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/module.h>
  34 #include <linux/sched.h>
  35 #include <linux/atomic.h>
  36 #include <linux/bitops.h>
  37 #include <linux/export.h>
  38 #include <linux/completion.h>
  39 #include <linux/moduleparam.h>
  40 #include <linux/percpu.h>
  41 #include <linux/notifier.h>
  42 #include <linux/cpu.h>
  43 #include <linux/mutex.h>
  44 #include <linux/debugfs.h>
  45 #include <linux/seq_file.h>
  46
  47 #define RCU_TREE_NONCORE
  48 #include "rcutree.h"
  49
  50 #ifdef CONFIG_RCU_BOOST
  51
  52 static char convert_kthread_status(unsigned int kthread_status)
  53 {
  54         if (kthread_status > RCU_KTHREAD_MAX)
  55                 return '?';
  56         return "SRWOY"[kthread_status];
  57 }
  58
  59 #endif /* #ifdef CONFIG_RCU_BOOST */
  60
  61 static void print_one_rcu_data(struct seq_file *m, struct rcu_data *rdp)
  62 {
  63         if (!rdp->beenonline)
  64                 return;
  65         seq_printf(m, "%3d%cc=%lu g=%lu pq=%d pgp=%lu qp=%d",
  66                    rdp->cpu,
  67                    cpu_is_offline(rdp->cpu) ? '!' : ' ',
  68                    rdp->completed, rdp->gpnum,
  69                    rdp->passed_quiesce, rdp->passed_quiesce_gpnum,
  70                    rdp->qs_pending);
  71 #ifdef CONFIG_NO_HZ
  72         seq_printf(m, " dt=%d/%d/%d df=%lu",
  73                    atomic_read(&rdp->dynticks->dynticks),
  74                    rdp->dynticks->dynticks_nesting,
  75                    rdp->dynticks->dynticks_nmi_nesting,
  76                    rdp->dynticks_fqs);
  77 #endif /* #ifdef CONFIG_NO_HZ */
  78         seq_printf(m, " of=%lu ri=%lu", rdp->offline_fqs, rdp->resched_ipi);
  79         seq_printf(m, " ql=%ld qs=%c%c%c%c",
  80                    rdp->qlen,
  81                    ".N"[rdp->nxttail[RCU_NEXT_READY_TAIL] !=
  82                         rdp->nxttail[RCU_NEXT_TAIL]],
  83                    ".R"[rdp->nxttail[RCU_WAIT_TAIL] !=
  84                         rdp->nxttail[RCU_NEXT_READY_TAIL]],
  85                    ".W"[rdp->nxttail[RCU_DONE_TAIL] !=
  86                         rdp->nxttail[RCU_WAIT_TAIL]],
  87                    ".D"[&rdp->nxtlist != rdp->nxttail[RCU_DONE_TAIL]]);
  88 #ifdef CONFIG_RCU_BOOST
  89         seq_printf(m, " kt=%d/%c/%d ktl=%x",
  90                    per_cpu(rcu_cpu_has_work, rdp->cpu),
  91                    convert_kthread_status(per_cpu(rcu_cpu_kthread_status,
  92                                           rdp->cpu)),
  93                    per_cpu(rcu_cpu_kthread_cpu, rdp->cpu),
  94                    per_cpu(rcu_cpu_kthread_loops, rdp->cpu) & 0xffff);
  95 #endif /* #ifdef CONFIG_RCU_BOOST */
  96         seq_printf(m, " b=%ld", rdp->blimit);
  97         seq_printf(m, " ci=%lu co=%lu ca=%lu\n",
  98                    rdp->n_cbs_invoked, rdp->n_cbs_orphaned, rdp->n_cbs_adopted);
  99 }
 100
 101 #define PRINT_RCU_DATA(name, func, m) \
 102         do { \
 103                 int _p_r_d_i; \
 104                 \
 105                 for_each_possible_cpu(_p_r_d_i) \
 106                         func(m, &per_cpu(name, _p_r_d_i)); \
 107         } while (0)
 108
 109 static int show_rcudata(struct seq_file *m, void *unused)
 110 {
 111 #ifdef CONFIG_TREE_PREEMPT_RCU
 112         seq_puts(m, "rcu_preempt:\n");
 113         PRINT_RCU_DATA(rcu_preempt_data, print_one_rcu_data, m);
 114 #endif /* #ifdef CONFIG_TREE_PREEMPT_RCU */
 115         seq_puts(m, "rcu_sched:\n");
 116         PRINT_RCU_DATA(rcu_sched_data, print_one_rcu_data, m);
 117         seq_puts(m, "rcu_bh:\n");
 118         PRINT_RCU_DATA(rcu_bh_data, print_one_rcu_data, m);
 119         return 0;
 120 }
