kernel/rcu/tree_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, you can access it online at
  16  * http://www.gnu.org/licenses/gpl-2.0.html.
  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 "tree.h"
  48
  49 DECLARE_PER_CPU_SHARED_ALIGNED(unsigned long, rcu_qs_ctr);
  50
  51 static int r_open(struct inode *inode, struct file *file,
  52                                         const struct seq_operations *op)
  53 {
  54         int ret = seq_open(file, op);
  55         if (!ret) {
  56                 struct seq_file *m = (struct seq_file *)file->private_data;
  57                 m->private = inode->i_private;
  58         }
  59         return ret;
  60 }
  61
  62 static void *r_start(struct seq_file *m, loff_t *pos)
  63 {
  64         struct rcu_state *rsp = (struct rcu_state *)m->private;
  65         *pos = cpumask_next(*pos - 1, cpu_possible_mask);
  66         if ((*pos) < nr_cpu_ids)
  67                 return per_cpu_ptr(rsp->rda, *pos);
  68         return NULL;
  69 }
  70
  71 static void *r_next(struct seq_file *m, void *v, loff_t *pos)
  72 {
  73         (*pos)++;
  74         return r_start(m, pos);
  75 }
  76
  77 static void r_stop(struct seq_file *m, void *v)
  78 {
  79 }
  80
  81 static int show_rcubarrier(struct seq_file *m, void *v)
  82 {
  83         struct rcu_state *rsp = (struct rcu_state *)m->private;
  84         seq_printf(m, "bcc: %d bseq: %lu\n",
  85                    atomic_read(&rsp->barrier_cpu_count),
  86                    rsp->barrier_sequence);
  87         return 0;
  88 }
  89
  90 static int rcubarrier_open(struct inode *inode, struct file *file)
  91 {
  92         return single_open(file, show_rcubarrier, inode->i_private);
  93 }
  94
  95 static const struct file_operations rcubarrier_fops = {
  96         .owner = THIS_MODULE,
  97         .open = rcubarrier_open,
  98         .read = seq_read,
  99         .llseek = no_llseek,
 100         .release = single_release,
 101 };
 102
 103 #ifdef CONFIG_RCU_BOOST
 104
 105 static char convert_kthread_status(unsigned int kthread_status)
 106 {
 107         if (kthread_status > RCU_KTHREAD_MAX)
 108                 return '?';
 109         return "SRWOY"[kthread_status];
 110 }
 111
 112 #endif /* #ifdef CONFIG_RCU_BOOST */
 113
 114 static void print_one_rcu_data(struct seq_file *m, struct rcu_data *rdp)
 115 {
 116         long ql, qll;
 117
 118         if (!rdp->beenonline)
 119                 return;
 120         seq_printf(m, "%3d%cc=%ld g=%ld cnq=%d/%d:%d",
 121                    rdp->cpu,
 122                    cpu_is_offline(rdp->cpu) ? '!' : ' ',
 123                    ulong2long(rdp->completed), ulong2long(rdp->gpnum),
 124                    rdp->cpu_no_qs.b.norm,
 125                    rdp->rcu_qs_ctr_snap == per_cpu(rcu_qs_ctr, rdp->cpu),
 126                    rdp->core_needs_qs);
 127         seq_printf(m, " dt=%d/%llx/%d df=%lu",
 128                    atomic_read(&rdp->dynticks->dynticks),
 129                    rdp->dynticks->dynticks_nesting,
 130                    rdp->dynticks->dynticks_nmi_nesting,
 131                    rdp->dynticks_fqs);
 132         seq_printf(m, " of=%lu", rdp->offline_fqs);
 133         rcu_nocb_q_lengths(rdp, &ql, &qll);
 134         qll += rdp->qlen_lazy;
 135         ql += rdp->qlen;
 136         seq_printf(m, " ql=%ld/%ld qs=%c%c%c%c",
 137                    qll, ql,
 138                    ".N"[rdp->nxttail[RCU_NEXT_READY_TAIL] !=
 139                         rdp->nxttail[RCU_NEXT_TAIL]],
 140                    ".R"[rdp->nxttail[RCU_WAIT_TAIL] !=
 141                         rdp->nxttail[RCU_NEXT_READY_TAIL]],
 142                    ".W"[rdp->nxttail[RCU_DONE_TAIL] !=
 143                         rdp->nxttail[RCU_WAIT_TAIL]],
 144                    ".D"[&rdp->nxtlist != rdp->nxttail[RCU_DONE_TAIL]]);
 145 #ifdef CONFIG_RCU_BOOST
 146         seq_printf(m, " kt=%d/%c ktl=%x",
