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