 121
 122 static int rcudata_open(struct inode *inode, struct file *file)
 123 {
 124         return single_open(file, show_rcudata, NULL);
 125 }
 126
 127 static const struct file_operations rcudata_fops = {
 128         .owner = THIS_MODULE,
 129         .open = rcudata_open,
 130         .read = seq_read,
 131         .llseek = seq_lseek,
 132         .release = single_release,
 133 };
 134
 135 static void print_one_rcu_data_csv(struct seq_file *m, struct rcu_data *rdp)
 136 {
 137         if (!rdp->beenonline)
 138                 return;
 139         seq_printf(m, "%d,%s,%lu,%lu,%d,%lu,%d",
 140                    rdp->cpu,
 141                    cpu_is_offline(rdp->cpu) ? "\"N\"" : "\"Y\"",
 142                    rdp->completed, rdp->gpnum,
 143                    rdp->passed_quiesce, rdp->passed_quiesce_gpnum,
 144                    rdp->qs_pending);
 145 #ifdef CONFIG_NO_HZ
 146         seq_printf(m, ",%d,%d,%d,%lu",
 147                    atomic_read(&rdp->dynticks->dynticks),
 148                    rdp->dynticks->dynticks_nesting,
 149                    rdp->dynticks->dynticks_nmi_nesting,
 150                    rdp->dynticks_fqs);
 151 #endif /* #ifdef CONFIG_NO_HZ */
 152         seq_printf(m, ",%lu,%lu", rdp->offline_fqs, rdp->resched_ipi);
 153         seq_printf(m, ",%ld,\"%c%c%c%c\"", rdp->qlen,
 154                    ".N"[rdp->nxttail[RCU_NEXT_READY_TAIL] !=
 155                         rdp->nxttail[RCU_NEXT_TAIL]],
 156                    ".R"[rdp->nxttail[RCU_WAIT_TAIL] !=
 157                         rdp->nxttail[RCU_NEXT_READY_TAIL]],
 158                    ".W"[rdp->nxttail[RCU_DONE_TAIL] !=
 159                         rdp->nxttail[RCU_WAIT_TAIL]],
 160                    ".D"[&rdp->nxtlist != rdp->nxttail[RCU_DONE_TAIL]]);
 161 #ifdef CONFIG_RCU_BOOST
 162         seq_printf(m, ",%d,\"%c\"",
 163                    per_cpu(rcu_cpu_has_work, rdp->cpu),
 164                    convert_kthread_status(per_cpu(rcu_cpu_kthread_status,
 165                                           rdp->cpu)));
 166 #endif /* #ifdef CONFIG_RCU_BOOST */
 167         seq_printf(m, ",%ld", rdp->blimit);
 168         seq_printf(m, ",%lu,%lu,%lu\n",
 169                    rdp->n_cbs_invoked, rdp->n_cbs_orphaned, rdp->n_cbs_adopted);
 170 }
 171
 172 static int show_rcudata_csv(struct seq_file *m, void *unused)
 173 {
 174         seq_puts(m, "\"CPU\",\"Online?\",\"c\",\"g\",\"pq\",\"pgp\",\"pq\",");
 175 #ifdef CONFIG_NO_HZ
 176         seq_puts(m, "\"dt\",\"dt nesting\",\"dt NMI nesting\",\"df\",");
 177 #endif /* #ifdef CONFIG_NO_HZ */
 178         seq_puts(m, "\"of\",\"ri\",\"ql\",\"qs\"");
 179 #ifdef CONFIG_RCU_BOOST
 180         seq_puts(m, "\"kt\",\"ktl\"");
 181 #endif /* #ifdef CONFIG_RCU_BOOST */
 182         seq_puts(m, ",\"b\",\"ci\",\"co\",\"ca\"\n");
 183 #ifdef CONFIG_TREE_PREEMPT_RCU
 184         seq_puts(m, "\"rcu_preempt:\"\n");
 185         PRINT_RCU_DATA(rcu_preempt_data, print_one_rcu_data_csv, m);
 186 #endif /* #ifdef CONFIG_TREE_PREEMPT_RCU */
 187         seq_puts(m, "\"rcu_sched:\"\n");
 188         PRINT_RCU_DATA(rcu_sched_data, print_one_rcu_data_csv, m);
 189         seq_puts(m, "\"rcu_bh:\"\n");
 190         PRINT_RCU_DATA(rcu_bh_data, print_one_rcu_data_csv, m);
 191         return 0;
 192 }
 193
 194 static int rcudata_csv_open(struct inode *inode, struct file *file)
 195 {
 196         return single_open(file, show_rcudata_csv, NULL);
 197 }
 198
 199 static const struct file_operations rcudata_csv_fops = {
 200         .owner = THIS_MODULE,
 201         .open = rcudata_csv_open,
 202         .read = seq_read,
 203         .llseek = seq_lseek,
 204         .release = single_release,
 205 };
