linux/kernel/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
  49static int show_rcubarrier(struct seq_file *m, void *unused)
  50{
  51        struct rcu_state *rsp;
  52
  53        for_each_rcu_flavor(rsp)
  54                seq_printf(m, "%s: bcc: %d nbd: %lu\n",
  55                           rsp->name,
  56                           atomic_read(&rsp->barrier_cpu_count),
  57                           rsp->n_barrier_done);
  58        return 0;
  59}
  60
  61static int rcubarrier_open(struct inode *inode, struct file *file)
  62{
  63        return single_open(file, show_rcubarrier, NULL);
  64}
  65
  66static 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
  76static 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
  85static 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] !=
 105                        rdp->nxttail[RCU_NEXT_READY_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
 121static 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);
 128                for_each_possible_cpu(cpu)
 129                        print_one_rcu_data(m, per_cpu_ptr(rsp->rda, cpu));
 130        }
 131        return 0;
 132}
 133
 134static int rcudata_open(struct inode *inode, struct file *file)
 135{
 136        return single_open(file, show_rcudata, NULL);
 137}
 138
 139static 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
 147static 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] !=
 166                        rdp->nxttail[RCU_NEXT_READY_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
 181static 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);
 195                for_each_possible_cpu(cpu)
 196                        print_one_rcu_data_csv(m, per_cpu_ptr(rsp->rda, cpu));
 197        }
 198        return 0;
 199}
 200
 201static int rcudata_csv_open(struct inode *inode, struct file *file)
 202{
 203        return single_open(file, show_rcudata_csv, NULL);
 204}
 205
 206static 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
 216static 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
 239static 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
 248static int rcu_node_boost_open(struct inode *inode, struct file *file)
 249{
 250        return single_open(file, show_rcu_node_boost, NULL);
 251}
 252
 253static 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 */
 264static 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
 272static 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
 279static 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
 309static int show_rcuhier(struct seq_file *m, void *unused)
 310{
 311        struct rcu_state *rsp;
 312
 313        for_each_rcu_flavor(rsp)
 314                print_one_rcu_state(m, rsp);
 315        return 0;
 316}
 317
 318static int rcuhier_open(struct inode *inode, struct file *file)
 319{
 320        return single_open(file, show_rcuhier, NULL);
 321}
 322
 323static 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
 331static 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
 353static int show_rcugp(struct seq_file *m, void *unused)
 354{
 355        struct rcu_state *rsp;
 356
 357        for_each_rcu_flavor(rsp)
 358                show_one_rcugp(m, rsp);
 359        return 0;
 360}
 361
 362static int rcugp_open(struct inode *inode, struct file *file)
 363{
 364        return single_open(file, show_rcugp, NULL);
 365}
 366
 367static 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
 375static 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
 392static 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
 409static int rcu_pending_open(struct inode *inode, struct file *file)
 410{
 411        return single_open(file, show_rcu_pending, NULL);
 412}
 413
 414static 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
 422static 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",
 428                   rcutorture_vernum);
 429        return 0;
 430}
 431
 432static int rcutorture_open(struct inode *inode, struct file *file)
 433{
 434        return single_open(file, show_rcutorture, NULL);
 435}
 436
 437static 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
 445static struct dentry *rcudir;
 446
 447static 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;
 492free_out:
 493        debugfs_remove_recursive(rcudir);
 494        return 1;
 495}
 496
 497static void __exit rcutree_trace_cleanup(void)
 498{
 499        debugfs_remove_recursive(rcudir);
 500}
 501
 502
 503module_init(rcutree_trace_init);
 504module_exit(rcutree_trace_cleanup);
 505
 506MODULE_AUTHOR("Paul E. McKenney");
 507MODULE_DESCRIPTION("Read-Copy Update tracing for hierarchical implementation");
 508MODULE_LICENSE("GPL");
 509
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