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 static int r_open(struct inode *inode, struct file *file,
  50                                         const struct seq_operations *op)
  51 {
  52         int ret = seq_open(file, op);
  53         if (!ret) {
  54                 struct seq_file *m = (struct seq_file *)file->private_data;
  55                 m->private = inode->i_private;
  56         }
  57         return ret;
  58 }
  59
  60 static void *r_start(struct seq_file *m, loff_t *pos)
  61 {
  62         struct rcu_state *rsp = (struct rcu_state *)m->private;
  63         *pos = cpumask_next(*pos - 1, cpu_possible_mask);
  64         if ((*pos) < nr_cpu_ids)
  65                 return per_cpu_ptr(rsp->rda, *pos);
  66         return NULL;
  67 }
  68
  69 static void *r_next(struct seq_file *m, void *v, loff_t *pos)
  70 {
  71         (*pos)++;
  72         return r_start(m, pos);
  73 }
  74
  75 static void r_stop(struct seq_file *m, void *v)
  76 {
  77 }
  78
  79 static int show_rcubarrier(struct seq_file *m, void *v)
  80 {
  81         struct rcu_state *rsp = (struct rcu_state *)m->private;
  82         seq_printf(m, "bcc: %d nbd: %lu\n",
  83                    atomic_read(&rsp->barrier_cpu_count),
  84                    rsp->n_barrier_done);
  85         return 0;
  86 }
  87
  88 static int rcubarrier_open(struct inode *inode, struct file *file)
  89 {
  90         return single_open(file, show_rcubarrier, inode->i_private);
  91 }
  92
  93 static const struct file_operations rcubarrier_fops = {
  94         .owner = THIS_MODULE,
  95         .open = rcubarrier_open,
  96         .read = seq_read,
  97         .llseek = no_llseek,
  98         .release = single_release,
  99 };
 100
 101 #ifdef CONFIG_RCU_BOOST
 102
 103 static char convert_kthread_status(unsigned int kthread_status)
 104 {
 105         if (kthread_status > RCU_KTHREAD_MAX)
 106                 return '?';
 107         return "SRWOY"[kthread_status];
 108 }
 109
 110 #endif /* #ifdef CONFIG_RCU_BOOST */
 111
 112 static void print_one_rcu_data(struct seq_file *m, struct rcu_data *rdp)
 113 {
 114         long ql, qll;
 115
 116         if (!rdp->beenonline)
 117                 return;
 118         seq_printf(m, "%3d%cc=%ld g=%ld pq=%d qp=%d",
 119                    rdp->cpu,
 120                    cpu_is_offline(rdp->cpu) ? '!' : ' ',
 121                    ulong2long(rdp->completed), ulong2long(rdp->gpnum),
 122                    rdp->passed_quiesce, rdp->qs_pending);
 123         seq_printf(m, " dt=%d/%llx/%d df=%lu",
 124                    atomic_read(&rdp->dynticks->dynticks),
 125                    rdp->dynticks->dynticks_nesting,
 126                    rdp->dynticks->dynticks_nmi_nesting,
 127                    rdp->dynticks_fqs);
 128         seq_printf(m, " of=%lu", rdp->offline_fqs);
 129         rcu_nocb_q_lengths(rdp, &ql, &qll);
 130         qll += rdp->qlen_lazy;
 131         ql += rdp->qlen;
 132         seq_printf(m, " ql=%ld/%ld qs=%c%c%c%c",
 133                    qll, ql,
 134                    ".N"[rdp->nxttail[RCU_NEXT_READY_TAIL] !=
 135                         rdp->nxttail[RCU_NEXT_TAIL]],
 136                    ".R"[rdp->nxttail[RCU_WAIT_TAIL] !=
 137                         rdp->nxttail[RCU_NEXT_READY_TAIL]],
 138                    ".W"[rdp->nxttail[RCU_DONE_TAIL] !=
 139                         rdp->nxttail[RCU_WAIT_TAIL]],
 140                    ".D"[&rdp->nxtlist != rdp->nxttail[RCU_DONE_TAIL]]);
 141 #ifdef CONFIG_RCU_BOOST
 142         seq_printf(m, " kt=%d/%c ktl=%x",
 143                    per_cpu(rcu_cpu_has_work, rdp->cpu),
 144                    convert_kthread_status(per_cpu(rcu_cpu_kthread_status,
 145                                           rdp->cpu)),
