Root/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 <asm/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
51DECLARE_PER_CPU(unsigned int, rcu_cpu_kthread_status);
52DECLARE_PER_CPU(unsigned int, rcu_cpu_kthread_cpu);
53DECLARE_PER_CPU(unsigned int, rcu_cpu_kthread_loops);
54DECLARE_PER_CPU(char, rcu_cpu_has_work);
55
56static char convert_kthread_status(unsigned int kthread_status)
57{
58    if (kthread_status > RCU_KTHREAD_MAX)
59        return '?';
60    return "SRWOY"[kthread_status];
61}
62
63#endif /* #ifdef CONFIG_RCU_BOOST */
64
65static void print_one_rcu_data(struct seq_file *m, struct rcu_data *rdp)
66{
67    if (!rdp->beenonline)
68        return;
69    seq_printf(m, "%3d%cc=%lu g=%lu pq=%d pqc=%lu qp=%d",
70           rdp->cpu,
71           cpu_is_offline(rdp->cpu) ? '!' : ' ',
72           rdp->completed, rdp->gpnum,
73           rdp->passed_quiesc, rdp->passed_quiesc_completed,
74           rdp->qs_pending);
75#ifdef CONFIG_NO_HZ
76    seq_printf(m, " dt=%d/%d/%d df=%lu",
77           atomic_read(&rdp->dynticks->dynticks),
78           rdp->dynticks->dynticks_nesting,
79           rdp->dynticks->dynticks_nmi_nesting,
80           rdp->dynticks_fqs);
81#endif /* #ifdef CONFIG_NO_HZ */
82    seq_printf(m, " of=%lu ri=%lu", rdp->offline_fqs, rdp->resched_ipi);
83    seq_printf(m, " ql=%ld qs=%c%c%c%c",
84           rdp->qlen,
85           ".N"[rdp->nxttail[RCU_NEXT_READY_TAIL] !=
86            rdp->nxttail[RCU_NEXT_TAIL]],
87           ".R"[rdp->nxttail[RCU_WAIT_TAIL] !=
88            rdp->nxttail[RCU_NEXT_READY_TAIL]],
89           ".W"[rdp->nxttail[RCU_DONE_TAIL] !=
90            rdp->nxttail[RCU_WAIT_TAIL]],
91           ".D"[&rdp->nxtlist != rdp->nxttail[RCU_DONE_TAIL]]);
92#ifdef CONFIG_RCU_BOOST
93    seq_printf(m, " kt=%d/%c/%d ktl=%x",
94           per_cpu(rcu_cpu_has_work, rdp->cpu),
95           convert_kthread_status(per_cpu(rcu_cpu_kthread_status,
96                      rdp->cpu)),
97           per_cpu(rcu_cpu_kthread_cpu, rdp->cpu),
98           per_cpu(rcu_cpu_kthread_loops, rdp->cpu) & 0xffff);
99#endif /* #ifdef CONFIG_RCU_BOOST */
100    seq_printf(m, " b=%ld", rdp->blimit);
101    seq_printf(m, " ci=%lu co=%lu ca=%lu\n",
102           rdp->n_cbs_invoked, rdp->n_cbs_orphaned, rdp->n_cbs_adopted);
103}
104
105#define PRINT_RCU_DATA(name, func, m) \
106    do { \
107        int _p_r_d_i; \
108        \
109        for_each_possible_cpu(_p_r_d_i) \
110            func(m, &per_cpu(name, _p_r_d_i)); \
111    } while (0)
112
113static int show_rcudata(struct seq_file *m, void *unused)
114{
115#ifdef CONFIG_TREE_PREEMPT_RCU
116    seq_puts(m, "rcu_preempt:\n");
117    PRINT_RCU_DATA(rcu_preempt_data, print_one_rcu_data, m);
118#endif /* #ifdef CONFIG_TREE_PREEMPT_RCU */
119    seq_puts(m, "rcu_sched:\n");
120    PRINT_RCU_DATA(rcu_sched_data, print_one_rcu_data, m);
121    seq_puts(m, "rcu_bh:\n");
122    PRINT_RCU_DATA(rcu_bh_data, print_one_rcu_data, m);
123    return 0;
124}
125
126static int rcudata_open(struct inode *inode, struct file *file)
127{
128    return single_open(file, show_rcudata, NULL);
129}
130
131static const struct file_operations rcudata_fops = {
