linux/kernel/rcutree_trace.c
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   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#define ulong2long(a) (*(long *)(&(a)))
  50
  51static 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
  62static 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
  71static void *r_next(struct seq_file *m, void *v, loff_t *pos)
  72{
  73        (*pos)++;
  74        return r_start(m, pos);
  75}
  76
  77static void r_stop(struct seq_file *m, void *v)
  78{
  79}
  80
  81static 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 nbd: %lu\n",
  85                   atomic_read(&rsp->barrier_cpu_count),
  86                   rsp->n_barrier_done);
  87        return 0;
  88}
  89
  90static int rcubarrier_open(struct inode *inode, struct file *file)
  91{
  92        return single_open(file, show_rcubarrier, inode->i_private);
  93}
  94
  95static 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
 105static 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
 114static 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 pq=%d qp=%d",
 121                   rdp->cpu,
 122                   cpu_is_offline(rdp->cpu) ? '!' : ' ',
 123                   ulong2long(rdp->completed), ulong2long(rdp->gpnum),
 124                   rdp->passed_quiesce, rdp->qs_pending);
 125        seq_printf(m, " dt=%d/%llx/%d df=%lu",
 126                   atomic_read(&rdp->dynticks->dynticks),
 127                   rdp->dynticks->dynticks_nesting,
 128                   rdp->dynticks->dynticks_nmi_nesting,
 129                   rdp->dynticks_fqs);
 130        seq_printf(m, " of=%lu", rdp->offline_fqs);
 131        rcu_nocb_q_lengths(rdp, &ql, &qll);
 132        qll += rdp->qlen_lazy;
 133        ql += rdp->qlen;
 134        seq_printf(m, " ql=%ld/%ld qs=%c%c%c%c",
 135                   qll, ql,
 136                   ".N"[rdp->nxttail[RCU_NEXT_READY_TAIL] !=
 137                        rdp->nxttail[RCU_NEXT_TAIL]],
 138                   ".R"[rdp->nxttail[RCU_WAIT_TAIL] !=
 139                        rdp->nxttail[RCU_NEXT_READY_TAIL]],
 140                   ".W"[rdp->nxttail[RCU_DONE_TAIL] !=
 141                        rdp->nxttail[RCU_WAIT_TAIL]],
 142                   ".D"[&rdp->nxtlist != rdp->nxttail[RCU_DONE_TAIL]]);
 143#ifdef CONFIG_RCU_BOOST
 144        seq_printf(m, " kt=%d/%c ktl=%x",
 145                   per_cpu(rcu_cpu_has_work, rdp->cpu),
 146                   convert_kthread_status(per_cpu(rcu_cpu_kthread_status,
 147                                          rdp->cpu)),
 148                   per_cpu(rcu_cpu_kthread_loops, rdp->cpu) & 0xffff);
 149#endif /* #ifdef CONFIG_RCU_BOOST */
 150        seq_printf(m, " b=%ld", rdp->blimit);
 151        seq_printf(m, " ci=%lu nci=%lu co=%lu ca=%lu\n",
 152                   rdp->n_cbs_invoked, rdp->n_nocbs_invoked,
 153                   rdp->n_cbs_orphaned, rdp->n_cbs_adopted);
 154}
 155
 156static int show_rcudata(struct seq_file *m, void *v)
 157{
 158        print_one_rcu_data(m, (struct rcu_data *)v);
 159        return 0;
 160}
 161
 162static const struct seq_operations rcudate_op = {
 163        .start = r_start,
 164        .next  = r_next,
 165        .stop  = r_stop,
 166        .show  = show_rcudata,
 167};
 168
 169static int rcudata_open(struct inode *inode, struct file *file)
 170{
 171        return r_open(inode, file, &rcudate_op);
 172}
 173
 174static const struct file_operations rcudata_fops = {
 175        .owner = THIS_MODULE,
 176        .open = rcudata_open,
 177        .read = seq_read,
 178        .llseek = no_llseek,
 179        .release = seq_release,
 180};
 181
 182static int show_rcuexp(struct seq_file *m, void *v)
 183{
 184        struct rcu_state *rsp = (struct rcu_state *)m->private;
 185
 186        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",
 187                   atomic_long_read(&rsp->expedited_start),
 188                   atomic_long_read(&rsp->expedited_done),
 189                   atomic_long_read(&rsp->expedited_wrap),
