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 <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
  51 DECLARE_PER_CPU(unsigned int, rcu_cpu_kthread_status);
  52 DECLARE_PER_CPU(unsigned int, rcu_cpu_kthread_cpu);
  53 DECLARE_PER_CPU(unsigned int, rcu_cpu_kthread_loops);
  54 DECLARE_PER_CPU(char, rcu_cpu_has_work);
  55
  56 static 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
  65 static 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
 113 static 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
 126 static int rcudata_open(struct inode *inode, struct file *file)
 127 {
 128         return single_open(file, show_rcudata, NULL);
 129 }
 130
 131 static 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
 139 static 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
 176 static 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
 198 static int rcudata_csv_open(struct inode *inode, struct file *file)
 199 {
 200         return single_open(file, show_rcudata_csv, NULL);
 201 }
 202
 203 static 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
 213 static 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
 237 static 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
 246 static int rcu_node_boost_open(struct inode *inode, struct file *file)
 247 {
 248         return single_open(file, show_rcu_node_boost, NULL);
 249 }
 250
 251 static 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  */
 262 static 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
 270 static 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
 277 static 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
 307 static 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
 320 static int rcuhier_open(struct inode *inode, struct file *file)
 321 {
 322         return single_open(file, show_rcuhier, NULL);
 323 }
 324
 325 static 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
 333 static 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
 355 static 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
 365 static int rcugp_open(struct inode *inode, struct file *file)
 366 {
 367         return single_open(file, show_rcugp, NULL);
 368 }
 369
 370 static 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
 378 static 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
 396 static 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
 408 static 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
 421 static int rcu_pending_open(struct inode *inode, struct file *file)
 422 {
 423         return single_open(file, show_rcu_pending, NULL);
 424 }
 425
 426 static 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
 434 static 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
 444 static int rcutorture_open(struct inode *inode, struct file *file)
 445 {
 446         return single_open(file, show_rcutorture, NULL);
 447 }
 448
 449 static 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
 457 static struct dentry *rcudir;
 458
 459 static 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;
 499 free_out:
 500         debugfs_remove_recursive(rcudir);
 501         return 1;
 502 }
 503
 504 static void __exit rcutree_trace_cleanup(void)
 505 {
 506         debugfs_remove_recursive(rcudir);
 507 }
 508
 509
 510 module_init(rcutree_trace_init);
 511 module_exit(rcutree_trace_cleanup);
 512
 513 MODULE_AUTHOR("Paul E. McKenney");
 514 MODULE_DESCRIPTION("Read-Copy Update tracing for hierarchical implementation");
 515 MODULE_LICENSE("GPL");