 206
 207 #ifdef CONFIG_RCU_BOOST
 208
 209 static void print_one_rcu_node_boost(struct seq_file *m, struct rcu_node *rnp)
 210 {
 211         seq_printf(m,  "%d:%d tasks=%c%c%c%c kt=%c ntb=%lu neb=%lu nnb=%lu "
 212                    "j=%04x bt=%04x\n",
 213                    rnp->grplo, rnp->grphi,
 214                    "T."[list_empty(&rnp->blkd_tasks)],
 215                    "N."[!rnp->gp_tasks],
 216                    "E."[!rnp->exp_tasks],
 217                    "B."[!rnp->boost_tasks],
 218                    convert_kthread_status(rnp->boost_kthread_status),
 219                    rnp->n_tasks_boosted, rnp->n_exp_boosts,
 220                    rnp->n_normal_boosts,
 221                    (int)(jiffies & 0xffff),
 222                    (int)(rnp->boost_time & 0xffff));
 223         seq_printf(m, "%s: nt=%lu egt=%lu bt=%lu nb=%lu ny=%lu nos=%lu\n",
 224                    "     balk",
 225                    rnp->n_balk_blkd_tasks,
 226                    rnp->n_balk_exp_gp_tasks,
 227                    rnp->n_balk_boost_tasks,
 228                    rnp->n_balk_notblocked,
 229                    rnp->n_balk_notyet,
 230                    rnp->n_balk_nos);
 231 }
 232
 233 static int show_rcu_node_boost(struct seq_file *m, void *unused)
 234 {
 235         struct rcu_node *rnp;
 236
 237         rcu_for_each_leaf_node(&rcu_preempt_state, rnp)
 238                 print_one_rcu_node_boost(m, rnp);
 239         return 0;
 240 }
 241
 242 static int rcu_node_boost_open(struct inode *inode, struct file *file)
 243 {
 244         return single_open(file, show_rcu_node_boost, NULL);
 245 }
 246
 247 static const struct file_operations rcu_node_boost_fops = {
 248         .owner = THIS_MODULE,
 249         .open = rcu_node_boost_open,
 250         .read = seq_read,
 251         .llseek = seq_lseek,
 252         .release = single_release,
 253 };
 254
 255 /*
 256  * Create the rcuboost debugfs entry.  Standard error return.
 257  */
 258 static int rcu_boost_trace_create_file(struct dentry *rcudir)
 259 {
 260         return !debugfs_create_file("rcuboost", 0444, rcudir, NULL,
 261                                     &rcu_node_boost_fops);
 262 }
 263
 264 #else /* #ifdef CONFIG_RCU_BOOST */
 265
 266 static int rcu_boost_trace_create_file(struct dentry *rcudir)
 267 {
 268         return 0;  /* There cannot be an error if we didn't create it! */
 269 }
 270
 271 #endif /* #else #ifdef CONFIG_RCU_BOOST */
 272
 273 static void print_one_rcu_state(struct seq_file *m, struct rcu_state *rsp)
 274 {
 275         unsigned long gpnum;
 276         int level = 0;
 277         struct rcu_node *rnp;
 278
 279         gpnum = rsp->gpnum;
 280         seq_printf(m, "c=%lu g=%lu s=%d jfq=%ld j=%x "
 281                       "nfqs=%lu/nfqsng=%lu(%lu) fqlh=%lu\n",
 282                    rsp->completed, gpnum, rsp->signaled,
 283                    (long)(rsp->jiffies_force_qs - jiffies),
 284                    (int)(jiffies & 0xffff),
 285                    rsp->n_force_qs, rsp->n_force_qs_ngp,
 286                    rsp->n_force_qs - rsp->n_force_qs_ngp,
 287                    rsp->n_force_qs_lh);
 288         for (rnp = &rsp->node[0]; rnp - &rsp->node[0] < NUM_RCU_NODES; rnp++) {
 289                 if (rnp->level != level) {
 290                         seq_puts(m, "\n");
 291                         level = rnp->level;
 292                 }
 293                 seq_printf(m, "%lx/%lx %c%c>%c %d:%d ^%d    ",
 294                            rnp->qsmask, rnp->qsmaskinit,
 295                            ".G"[rnp->gp_tasks != NULL],
 296                            ".E"[rnp->exp_tasks != NULL],