 190                   atomic_long_read(&rsp->expedited_tryfail),
 191                   atomic_long_read(&rsp->expedited_workdone1),
 192                   atomic_long_read(&rsp->expedited_workdone2),
 193                   atomic_long_read(&rsp->expedited_normal),
 194                   atomic_long_read(&rsp->expedited_stoppedcpus),
 195                   atomic_long_read(&rsp->expedited_done_tries),
 196                   atomic_long_read(&rsp->expedited_done_lost),
 197                   atomic_long_read(&rsp->expedited_done_exit));
 198        return 0;
 199}
 200
 201static int rcuexp_open(struct inode *inode, struct file *file)
 202{
 203        return single_open(file, show_rcuexp, inode->i_private);
 204}
 205
 206static const struct file_operations rcuexp_fops = {
 207        .owner = THIS_MODULE,
 208        .open = rcuexp_open,
 209        .read = seq_read,
 210        .llseek = no_llseek,
 211        .release = single_release,
 212};
 213
 214#ifdef CONFIG_RCU_BOOST
 215
 216static void print_one_rcu_node_boost(struct seq_file *m, struct rcu_node *rnp)
 217{
 218        seq_printf(m, "%d:%d tasks=%c%c%c%c kt=%c ntb=%lu neb=%lu nnb=%lu ",
 219                   rnp->grplo, rnp->grphi,
 220                   "T."[list_empty(&rnp->blkd_tasks)],
 221                   "N."[!rnp->gp_tasks],
 222                   "E."[!rnp->exp_tasks],
 223                   "B."[!rnp->boost_tasks],
 224                   convert_kthread_status(rnp->boost_kthread_status),
 225                   rnp->n_tasks_boosted, rnp->n_exp_boosts,
 226                   rnp->n_normal_boosts);
 227        seq_printf(m, "j=%04x bt=%04x\n",
 228                   (int)(jiffies & 0xffff),
 229                   (int)(rnp->boost_time & 0xffff));
 230        seq_printf(m, "    balk: nt=%lu egt=%lu bt=%lu nb=%lu ny=%lu nos=%lu\n",
 231                   rnp->n_balk_blkd_tasks,
 232                   rnp->n_balk_exp_gp_tasks,
 233                   rnp->n_balk_boost_tasks,
 234                   rnp->n_balk_notblocked,
 235                   rnp->n_balk_notyet,
 236                   rnp->n_balk_nos);
 237}
 238
 239static int show_rcu_node_boost(struct seq_file *m, void *unused)
 240{
 241        struct rcu_node *rnp;
 242
 243        rcu_for_each_leaf_node(&rcu_preempt_state, rnp)
 244                print_one_rcu_node_boost(m, rnp);
 245        return 0;
 246}
 247
 248static int rcu_node_boost_open(struct inode *inode, struct file *file)
 249{
 250        return single_open(file, show_rcu_node_boost, NULL);
 251}
 252
 253static const struct file_operations rcu_node_boost_fops = {
 254        .owner = THIS_MODULE,
 255        .open = rcu_node_boost_open,
 256        .read = seq_read,
 257        .llseek = no_llseek,
 258        .release = single_release,
 259};
 260
 261#endif /* #ifdef CONFIG_RCU_BOOST */
 262
 263static 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=%ld g=%ld s=%d jfq=%ld j=%x ",
 271                   ulong2long(rsp->completed), ulong2long(gpnum),
 272                   rsp->fqs_state,
 273                   (long)(rsp->jiffies_force_qs - jiffies),
 274                   (int)(jiffies & 0xffff));
 275        seq_printf(m, "nfqs=%lu/nfqsng=%lu(%lu) fqlh=%lu oqlen=%ld/%ld\n",
 276                   rsp->n_force_qs, rsp->n_force_qs_ngp,
 277                   rsp->n_force_qs - rsp->n_force_qs_ngp,
 278                   rsp->n_force_qs_lh, rsp->qlen_lazy, rsp->qlen);
 279        for (rnp = &rsp->node[0]; rnp - &rsp->node[0] < rcu_num_nodes; rnp++) {
 280                if (rnp->level != level) {
 281                        seq_puts(m, "\n");
 282                        level = rnp->level;
 283                }
 284                seq_printf(m, "%lx/%lx %c%c>%c %d:%d ^%d    ",
 285                           rnp->qsmask, rnp->qsmaskinit,
 286                           ".G"[rnp->gp_tasks != NULL],
 287                           ".E"[rnp->exp_tasks != NULL],
 288                           ".T"[!list_empty(&rnp->blkd_tasks)],
 289                           rnp->grplo, rnp->grphi, rnp->grpnum);
 290        }