132    .owner = THIS_MODULE,
133    .open = rcudata_open,
134    .read = seq_read,
135    .llseek = seq_lseek,
136    .release = single_release,
137};
138
139static void print_one_rcu_data_csv(struct seq_file *m, struct rcu_data *rdp)
140{
141    if (!rdp->beenonline)
142        return;
143    seq_printf(m, "%d,%s,%lu,%lu,%d,%lu,%d",
144           rdp->cpu,
145           cpu_is_offline(rdp->cpu) ? "\"N\"" : "\"Y\"",
146           rdp->completed, rdp->gpnum,
147           rdp->passed_quiesc, rdp->passed_quiesc_completed,
148           rdp->qs_pending);
149#ifdef CONFIG_NO_HZ
150    seq_printf(m, ",%d,%d,%d,%lu",
151           atomic_read(&rdp->dynticks->dynticks),
152           rdp->dynticks->dynticks_nesting,
153           rdp->dynticks->dynticks_nmi_nesting,
154           rdp->dynticks_fqs);
155#endif /* #ifdef CONFIG_NO_HZ */
156    seq_printf(m, ",%lu,%lu", rdp->offline_fqs, rdp->resched_ipi);
157    seq_printf(m, ",%ld,\"%c%c%c%c\"", rdp->qlen,
158           ".N"[rdp->nxttail[RCU_NEXT_READY_TAIL] !=
159            rdp->nxttail[RCU_NEXT_TAIL]],
160           ".R"[rdp->nxttail[RCU_WAIT_TAIL] !=
161            rdp->nxttail[RCU_NEXT_READY_TAIL]],
162           ".W"[rdp->nxttail[RCU_DONE_TAIL] !=
163            rdp->nxttail[RCU_WAIT_TAIL]],
164           ".D"[&rdp->nxtlist != rdp->nxttail[RCU_DONE_TAIL]]);
165#ifdef CONFIG_RCU_BOOST
166    seq_printf(m, ",%d,\"%c\"",
167           per_cpu(rcu_cpu_has_work, rdp->cpu),
168           convert_kthread_status(per_cpu(rcu_cpu_kthread_status,
169                      rdp->cpu)));
170#endif /* #ifdef CONFIG_RCU_BOOST */
171    seq_printf(m, ",%ld", rdp->blimit);
172    seq_printf(m, ",%lu,%lu,%lu\n",
173           rdp->n_cbs_invoked, rdp->n_cbs_orphaned, rdp->n_cbs_adopted);
174}
175
176static int show_rcudata_csv(struct seq_file *m, void *unused)
177{
178    seq_puts(m, "\"CPU\",\"Online?\",\"c\",\"g\",\"pq\",\"pqc\",\"pq\",");
179#ifdef CONFIG_NO_HZ
180    seq_puts(m, "\"dt\",\"dt nesting\",\"dt NMI nesting\",\"df\",");
181#endif /* #ifdef CONFIG_NO_HZ */
182    seq_puts(m, "\"of\",\"ri\",\"ql\",\"qs\"");
183#ifdef CONFIG_RCU_BOOST
184    seq_puts(m, "\"kt\",\"ktl\"");
185#endif /* #ifdef CONFIG_RCU_BOOST */
186    seq_puts(m, ",\"b\",\"ci\",\"co\",\"ca\"\n");
187#ifdef CONFIG_TREE_PREEMPT_RCU
188    seq_puts(m, "\"rcu_preempt:\"\n");
189    PRINT_RCU_DATA(rcu_preempt_data, print_one_rcu_data_csv, m);
190#endif /* #ifdef CONFIG_TREE_PREEMPT_RCU */
191    seq_puts(m, "\"rcu_sched:\"\n");
192    PRINT_RCU_DATA(rcu_sched_data, print_one_rcu_data_csv, m);
193    seq_puts(m, "\"rcu_bh:\"\n");
194    PRINT_RCU_DATA(rcu_bh_data, print_one_rcu_data_csv, m);
195    return 0;
196}
197
198static int rcudata_csv_open(struct inode *inode, struct file *file)
199{
200    return single_open(file, show_rcudata_csv, NULL);
201}
202
203static const struct file_operations rcudata_csv_fops = {
204    .owner = THIS_MODULE,
205    .open = rcudata_csv_open,
206    .read = seq_read,
207    .llseek = seq_lseek,
208    .release = single_release,
209};
210
211#ifdef CONFIG_RCU_BOOST
212
213static void print_one_rcu_node_boost(struct seq_file *m, struct rcu_node *rnp)