 297                            ".T"[!list_empty(&rnp->blkd_tasks)],
 298                            rnp->grplo, rnp->grphi, rnp->grpnum);
 299         }
 300         seq_puts(m, "\n");
 301 }
 302
 303 static int show_rcuhier(struct seq_file *m, void *unused)
 304 {
 305 #ifdef CONFIG_TREE_PREEMPT_RCU
 306         seq_puts(m, "rcu_preempt:\n");
 307         print_one_rcu_state(m, &rcu_preempt_state);
 308 #endif /* #ifdef CONFIG_TREE_PREEMPT_RCU */
 309         seq_puts(m, "rcu_sched:\n");
 310         print_one_rcu_state(m, &rcu_sched_state);
 311         seq_puts(m, "rcu_bh:\n");
 312         print_one_rcu_state(m, &rcu_bh_state);
 313         return 0;
 314 }
 315
 316 static int rcuhier_open(struct inode *inode, struct file *file)
 317 {
 318         return single_open(file, show_rcuhier, NULL);
 319 }
 320
 321 static const struct file_operations rcuhier_fops = {
 322         .owner = THIS_MODULE,
 323         .open = rcuhier_open,
 324         .read = seq_read,
 325         .llseek = seq_lseek,
 326         .release = single_release,
 327 };
 328
 329 static void show_one_rcugp(struct seq_file *m, struct rcu_state *rsp)
 330 {
 331         unsigned long flags;
 332         unsigned long completed;
 333         unsigned long gpnum;
 334         unsigned long gpage;
 335         unsigned long gpmax;
 336         struct rcu_node *rnp = &rsp->node[0];
 337
 338         raw_spin_lock_irqsave(&rnp->lock, flags);
 339         completed = rsp->completed;
 340         gpnum = rsp->gpnum;
 341         if (rsp->completed == rsp->gpnum)
 342                 gpage = 0;
 343         else
 344                 gpage = jiffies - rsp->gp_start;
 345         gpmax = rsp->gp_max;
 346         raw_spin_unlock_irqrestore(&rnp->lock, flags);
 347         seq_printf(m, "%s: completed=%ld  gpnum=%lu  age=%ld  max=%ld\n",
 348                    rsp->name, completed, gpnum, gpage, gpmax);
 349 }
 350
 351 static int show_rcugp(struct seq_file *m, void *unused)
 352 {
 353 #ifdef CONFIG_TREE_PREEMPT_RCU
 354         show_one_rcugp(m, &rcu_preempt_state);
 355 #endif /* #ifdef CONFIG_TREE_PREEMPT_RCU */
 356         show_one_rcugp(m, &rcu_sched_state);
 357         show_one_rcugp(m, &rcu_bh_state);
 358         return 0;
 359 }
 360
 361 static int rcugp_open(struct inode *inode, struct file *file)
 362 {
 363         return single_open(file, show_rcugp, NULL);
 364 }
 365
 366 static const struct file_operations rcugp_fops = {
 367         .owner = THIS_MODULE,
 368         .open = rcugp_open,
 369         .read = seq_read,
 370         .llseek = seq_lseek,
 371         .release = single_release,
 372 };
 373
 374 static void print_one_rcu_pending(struct seq_file *m, struct rcu_data *rdp)
 375 {
 376         seq_printf(m, "%3d%cnp=%ld "
 377                    "qsp=%ld rpq=%ld cbr=%ld cng=%ld "
 378                    "gpc=%ld gps=%ld nf=%ld nn=%ld\n",
 379                    rdp->cpu,
 380                    cpu_is_offline(rdp->cpu) ? '!' : ' ',
 381                    rdp->n_rcu_pending,
 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                    rdp->n_rp_gp_completed,
 387                    rdp->n_rp_gp_started,
 388                    rdp->n_rp_need_fqs,
 389                    rdp->n_rp_need_nothing);
 390 }
 391
 392 static void print_rcu_pendings(struct seq_file *m, struct rcu_state *rsp)
 393 {
 394         int cpu;
 395         struct rcu_data *rdp;
 396
 397         for_each_possible_cpu(cpu) {
 398                 rdp = per_cpu_ptr(rsp->rda, cpu);
 399                 if (rdp->beenonline)
 400                         print_one_rcu_pending(m, rdp);
 401         }
 402 }
 403
 404 static int show_rcu_pending(struct seq_file *m, void *unused)
