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 nbd: %lu\n",
  85                    atomic_read(&rsp->barrier_cpu_count),
  86                    rsp->n_barrier_done);
  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 pq=%d/%d qp=%d",
 121                    rdp->cpu,
 122                    cpu_is_offline(rdp->cpu) ? '!' : ' ',
 123                    ulong2long(rdp->completed), ulong2long(rdp->gpnum),
 124                    rdp->passed_quiesce,
 125                    rdp->rcu_qs_ctr_snap == per_cpu(rcu_qs_ctr, rdp->cpu),
 126                    rdp->qs_pending);
 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 d=%lu w=%lu tf=%lu wd1=%lu wd2=%lu n=%lu sc=%lu dt=%lu dl=%lu dx=%lu\n",
 189                    atomic_long_read(&rsp->expedited_start),
 190                    atomic_long_read(&rsp->expedited_done),
 191                    atomic_long_read(&rsp->expedited_wrap),
 192                    atomic_long_read(&rsp->expedited_tryfail),
 193                    atomic_long_read(&rsp->expedited_workdone1),
 194                    atomic_long_read(&rsp->expedited_workdone2),
 195                    atomic_long_read(&rsp->expedited_normal),
 196                    atomic_long_read(&rsp->expedited_stoppedcpus),
 197                    atomic_long_read(&rsp->expedited_done_tries),
 198                    atomic_long_read(&rsp->expedited_done_lost),
 199                    atomic_long_read(&rsp->expedited_done_exit));
 200         return 0;
 201 }
 202
 203 static int rcuexp_open(struct inode *inode, struct file *file)
 204 {
 205         return single_open(file, show_rcuexp, inode->i_private);
 206 }
 207
 208 static const struct file_operations rcuexp_fops = {
 209         .owner = THIS_MODULE,
 210         .open = rcuexp_open,
 211         .read = seq_read,
 212         .llseek = no_llseek,
 213         .release = single_release,
 214 };
 215
 216 #ifdef CONFIG_RCU_BOOST
 217
 218 static void print_one_rcu_node_boost(struct seq_file *m, struct rcu_node *rnp)
 219 {
 220         seq_printf(m, "%d:%d tasks=%c%c%c%c kt=%c ntb=%lu neb=%lu nnb=%lu ",
 221                    rnp->grplo, rnp->grphi,
 222                    "T."[list_empty(&rnp->blkd_tasks)],
 223                    "N."[!rnp->gp_tasks],
 224                    "E."[!rnp->exp_tasks],
 225                    "B."[!rnp->boost_tasks],
 226                    convert_kthread_status(rnp->boost_kthread_status),
 227                    rnp->n_tasks_boosted, rnp->n_exp_boosts,
 228                    rnp->n_normal_boosts);
 229         seq_printf(m, "j=%04x bt=%04x\n",
 230                    (int)(jiffies & 0xffff),
 231                    (int)(rnp->boost_time & 0xffff));
 232         seq_printf(m, "    balk: nt=%lu egt=%lu bt=%lu nb=%lu ny=%lu nos=%lu\n",
 233                    rnp->n_balk_blkd_tasks,
 234                    rnp->n_balk_exp_gp_tasks,
 235                    rnp->n_balk_boost_tasks,
 236                    rnp->n_balk_notblocked,
 237                    rnp->n_balk_notyet,
 238                    rnp->n_balk_nos);
 239 }
 240
 241 static int show_rcu_node_boost(struct seq_file *m, void *unused)
 242 {
 243         struct rcu_node *rnp;
 244
 245         rcu_for_each_leaf_node(&rcu_preempt_state, rnp)
 246                 print_one_rcu_node_boost(m, rnp);
 247         return 0;
 248 }
 249
 250 static int rcu_node_boost_open(struct inode *inode, struct file *file)