214{
215    seq_printf(m, "%d:%d tasks=%c%c%c%c kt=%c ntb=%lu neb=%lu nnb=%lu "
216           "j=%04x bt=%04x\n",
217           rnp->grplo, rnp->grphi,
218           "T."[list_empty(&rnp->blkd_tasks)],
219           "N."[!rnp->gp_tasks],
220           "E."[!rnp->exp_tasks],
221           "B."[!rnp->boost_tasks],
222           convert_kthread_status(rnp->boost_kthread_status),
223           rnp->n_tasks_boosted, rnp->n_exp_boosts,
224           rnp->n_normal_boosts,
225           (int)(jiffies & 0xffff),
226           (int)(rnp->boost_time & 0xffff));
227    seq_printf(m, "%s: nt=%lu egt=%lu bt=%lu nb=%lu ny=%lu nos=%lu\n",
228           " balk",
229           rnp->n_balk_blkd_tasks,
230           rnp->n_balk_exp_gp_tasks,
231           rnp->n_balk_boost_tasks,
232           rnp->n_balk_notblocked,
233           rnp->n_balk_notyet,
234           rnp->n_balk_nos);
235}
236
237static int show_rcu_node_boost(struct seq_file *m, void *unused)
238{
239    struct rcu_node *rnp;
240
241    rcu_for_each_leaf_node(&rcu_preempt_state, rnp)
242        print_one_rcu_node_boost(m, rnp);
243    return 0;
244}
245
246static int rcu_node_boost_open(struct inode *inode, struct file *file)
247{
248    return single_open(file, show_rcu_node_boost, NULL);
249}
250
251static const struct file_operations rcu_node_boost_fops = {
252    .owner = THIS_MODULE,
253    .open = rcu_node_boost_open,
254    .read = seq_read,
255    .llseek = seq_lseek,
256    .release = single_release,
257};
258
259/*
260 * Create the rcuboost debugfs entry. Standard error return.
261 */
262static int rcu_boost_trace_create_file(struct dentry *rcudir)
263{
264    return !debugfs_create_file("rcuboost", 0444, rcudir, NULL,
265                    &rcu_node_boost_fops);
266}
267
268#else /* #ifdef CONFIG_RCU_BOOST */
269
270static int rcu_boost_trace_create_file(struct dentry *rcudir)
271{
272    return 0; /* There cannot be an error if we didn't create it! */
273}
274
275#endif /* #else #ifdef CONFIG_RCU_BOOST */
276
277static void print_one_rcu_state(struct seq_file *m, struct rcu_state *rsp)
278{
279    unsigned long gpnum;
280    int level = 0;
281    struct rcu_node *rnp;
282
283    gpnum = rsp->gpnum;
284    seq_printf(m, "c=%lu g=%lu s=%d jfq=%ld j=%x "
285              "nfqs=%lu/nfqsng=%lu(%lu) fqlh=%lu\n",
286           rsp->completed, gpnum, rsp->signaled,
287           (long)(rsp->jiffies_force_qs - jiffies),
288           (int)(jiffies & 0xffff),
289           rsp->n_force_qs, rsp->n_force_qs_ngp,
290           rsp->n_force_qs - rsp->n_force_qs_ngp,
291           rsp->n_force_qs_lh);
292    for (rnp = &rsp->node[0]; rnp - &rsp->node[0] < NUM_RCU_NODES; rnp++) {
293        if (rnp->level != level) {
294            seq_puts(m, "\n");
295            level = rnp->level;
296        }
297        seq_printf(m, "%lx/%lx %c%c>%c %d:%d ^%d ",
298               rnp->qsmask, rnp->qsmaskinit,
299               ".G"[rnp->gp_tasks != NULL],
300               ".E"[rnp->exp_tasks != NULL],
301               ".T"[!list_empty(&rnp->blkd_tasks)],
302               rnp->grplo, rnp->grphi, rnp->grpnum);
303    }
304    seq_puts(m, "\n");
305}
306