 405 {
 406 #ifdef CONFIG_TREE_PREEMPT_RCU
 407         seq_puts(m, "rcu_preempt:\n");
 408         print_rcu_pendings(m, &rcu_preempt_state);
 409 #endif /* #ifdef CONFIG_TREE_PREEMPT_RCU */
 410         seq_puts(m, "rcu_sched:\n");
 411         print_rcu_pendings(m, &rcu_sched_state);
 412         seq_puts(m, "rcu_bh:\n");
 413         print_rcu_pendings(m, &rcu_bh_state);
 414         return 0;
 415 }
 416
 417 static int rcu_pending_open(struct inode *inode, struct file *file)
 418 {
 419         return single_open(file, show_rcu_pending, NULL);
 420 }
 421
 422 static const struct file_operations rcu_pending_fops = {
 423         .owner = THIS_MODULE,
 424         .open = rcu_pending_open,
 425         .read = seq_read,
 426         .llseek = seq_lseek,
 427         .release = single_release,
 428 };
 429
 430 static int show_rcutorture(struct seq_file *m, void *unused)
 431 {
 432         seq_printf(m, "rcutorture test sequence: %lu %s\n",
 433                    rcutorture_testseq >> 1,
 434                    (rcutorture_testseq & 0x1) ? "(test in progress)" : "");
 435         seq_printf(m, "rcutorture update version number: %lu\n",
 436                    rcutorture_vernum);
 437         return 0;
 438 }
 439
 440 static int rcutorture_open(struct inode *inode, struct file *file)
 441 {
 442         return single_open(file, show_rcutorture, NULL);
 443 }
 444
 445 static const struct file_operations rcutorture_fops = {
 446         .owner = THIS_MODULE,
 447         .open = rcutorture_open,
 448         .read = seq_read,
 449         .llseek = seq_lseek,
 450         .release = single_release,
 451 };
 452
 453 static struct dentry *rcudir;
 454
 455 static int __init rcutree_trace_init(void)
 456 {
 457         struct dentry *retval;
 458
 459         rcudir = debugfs_create_dir("rcu", NULL);
 460         if (!rcudir)
 461                 goto free_out;
 462
 463         retval = debugfs_create_file("rcudata", 0444, rcudir,
 464                                                 NULL, &rcudata_fops);
 465         if (!retval)
 466                 goto free_out;
 467
 468         retval = debugfs_create_file("rcudata.csv", 0444, rcudir,
 469                                                 NULL, &rcudata_csv_fops);
 470         if (!retval)
 471                 goto free_out;
 472
 473         if (rcu_boost_trace_create_file(rcudir))
 474                 goto free_out;
 475
 476         retval = debugfs_create_file("rcugp", 0444, rcudir, NULL, &rcugp_fops);
 477         if (!retval)
 478                 goto free_out;
 479
 480         retval = debugfs_create_file("rcuhier", 0444, rcudir,
 481                                                 NULL, &rcuhier_fops);
 482         if (!retval)
 483                 goto free_out;
 484
 485         retval = debugfs_create_file("rcu_pending", 0444, rcudir,
 486                                                 NULL, &rcu_pending_fops);
 487         if (!retval)
 488                 goto free_out;
 489
 490         retval = debugfs_create_file("rcutorture", 0444, rcudir,
 491                                                 NULL, &rcutorture_fops);
 492         if (!retval)
 493                 goto free_out;
 494         return 0;
 495 free_out:
 496         debugfs_remove_recursive(rcudir);
 497         return 1;
 498 }
 499
 500 static void __exit rcutree_trace_cleanup(void)
 501 {
 502         debugfs_remove_recursive(rcudir);
 503 }
 504
 505
 506 module_init(rcutree_trace_init);
 507 module_exit(rcutree_trace_cleanup);
 508
 509 MODULE_AUTHOR("Paul E. McKenney");
 510 MODULE_DESCRIPTION("Read-Copy Update tracing for hierarchical implementation");
 511 MODULE_LICENSE("GPL");