 291        seq_puts(m, "\n");
 292}
 293
 294static int show_rcuhier(struct seq_file *m, void *v)
 295{
 296        struct rcu_state *rsp = (struct rcu_state *)m->private;
 297        print_one_rcu_state(m, rsp);
 298        return 0;
 299}
 300
 301static int rcuhier_open(struct inode *inode, struct file *file)
 302{
 303        return single_open(file, show_rcuhier, inode->i_private);
 304}
 305
 306static const struct file_operations rcuhier_fops = {
 307        .owner = THIS_MODULE,
 308        .open = rcuhier_open,
 309        .read = seq_read,
 310        .llseek = no_llseek,
 311        .release = single_release,
 312};
 313
 314static void show_one_rcugp(struct seq_file *m, struct rcu_state *rsp)
 315{
 316        unsigned long flags;
 317        unsigned long completed;
 318        unsigned long gpnum;
 319        unsigned long gpage;
 320        unsigned long gpmax;
 321        struct rcu_node *rnp = &rsp->node[0];
 322
 323        raw_spin_lock_irqsave(&rnp->lock, flags);
 324        completed = ACCESS_ONCE(rsp->completed);
 325        gpnum = ACCESS_ONCE(rsp->gpnum);
 326        if (completed == gpnum)
 327                gpage = 0;
 328        else
 329                gpage = jiffies - rsp->gp_start;
 330        gpmax = rsp->gp_max;
 331        raw_spin_unlock_irqrestore(&rnp->lock, flags);
 332        seq_printf(m, "completed=%ld  gpnum=%ld  age=%ld  max=%ld\n",
 333                   ulong2long(completed), ulong2long(gpnum), gpage, gpmax);
 334}
 335
 336static int show_rcugp(struct seq_file *m, void *v)
 337{
 338        struct rcu_state *rsp = (struct rcu_state *)m->private;
 339        show_one_rcugp(m, rsp);
 340        return 0;
 341}
 342
 343static int rcugp_open(struct inode *inode, struct file *file)
 344{
 345        return single_open(file, show_rcugp, inode->i_private);
 346}
 347
 348static const struct file_operations rcugp_fops = {
 349        .owner = THIS_MODULE,
 350        .open = rcugp_open,
 351        .read = seq_read,
 352        .llseek = no_llseek,
 353        .release = single_release,
 354};
 355
 356static void print_one_rcu_pending(struct seq_file *m, struct rcu_data *rdp)
 357{
 358        if (!rdp->beenonline)
 359                return;
 360        seq_printf(m, "%3d%cnp=%ld ",
 361                   rdp->cpu,
 362                   cpu_is_offline(rdp->cpu) ? '!' : ' ',
 363                   rdp->n_rcu_pending);
 364        seq_printf(m, "qsp=%ld rpq=%ld cbr=%ld cng=%ld ",
 365                   rdp->n_rp_qs_pending,
 366                   rdp->n_rp_report_qs,
 367                   rdp->n_rp_cb_ready,
 368                   rdp->n_rp_cpu_needs_gp);
 369        seq_printf(m, "gpc=%ld gps=%ld nn=%ld\n",
 370                   rdp->n_rp_gp_completed,
 371                   rdp->n_rp_gp_started,
 372                   rdp->n_rp_need_nothing);
 373}
 374
 375static 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
 381static 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
 388static int rcu_pending_open(struct inode *inode, struct file *file)
 389{
 390        return r_open(inode, file, &rcu_pending_op);
 391}
 392
 393static 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
 401static 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
 411static int rcutorture_open(struct inode *inode, struct file *file)
 412{
 413        return single_open(file, show_rcutorture, NULL);
 414}
 415
 416static 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
 424static struct dentry *rcudir;
 425
 426static 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;
 486free_out:
 487        debugfs_remove_recursive(rcudir);
 488        return 1;
 489}
 490
 491static void __exit rcutree_trace_cleanup(void)
 492{
 493        debugfs_remove_recursive(rcudir);
 494}
 495
 496
 497module_init(rcutree_trace_init);
 498module_exit(rcutree_trace_cleanup);
 499
 500MODULE_AUTHOR("Paul E. McKenney");
 501MODULE_DESCRIPTION("Read-Copy Update tracing for hierarchical implementation");
 502MODULE_LICENSE("GPL");
 503
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