307static int show_rcuhier(struct seq_file *m, void *unused)
308{
309#ifdef CONFIG_TREE_PREEMPT_RCU
310    seq_puts(m, "rcu_preempt:\n");
311    print_one_rcu_state(m, &rcu_preempt_state);
312#endif /* #ifdef CONFIG_TREE_PREEMPT_RCU */
313    seq_puts(m, "rcu_sched:\n");
314    print_one_rcu_state(m, &rcu_sched_state);
315    seq_puts(m, "rcu_bh:\n");
316    print_one_rcu_state(m, &rcu_bh_state);
317    return 0;
318}
319
320static int rcuhier_open(struct inode *inode, struct file *file)
321{
322    return single_open(file, show_rcuhier, NULL);
323}
324
325static const struct file_operations rcuhier_fops = {
326    .owner = THIS_MODULE,
327    .open = rcuhier_open,
328    .read = seq_read,
329    .llseek = seq_lseek,
330    .release = single_release,
331};
332
333static void show_one_rcugp(struct seq_file *m, struct rcu_state *rsp)
334{
335    unsigned long flags;
336    unsigned long completed;
337    unsigned long gpnum;
338    unsigned long gpage;
339    unsigned long gpmax;
340    struct rcu_node *rnp = &rsp->node[0];
341
342    raw_spin_lock_irqsave(&rnp->lock, flags);
343    completed = rsp->completed;
344    gpnum = rsp->gpnum;
345    if (rsp->completed == rsp->gpnum)
346        gpage = 0;
347    else
348        gpage = jiffies - rsp->gp_start;
349    gpmax = rsp->gp_max;
350    raw_spin_unlock_irqrestore(&rnp->lock, flags);
351    seq_printf(m, "%s: completed=%ld gpnum=%lu age=%ld max=%ld\n",
352           rsp->name, completed, gpnum, gpage, gpmax);
353}
354
355static int show_rcugp(struct seq_file *m, void *unused)
356{
357#ifdef CONFIG_TREE_PREEMPT_RCU
358    show_one_rcugp(m, &rcu_preempt_state);
359#endif /* #ifdef CONFIG_TREE_PREEMPT_RCU */
360    show_one_rcugp(m, &rcu_sched_state);
361    show_one_rcugp(m, &rcu_bh_state);
362    return 0;
363}
364
365static int rcugp_open(struct inode *inode, struct file *file)
366{
367    return single_open(file, show_rcugp, NULL);
368}
369
370static const struct file_operations rcugp_fops = {
371    .owner = THIS_MODULE,
372    .open = rcugp_open,
373    .read = seq_read,
374    .llseek = seq_lseek,
375    .release = single_release,
376};
377
378static void print_one_rcu_pending(struct seq_file *m, struct rcu_data *rdp)
379{
380    seq_printf(m, "%3d%cnp=%ld "
381           "qsp=%ld rpq=%ld cbr=%ld cng=%ld "
382           "gpc=%ld gps=%ld nf=%ld nn=%ld\n",
383           rdp->cpu,
384           cpu_is_offline(rdp->cpu) ? '!' : ' ',
385           rdp->n_rcu_pending,
386           rdp->n_rp_qs_pending,
387           rdp->n_rp_report_qs,
388           rdp->n_rp_cb_ready,
389           rdp->n_rp_cpu_needs_gp,
390           rdp->n_rp_gp_completed,
391           rdp->n_rp_gp_started,
392           rdp->n_rp_need_fqs,
393           rdp->n_rp_need_nothing);
394}
395
396static void print_rcu_pendings(struct seq_file *m, struct rcu_state *rsp)
397{
398    int cpu;
399    struct rcu_data *rdp;
400
401    for_each_possible_cpu(cpu) {
402        rdp = per_cpu_ptr(rsp->rda, cpu);
403        if (rdp->beenonline)
404            print_one_rcu_pending(m, rdp);
405    }
406}
407
408static int show_rcu_pending(struct seq_file *m, void *unused)
409{
410#ifdef CONFIG_TREE_PREEMPT_RCU