 147                    per_cpu(rcu_cpu_has_work, rdp->cpu),
 148                    convert_kthread_status(per_cpu(rcu_cpu_kthread_status,
 149                                           rdp->cpu)),
 150                    per_cpu(rcu_cpu_kthread_loops, rdp->cpu) & 0xffff);
 151 #endif /* #ifdef CONFIG_RCU_BOOST */
 152         seq_printf(m, " b=%ld", rdp->blimit);
 153         seq_printf(m, " ci=%lu nci=%lu co=%lu ca=%lu\n",
 154                    rdp->n_cbs_invoked, rdp->n_nocbs_invoked,
 155                    rdp->n_cbs_orphaned, rdp->n_cbs_adopted);
 156 }
 157
 158 static int show_rcudata(struct seq_file *m, void *v)
 159 {
 160         print_one_rcu_data(m, (struct rcu_data *)v);
 161         return 0;
 162 }
 163
 164 static const struct seq_operations rcudate_op = {
 165         .start = r_start,
 166         .next  = r_next,
 167         .stop  = r_stop,
 168         .show  = show_rcudata,
 169 };
 170
 171 static int rcudata_open(struct inode *inode, struct file *file)
 172 {
 173         return r_open(inode, file, &rcudate_op);
 174 }
 175
 176 static const struct file_operations rcudata_fops = {
 177         .owner = THIS_MODULE,
 178         .open = rcudata_open,
 179         .read = seq_read,
 180         .llseek = no_llseek,
 181         .release = seq_release,
 182 };
 183
 184 static int show_rcuexp(struct seq_file *m, void *v)
 185 {
 186         struct rcu_state *rsp = (struct rcu_state *)m->private;
 187
 188         seq_printf(m, "s=%lu wd0=%lu wd1=%lu wd2=%lu wd3=%lu n=%lu enq=%d sc=%lu\n",
 189                    rsp->expedited_sequence,
 190                    atomic_long_read(&rsp->expedited_workdone0),
 191                    atomic_long_read(&rsp->expedited_workdone1),
 192                    atomic_long_read(&rsp->expedited_workdone2),
 193                    atomic_long_read(&rsp->expedited_workdone3),
 194                    atomic_long_read(&rsp->expedited_normal),
 195                    atomic_read(&rsp->expedited_need_qs),
 196                    rsp->expedited_sequence / 2);
 197         return 0;
 198 }
 199
 200 static int rcuexp_open(struct inode *inode, struct file *file)
 201 {
 202         return single_open(file, show_rcuexp, inode->i_private);
 203 }
 204
 205 static const struct file_operations rcuexp_fops = {
 206         .owner = THIS_MODULE,
 207         .open = rcuexp_open,
 208         .read = seq_read,
 209         .llseek = no_llseek,
 210         .release = single_release,
 211 };
 212
 213 #ifdef CONFIG_RCU_BOOST
 214
 215 static void print_one_rcu_node_boost(struct seq_file *m, struct rcu_node *rnp)
 216 {
 217         seq_printf(m, "%d:%d tasks=%c%c%c%c kt=%c ntb=%lu neb=%lu nnb=%lu ",
 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         seq_printf(m, "j=%04x bt=%04x\n",
 227                    (int)(jiffies & 0xffff),
 228                    (int)(rnp->boost_time & 0xffff));
 229         seq_printf(m, "    balk: nt=%lu egt=%lu bt=%lu nb=%lu ny=%lu nos=%lu\n",
 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 = no_llseek,
 257         .release = single_release,
 258 };
 259
 260 #endif /* #ifdef CONFIG_RCU_BOOST */
 261
 262 static void print_one_rcu_state(struct seq_file *m, struct rcu_state *rsp)
 263 {
 264         unsigned long gpnum;
 265         int level = 0;
 266         struct rcu_node *rnp;
 267
 268         gpnum = rsp->gpnum;
 269         seq_printf(m, "c=%ld g=%ld s=%d jfq=%ld j=%x ",
 270                    ulong2long(rsp->completed), ulong2long(gpnum),
 271                    rsp->gp_state,
 272                    (long)(rsp->jiffies_force_qs - jiffies),
 273                    (int)(jiffies & 0xffff));
 274         seq_printf(m, "nfqs=%lu/nfqsng=%lu(%lu) fqlh=%lu oqlen=%ld/%ld\n",
 275                    rsp->n_force_qs, rsp->n_force_qs_ngp,
 276                    rsp->n_force_qs - rsp->n_force_qs_ngp,
 277                    READ_ONCE(rsp->n_force_qs_lh), rsp->qlen_lazy, rsp->qlen);