 146                    per_cpu(rcu_cpu_kthread_loops, rdp->cpu) & 0xffff);
 147 #endif /* #ifdef CONFIG_RCU_BOOST */
 148         seq_printf(m, " b=%ld", rdp->blimit);
 149         seq_printf(m, " ci=%lu nci=%lu co=%lu ca=%lu\n",
 150                    rdp->n_cbs_invoked, rdp->n_nocbs_invoked,
 151                    rdp->n_cbs_orphaned, rdp->n_cbs_adopted);
 152 }
 153
 154 static int show_rcudata(struct seq_file *m, void *v)
 155 {
 156         print_one_rcu_data(m, (struct rcu_data *)v);
 157         return 0;
 158 }
 159
 160 static const struct seq_operations rcudate_op = {
 161         .start = r_start,
 162         .next  = r_next,
 163         .stop  = r_stop,
 164         .show  = show_rcudata,
 165 };
 166
 167 static int rcudata_open(struct inode *inode, struct file *file)
 168 {
 169         return r_open(inode, file, &rcudate_op);
 170 }
 171
 172 static const struct file_operations rcudata_fops = {
 173         .owner = THIS_MODULE,
 174         .open = rcudata_open,
 175         .read = seq_read,
 176         .llseek = no_llseek,
 177         .release = seq_release,
 178 };
 179
 180 static int show_rcuexp(struct seq_file *m, void *v)
 181 {
 182         struct rcu_state *rsp = (struct rcu_state *)m->private;
 183
 184         seq_printf(m, "s=%lu d=%lu w=%lu tf=%lu wd1=%lu wd2=%lu n=%lu sc=%lu dt=%lu dl=%lu dx=%lu\n",
 185                    atomic_long_read(&rsp->expedited_start),
 186                    atomic_long_read(&rsp->expedited_done),
 187                    atomic_long_read(&rsp->expedited_wrap),
 188                    atomic_long_read(&rsp->expedited_tryfail),
 189                    atomic_long_read(&rsp->expedited_workdone1),
 190                    atomic_long_read(&rsp->expedited_workdone2),
 191                    atomic_long_read(&rsp->expedited_normal),
 192                    atomic_long_read(&rsp->expedited_stoppedcpus),
 193                    atomic_long_read(&rsp->expedited_done_tries),
 194                    atomic_long_read(&rsp->expedited_done_lost),
 195                    atomic_long_read(&rsp->expedited_done_exit));
 196         return 0;
 197 }
 198
 199 static int rcuexp_open(struct inode *inode, struct file *file)
 200 {
 201         return single_open(file, show_rcuexp, inode->i_private);
 202 }
 203
 204 static const struct file_operations rcuexp_fops = {
 205         .owner = THIS_MODULE,
 206         .open = rcuexp_open,
 207         .read = seq_read,
 208         .llseek = no_llseek,
 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                    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         seq_printf(m, "j=%04x bt=%04x\n",
 226                    (int)(jiffies & 0xffff),
 227                    (int)(rnp->boost_time & 0xffff));
 228         seq_printf(m, "    balk: nt=%lu egt=%lu bt=%lu nb=%lu ny=%lu nos=%lu\n",
 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 = no_llseek,
 256         .release = single_release,
 257 };
 258
 259 #endif /* #ifdef CONFIG_RCU_BOOST */
 260
 261 static void print_one_rcu_state(struct seq_file *m, struct rcu_state *rsp)
 262 {
 263         unsigned long gpnum;
 264         int level = 0;
 265         struct rcu_node *rnp;
 266
 267         gpnum = rsp->gpnum;
 268         seq_printf(m, "c=%ld g=%ld s=%d jfq=%ld j=%x ",
 269                    ulong2long(rsp->completed), ulong2long(gpnum),
 270                    rsp->fqs_state,
 271                    (long)(rsp->jiffies_force_qs - jiffies),
 272                    (int)(jiffies & 0xffff));
 273         seq_printf(m, "nfqs=%lu/nfqsng=%lu(%lu) fqlh=%lu oqlen=%ld/%ld\n",
 274                    rsp->n_force_qs, rsp->n_force_qs_ngp,
 275                    rsp->n_force_qs - rsp->n_force_qs_ngp,