411    seq_puts(m, "rcu_preempt:\n");
412    print_rcu_pendings(m, &rcu_preempt_state);
413#endif /* #ifdef CONFIG_TREE_PREEMPT_RCU */
414    seq_puts(m, "rcu_sched:\n");
415    print_rcu_pendings(m, &rcu_sched_state);
416    seq_puts(m, "rcu_bh:\n");
417    print_rcu_pendings(m, &rcu_bh_state);
418    return 0;
419}
420
421static int rcu_pending_open(struct inode *inode, struct file *file)
422{
423    return single_open(file, show_rcu_pending, NULL);
424}
425
426static const struct file_operations rcu_pending_fops = {
427    .owner = THIS_MODULE,
428    .open = rcu_pending_open,
429    .read = seq_read,
430    .llseek = seq_lseek,
431    .release = single_release,
432};
433
434static int show_rcutorture(struct seq_file *m, void *unused)
435{
436    seq_printf(m, "rcutorture test sequence: %lu %s\n",
437           rcutorture_testseq >> 1,
438           (rcutorture_testseq & 0x1) ? "(test in progress)" : "");
439    seq_printf(m, "rcutorture update version number: %lu\n",
440           rcutorture_vernum);
441    return 0;
442}
443
444static int rcutorture_open(struct inode *inode, struct file *file)
445{
446    return single_open(file, show_rcutorture, NULL);
447}
448
449static const struct file_operations rcutorture_fops = {
450    .owner = THIS_MODULE,
451    .open = rcutorture_open,
452    .read = seq_read,
453    .llseek = seq_lseek,
454    .release = single_release,
455};
456
457static struct dentry *rcudir;
458
459static int __init rcutree_trace_init(void)
460{
461    struct dentry *retval;
462
463    rcudir = debugfs_create_dir("rcu", NULL);
464    if (!rcudir)
465        goto free_out;
466
467    retval = debugfs_create_file("rcudata", 0444, rcudir,
468                        NULL, &rcudata_fops);
469    if (!retval)
470        goto free_out;
471
472    retval = debugfs_create_file("rcudata.csv", 0444, rcudir,
473                        NULL, &rcudata_csv_fops);
474    if (!retval)
475        goto free_out;
476
477    if (rcu_boost_trace_create_file(rcudir))
478        goto free_out;
479
480    retval = debugfs_create_file("rcugp", 0444, rcudir, NULL, &rcugp_fops);
481    if (!retval)
482        goto free_out;
483
484    retval = debugfs_create_file("rcuhier", 0444, rcudir,
485                        NULL, &rcuhier_fops);
486    if (!retval)
487        goto free_out;
488
489    retval = debugfs_create_file("rcu_pending", 0444, rcudir,
490                        NULL, &rcu_pending_fops);
491    if (!retval)
492        goto free_out;
493
494    retval = debugfs_create_file("rcutorture", 0444, rcudir,
495                        NULL, &rcutorture_fops);
496    if (!retval)
497        goto free_out;
498    return 0;
499free_out:
500    debugfs_remove_recursive(rcudir);
501    return 1;
502}
503
504static void __exit rcutree_trace_cleanup(void)
505{
506    debugfs_remove_recursive(rcudir);
507}
508
509
510module_init(rcutree_trace_init);
511module_exit(rcutree_trace_cleanup);
512
513MODULE_AUTHOR("Paul E. McKenney");
514MODULE_DESCRIPTION("Read-Copy Update tracing for hierarchical implementation");
515MODULE_LICENSE("GPL");
516

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