 278         for (rnp = &rsp->node[0]; rnp - &rsp->node[0] < rcu_num_nodes; rnp++) {
 279                 if (rnp->level != level) {
 280                         seq_puts(m, "\n");
 281                         level = rnp->level;
 282                 }
 283                 seq_printf(m, "%lx/%lx->%lx %c%c>%c %d:%d ^%d    ",
 284                            rnp->qsmask, rnp->qsmaskinit, rnp->qsmaskinitnext,
 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 *v)
 294 {
 295         struct rcu_state *rsp = (struct rcu_state *)m->private;
 296         print_one_rcu_state(m, rsp);
 297         return 0;
 298 }
 299
 300 static int rcuhier_open(struct inode *inode, struct file *file)
 301 {
 302         return single_open(file, show_rcuhier, inode->i_private);
 303 }
 304
 305 static const struct file_operations rcuhier_fops = {
 306         .owner = THIS_MODULE,
 307         .open = rcuhier_open,
 308         .read = seq_read,
 309         .llseek = no_llseek,
 310         .release = single_release,
 311 };
 312
 313 static void show_one_rcugp(struct seq_file *m, struct rcu_state *rsp)
 314 {
 315         unsigned long flags;
 316         unsigned long completed;
 317         unsigned long gpnum;
 318         unsigned long gpage;
 319         unsigned long gpmax;
 320         struct rcu_node *rnp = &rsp->node[0];
 321
 322         raw_spin_lock_irqsave(&rnp->lock, flags);
 323         completed = READ_ONCE(rsp->completed);
 324         gpnum = READ_ONCE(rsp->gpnum);
 325         if (completed == gpnum)
 326                 gpage = 0;
 327         else
 328                 gpage = jiffies - rsp->gp_start;
 329         gpmax = rsp->gp_max;
 330         raw_spin_unlock_irqrestore(&rnp->lock, flags);
 331         seq_printf(m, "completed=%ld  gpnum=%ld  age=%ld  max=%ld\n",
 332                    ulong2long(completed), ulong2long(gpnum), gpage, gpmax);
 333 }
 334
 335 static int show_rcugp(struct seq_file *m, void *v)
 336 {
 337         struct rcu_state *rsp = (struct rcu_state *)m->private;
 338         show_one_rcugp(m, rsp);
 339         return 0;
 340 }
 341
 342 static int rcugp_open(struct inode *inode, struct file *file)
 343 {
 344         return single_open(file, show_rcugp, inode->i_private);
 345 }
 346
 347 static const struct file_operations rcugp_fops = {
 348         .owner = THIS_MODULE,
 349         .open = rcugp_open,
 350         .read = seq_read,
 351         .llseek = no_llseek,
 352         .release = single_release,
 353 };
 354
 355 static void print_one_rcu_pending(struct seq_file *m, struct rcu_data *rdp)
 356 {
 357         if (!rdp->beenonline)
 358                 return;
 359         seq_printf(m, "%3d%cnp=%ld ",
 360                    rdp->cpu,
 361                    cpu_is_offline(rdp->cpu) ? '!' : ' ',
 362                    rdp->n_rcu_pending);
 363         seq_printf(m, "qsp=%ld rpq=%ld cbr=%ld cng=%ld ",
 364                    rdp->n_rp_core_needs_qs,
 365                    rdp->n_rp_report_qs,
 366                    rdp->n_rp_cb_ready,
 367                    rdp->n_rp_cpu_needs_gp);
 368         seq_printf(m, "gpc=%ld gps=%ld nn=%ld ndw%ld\n",
 369                    rdp->n_rp_gp_completed,
 370                    rdp->n_rp_gp_started,
 371                    rdp->n_rp_nocb_defer_wakeup,
 372                    rdp->n_rp_need_nothing);
 373 }
 374
 375 static int show_rcu_pending(struct seq_file *m, void *v)
 376 {
 377         print_one_rcu_pending(m, (struct rcu_data *)v);
 378         return 0;
 379 }
 380
 381 static const struct seq_operations rcu_pending_op = {
 382         .start = r_start,
 383         .next  = r_next,
 384         .stop  = r_stop,
 385         .show  = show_rcu_pending,
 386 };
 387
 388 static int rcu_pending_open(struct inode *inode, struct file *file)
 389 {
 390         return r_open(inode, file, &rcu_pending_op);
 391 }
 392
 393 static const struct file_operations rcu_pending_fops = {