 276                    ACCESS_ONCE(rsp->n_force_qs_lh), rsp->qlen_lazy, rsp->qlen);
 277         for (rnp = &rsp->node[0]; rnp - &rsp->node[0] < rcu_num_nodes; rnp++) {
 278                 if (rnp->level != level) {
 279                         seq_puts(m, "\n");
 280                         level = rnp->level;
 281                 }
 282                 seq_printf(m, "%lx/%lx %c%c>%c %d:%d ^%d    ",
 283                            rnp->qsmask, rnp->qsmaskinit,
 284                            ".G"[rnp->gp_tasks != NULL],
 285                            ".E"[rnp->exp_tasks != NULL],
 286                            ".T"[!list_empty(&rnp->blkd_tasks)],
 287                            rnp->grplo, rnp->grphi, rnp->grpnum);
 288         }
 289         seq_puts(m, "\n");
 290 }
 291
 292 static int show_rcuhier(struct seq_file *m, void *v)
 293 {
 294         struct rcu_state *rsp = (struct rcu_state *)m->private;
 295         print_one_rcu_state(m, rsp);
 296         return 0;
 297 }
 298
 299 static int rcuhier_open(struct inode *inode, struct file *file)
 300 {
 301         return single_open(file, show_rcuhier, inode->i_private);
 302 }
 303
 304 static const struct file_operations rcuhier_fops = {
 305         .owner = THIS_MODULE,
 306         .open = rcuhier_open,
 307         .read = seq_read,
 308         .llseek = no_llseek,
 309         .release = single_release,
 310 };
 311
 312 static void show_one_rcugp(struct seq_file *m, struct rcu_state *rsp)
 313 {
 314         unsigned long flags;
 315         unsigned long completed;
 316         unsigned long gpnum;
 317         unsigned long gpage;
 318         unsigned long gpmax;
 319         struct rcu_node *rnp = &rsp->node[0];
 320
 321         raw_spin_lock_irqsave(&rnp->lock, flags);
 322         completed = ACCESS_ONCE(rsp->completed);
 323         gpnum = ACCESS_ONCE(rsp->gpnum);
 324         if (completed == gpnum)
 325                 gpage = 0;
 326         else
 327                 gpage = jiffies - rsp->gp_start;
 328         gpmax = rsp->gp_max;
 329         raw_spin_unlock_irqrestore(&rnp->lock, flags);
 330         seq_printf(m, "completed=%ld  gpnum=%ld  age=%ld  max=%ld\n",
 331                    ulong2long(completed), ulong2long(gpnum), gpage, gpmax);
 332 }
 333
 334 static int show_rcugp(struct seq_file *m, void *v)
 335 {
 336         struct rcu_state *rsp = (struct rcu_state *)m->private;
 337         show_one_rcugp(m, rsp);
 338         return 0;
 339 }
 340
 341 static int rcugp_open(struct inode *inode, struct file *file)
 342 {
 343         return single_open(file, show_rcugp, inode->i_private);
 344 }
 345
 346 static const struct file_operations rcugp_fops = {
 347         .owner = THIS_MODULE,
 348         .open = rcugp_open,
 349         .read = seq_read,
 350         .llseek = no_llseek,
 351         .release = single_release,
 352 };
 353
 354 static void print_one_rcu_pending(struct seq_file *m, struct rcu_data *rdp)
 355 {
 356         if (!rdp->beenonline)
 357                 return;
 358         seq_printf(m, "%3d%cnp=%ld ",
 359                    rdp->cpu,
 360                    cpu_is_offline(rdp->cpu) ? '!' : ' ',
 361                    rdp->n_rcu_pending);
 362         seq_printf(m, "qsp=%ld rpq=%ld cbr=%ld cng=%ld ",
 363                    rdp->n_rp_qs_pending,
 364                    rdp->n_rp_report_qs,
 365                    rdp->n_rp_cb_ready,
 366                    rdp->n_rp_cpu_needs_gp);
 367         seq_printf(m, "gpc=%ld gps=%ld nn=%ld ndw%ld\n",
 368                    rdp->n_rp_gp_completed,
 369                    rdp->n_rp_gp_started,
 370                    rdp->n_rp_nocb_defer_wakeup,
 371                    rdp->n_rp_need_nothing);
 372 }
 373
 374 static int show_rcu_pending(struct seq_file *m, void *v)
 375 {
