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