file_operations rcuhier_fops = {
324  .owner = THIS_MODULE,
325  .open = rcuhier_open,
326  .read = seq_read,
327  .llseek = seq_lseek,
328  .release = single_release,
329 };
330 
331 static void show_one_rcugp(struct seq_file *m, struct rcu_state *rsp)
332 {
333  unsigned long flags;
334  unsigned long completed;
335  unsigned long gpnum;
336  unsigned long gpage;
337  unsigned long gpmax;
338  struct rcu_node *rnp = &rsp->node[0];
339 
340  raw_spin_lock_irqsave(&rnp->lock, flags);
341  completed = rsp->completed;
342  gpnum = rsp->gpnum;
343  if (rsp->completed == rsp->gpnum)
344  gpage = 0;
345  else
346  gpage = jiffies - rsp->gp_start;
347  gpmax = rsp->gp_max;
348  raw_spin_unlock_irqrestore(&rnp->lock, flags);
349  seq_printf(m, "%s: completed=%ld gpnum=%lu age=%ld max=%ld\n",
350  rsp->name, completed, gpnum, gpage, gpmax);
351 }
352 
353 static int show_rcugp(struct seq_file *m, void *unused)
354 {
355  struct rcu_state *rsp;
356 
358  show_one_rcugp(m, rsp);
359  return 0;
360 }
361 
362 static int rcugp_open(struct inode *inode, struct file *file)
363 {
364  return single_open(file, show_rcugp, NULL);
365 }
366 
367 static const struct file_operations rcugp_fops = {
368  .owner = THIS_MODULE,
369  .open = rcugp_open,
370  .read = seq_read,
371  .llseek = seq_lseek,
372  .release = single_release,
373 };
374 
375 static void print_one_rcu_pending(struct seq_file *m, struct rcu_data *rdp)
376 {
377  seq_printf(m, "%3d%cnp=%ld ",
378  rdp->cpu,
379  cpu_is_offline(rdp->cpu) ? '!' : ' ',
380  rdp->n_rcu_pending);
381  seq_printf(m, "qsp=%ld rpq=%ld cbr=%ld cng=%ld ",
382  rdp->n_rp_qs_pending,
383  rdp->n_rp_report_qs,
384  rdp->n_rp_cb_ready,
385  rdp->n_rp_cpu_needs_gp);
386  seq_printf(m, "gpc=%ld gps=%ld nn=%ld\n",
387  rdp->n_rp_gp_completed,
388  rdp->n_rp_gp_started,
389  rdp->n_rp_need_nothing);
390 }
391 
392 static int show_rcu_pending(struct seq_file *m, void *unused)
393 {
394  int cpu;
395  struct rcu_data *rdp;
396  struct rcu_state *rsp;
397 
398  for_each_rcu_flavor(rsp) {
399  seq_printf(m, "%s:\n", rsp->name);
400  for_each_possible_cpu(cpu) {
401  rdp = per_cpu_ptr(rsp->rda, cpu);
402  if (rdp->beenonline)
403  print_one_rcu_pending(m, rdp);
404  }
405  }
406  return 0;
407 }
408 
409 static int rcu_pending_open(struct inode *inode, struct file *file)
410 {
411  return single_open(file, show_rcu_pending, NULL);
412 }
413 
414 static const struct file_operations rcu_pending_fops = {
415  .owner = THIS_MODULE,
416  .open = rcu_pending_open,
417  .read = seq_read,
418  .llseek = seq_lseek,
419  .release = single_release,
420 };
421 
422 static int show_rcutorture(struct seq_file *m, void *unused)
423 {
424  seq_printf(m, "rcutorture test sequence: %lu %s\n",
425  rcutorture_testseq >> 1,
426  (rcutorture_testseq & 0x1) ? "(test in progress)" : "");
427  seq_printf(m, "rcutorture update version number: %lu\n",
429  return 0;
430 }
431 
432 static int rcutorture_open(struct inode *inode, struct file *file)
433 {
434  return single_open(file, show_rcutorture, NULL);
435 }
436 
437 static const struct file_operations rcutorture_fops = {
438  .owner = THIS_MODULE,
439  .open = rcutorture_open,
440  .read = seq_read,
441  .llseek = seq_lseek,
442  .release = single_release,
443 };
444 
445 static struct dentry *rcudir;
446 
447 static int __init rcutree_trace_init(void)
448 {
449  struct dentry *retval;
450 
451  rcudir = debugfs_create_dir("rcu", NULL);
452  if (!rcudir)
453  goto free_out;
454 
455  retval = debugfs_create_file("rcubarrier", 0444, rcudir,
456  NULL, &rcubarrier_fops);
457  if (!retval)
458  goto free_out;
459 
460  retval = debugfs_create_file("rcudata", 0444, rcudir,
461  NULL, &rcudata_fops);
462  if (!retval)
463  goto free_out;
464 
465  retval = debugfs_create_file("rcudata.csv", 0444, rcudir,
466  NULL, &rcudata_csv_fops);
467  if (!retval)
468  goto free_out;
469 
470  if (rcu_boost_trace_create_file(rcudir))
471  goto free_out;
472 
473  retval = debugfs_create_file("rcugp", 0444, rcudir, NULL, &rcugp_fops);
474  if (!retval)
475  goto free_out;
476 
477  retval = debugfs_create_file("rcuhier", 0444, rcudir,
478  NULL, &rcuhier_fops);
479  if (!retval)
480  goto free_out;
481 
482  retval = debugfs_create_file("rcu_pending", 0444, rcudir,
483  NULL, &rcu_pending_fops);
484  if (!retval)
485  goto free_out;
486 
487  retval = debugfs_create_file("rcutorture", 0444, rcudir,
488  NULL, &rcutorture_fops);
489  if (!retval)
490  goto free_out;
491  return 0;
492 free_out:
493  debugfs_remove_recursive(rcudir);
494  return 1;
495 }
496 
497 static void __exit rcutree_trace_cleanup(void)
498 {
499  debugfs_remove_recursive(rcudir);
500 }
501 
502 
503 module_init(rcutree_trace_init);
504 module_exit(rcutree_trace_cleanup);
505 
506 MODULE_AUTHOR("Paul E. McKenney");
507 MODULE_DESCRIPTION("Read-Copy Update tracing for hierarchical implementation");
508 MODULE_LICENSE("GPL");