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
  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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