 376         print_one_rcu_pending(m, (struct rcu_data *)v);
 377         return 0;
 378 }
 379
 380 static const struct seq_operations rcu_pending_op = {
 381         .start = r_start,
 382         .next  = r_next,
 383         .stop  = r_stop,
 384         .show  = show_rcu_pending,
 385 };
 386
 387 static int rcu_pending_open(struct inode *inode, struct file *file)
 388 {
 389         return r_open(inode, file, &rcu_pending_op);
 390 }
 391
 392 static const struct file_operations rcu_pending_fops = {
 393         .owner = THIS_MODULE,
 394         .open = rcu_pending_open,
 395         .read = seq_read,
 396         .llseek = no_llseek,
 397         .release = seq_release,
 398 };
 399
 400 static int show_rcutorture(struct seq_file *m, void *unused)
 401 {
 402         seq_printf(m, "rcutorture test sequence: %lu %s\n",
 403                    rcutorture_testseq >> 1,
 404                    (rcutorture_testseq & 0x1) ? "(test in progress)" : "");
 405         seq_printf(m, "rcutorture update version number: %lu\n",
 406                    rcutorture_vernum);
 407         return 0;
 408 }
 409
 410 static int rcutorture_open(struct inode *inode, struct file *file)
 411 {
 412         return single_open(file, show_rcutorture, NULL);
 413 }
 414
 415 static const struct file_operations rcutorture_fops = {
 416         .owner = THIS_MODULE,
 417         .open = rcutorture_open,
 418         .read = seq_read,
 419         .llseek = seq_lseek,
 420         .release = single_release,
 421 };
 422
 423 static struct dentry *rcudir;
 424
 425 static int __init rcutree_trace_init(void)
 426 {
 427         struct rcu_state *rsp;
 428         struct dentry *retval;
 429         struct dentry *rspdir;
 430
 431         rcudir = debugfs_create_dir("rcu", NULL);
 432         if (!rcudir)
 433                 goto free_out;
 434
 435         for_each_rcu_flavor(rsp) {
 436                 rspdir = debugfs_create_dir(rsp->name, rcudir);
 437                 if (!rspdir)
 438                         goto free_out;
 439
 440                 retval = debugfs_create_file("rcudata", 0444,
 441                                 rspdir, rsp, &rcudata_fops);
 442                 if (!retval)
 443                         goto free_out;
 444
 445                 retval = debugfs_create_file("rcuexp", 0444,
 446                                 rspdir, rsp, &rcuexp_fops);
 447                 if (!retval)
 448                         goto free_out;
 449
 450                 retval = debugfs_create_file("rcu_pending", 0444,
 451                                 rspdir, rsp, &rcu_pending_fops);
 452                 if (!retval)
 453                         goto free_out;
 454
 455                 retval = debugfs_create_file("rcubarrier", 0444,
 456                                 rspdir, rsp, &rcubarrier_fops);
 457                 if (!retval)
 458                         goto free_out;
 459
 460 #ifdef CONFIG_RCU_BOOST
 461                 if (rsp == &rcu_preempt_state) {
 462                         retval = debugfs_create_file("rcuboost", 0444,
 463                                 rspdir, NULL, &rcu_node_boost_fops);
 464                         if (!retval)
 465                                 goto free_out;
 466                 }
 467 #endif
 468
 469                 retval = debugfs_create_file("rcugp", 0444,
 470                                 rspdir, rsp, &rcugp_fops);
 471                 if (!retval)
 472                         goto free_out;
 473
 474                 retval = debugfs_create_file("rcuhier", 0444,
 475                                 rspdir, rsp, &rcuhier_fops);
 476                 if (!retval)
 477                         goto free_out;
 478         }
 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");