 394         .owner = THIS_MODULE,
 395         .open = rcu_pending_open,
 396         .read = seq_read,
 397         .llseek = no_llseek,
 398         .release = seq_release,
 399 };
 400
 401 static int show_rcutorture(struct seq_file *m, void *unused)
 402 {
 403         seq_printf(m, "rcutorture test sequence: %lu %s\n",
 404                    rcutorture_testseq >> 1,
 405                    (rcutorture_testseq & 0x1) ? "(test in progress)" : "");
 406         seq_printf(m, "rcutorture update version number: %lu\n",
 407                    rcutorture_vernum);
 408         return 0;
 409 }
 410
 411 static int rcutorture_open(struct inode *inode, struct file *file)
 412 {
 413         return single_open(file, show_rcutorture, NULL);
 414 }
 415
 416 static const struct file_operations rcutorture_fops = {
 417         .owner = THIS_MODULE,
 418         .open = rcutorture_open,
 419         .read = seq_read,
 420         .llseek = seq_lseek,
 421         .release = single_release,
 422 };
 423
 424 static struct dentry *rcudir;
 425
 426 static int __init rcutree_trace_init(void)
 427 {
 428         struct rcu_state *rsp;
 429         struct dentry *retval;
 430         struct dentry *rspdir;
 431
 432         rcudir = debugfs_create_dir("rcu", NULL);
 433         if (!rcudir)
 434                 goto free_out;
 435
 436         for_each_rcu_flavor(rsp) {
 437                 rspdir = debugfs_create_dir(rsp->name, rcudir);
 438                 if (!rspdir)
 439                         goto free_out;
 440
 441                 retval = debugfs_create_file("rcudata", 0444,
 442                                 rspdir, rsp, &rcudata_fops);
 443                 if (!retval)
 444                         goto free_out;
 445
 446                 retval = debugfs_create_file("rcuexp", 0444,
 447                                 rspdir, rsp, &rcuexp_fops);
 448                 if (!retval)
 449                         goto free_out;
 450
 451                 retval = debugfs_create_file("rcu_pending", 0444,
 452                                 rspdir, rsp, &rcu_pending_fops);
 453                 if (!retval)
 454                         goto free_out;
 455
 456                 retval = debugfs_create_file("rcubarrier", 0444,
 457                                 rspdir, rsp, &rcubarrier_fops);
 458                 if (!retval)
 459                         goto free_out;
 460
 461 #ifdef CONFIG_RCU_BOOST
 462                 if (rsp == &rcu_preempt_state) {
 463                         retval = debugfs_create_file("rcuboost", 0444,
 464                                 rspdir, NULL, &rcu_node_boost_fops);
 465                         if (!retval)
 466                                 goto free_out;
 467                 }
 468 #endif
 469
 470                 retval = debugfs_create_file("rcugp", 0444,
 471                                 rspdir, rsp, &rcugp_fops);
 472                 if (!retval)
 473                         goto free_out;
 474
 475                 retval = debugfs_create_file("rcuhier", 0444,
 476                                 rspdir, rsp, &rcuhier_fops);
 477                 if (!retval)
 478                         goto free_out;
 479         }
 480
 481         retval = debugfs_create_file("rcutorture", 0444, rcudir,
 482                                                 NULL, &rcutorture_fops);
 483         if (!retval)
 484                 goto free_out;
 485         return 0;
 486 free_out:
 487         debugfs_remove_recursive(rcudir);
 488         return 1;
 489 }
 490
 491 static void __exit rcutree_trace_cleanup(void)
 492 {
 493         debugfs_remove_recursive(rcudir);
 494 }
 495
 496
 497 module_init(rcutree_trace_init);
 498 module_exit(rcutree_trace_cleanup);
 499
 500 MODULE_AUTHOR("Paul E. McKenney");
 501 MODULE_DESCRIPTION("Read-Copy Update tracing for hierarchical implementation");
 502 MODULE_LICENSE("GPL");