 251 {
 252         return single_open(file, show_rcu_node_boost, NULL);
 253 }
 254
 255 static const struct file_operations rcu_node_boost_fops = {
 256         .owner = THIS_MODULE,
 257         .open = rcu_node_boost_open,
 258         .read = seq_read,
 259         .llseek = no_llseek,
 260         .release = single_release,
 261 };
 262
 263 #endif /* #ifdef CONFIG_RCU_BOOST */
 264
 265 static void print_one_rcu_state(struct seq_file *m, struct rcu_state *rsp)
 266 {
 267         unsigned long gpnum;
 268         int level = 0;
 269         struct rcu_node *rnp;
 270
 271         gpnum = rsp->gpnum;
 272         seq_printf(m, "c=%ld g=%ld s=%d jfq=%ld j=%x ",
 273                    ulong2long(rsp->completed), ulong2long(gpnum),
 274                    rsp->fqs_state,
 275                    (long)(rsp->jiffies_force_qs - jiffies),
 276                    (int)(jiffies & 0xffff));
 277         seq_printf(m, "nfqs=%lu/nfqsng=%lu(%lu) fqlh=%lu oqlen=%ld/%ld\n",
 278                    rsp->n_force_qs, rsp->n_force_qs_ngp,
 279                    rsp->n_force_qs - rsp->n_force_qs_ngp,
 280                    READ_ONCE(rsp->n_force_qs_lh), rsp->qlen_lazy, rsp->qlen);
 281         for (rnp = &rsp->node[0]; rnp - &rsp->node[0] < rcu_num_nodes; rnp++) {
 282                 if (rnp->level != level) {
 283                         seq_puts(m, "\n");
 284                         level = rnp->level;
 285                 }
 286                 seq_printf(m, "%lx/%lx->%lx %c%c>%c %d:%d ^%d    ",
 287                            rnp->qsmask, rnp->qsmaskinit, rnp->qsmaskinitnext,
 288                            ".G"[rnp->gp_tasks != NULL],
 289                            ".E"[rnp->exp_tasks != NULL],
 290                            ".T"[!list_empty(&rnp->blkd_tasks)],
 291                            rnp->grplo, rnp->grphi, rnp->grpnum);
 292         }
 293         seq_puts(m, "\n");
 294 }
 295
 296 static int show_rcuhier(struct seq_file *m, void *v)
 297 {
 298         struct rcu_state *rsp = (struct rcu_state *)m->private;
 299         print_one_rcu_state(m, rsp);
 300         return 0;
 301 }
 302
 303 static int rcuhier_open(struct inode *inode, struct file *file)
 304 {
 305         return single_open(file, show_rcuhier, inode->i_private);
 306 }
 307
 308 static const struct file_operations rcuhier_fops = {
 309         .owner = THIS_MODULE,
 310         .open = rcuhier_open,
 311         .read = seq_read,
 312         .llseek = no_llseek,
 313         .release = single_release,
 314 };
 315
 316 static void show_one_rcugp(struct seq_file *m, struct rcu_state *rsp)
 317 {
 318         unsigned long flags;
 319         unsigned long completed;
 320         unsigned long gpnum;
 321         unsigned long gpage;
 322         unsigned long gpmax;
 323         struct rcu_node *rnp = &rsp->node[0];
 324
 325         raw_spin_lock_irqsave(&rnp->lock, flags);
 326         completed = READ_ONCE(rsp->completed);
 327         gpnum = READ_ONCE(rsp->gpnum);
 328         if (completed == gpnum)
 329                 gpage = 0;
 330         else
 331                 gpage = jiffies - rsp->gp_start;
 332         gpmax = rsp->gp_max;
 333         raw_spin_unlock_irqrestore(&rnp->lock, flags);
 334         seq_printf(m, "completed=%ld  gpnum=%ld  age=%ld  max=%ld\n",
 335                    ulong2long(completed), ulong2long(gpnum), gpage, gpmax);
 336 }
 337
 338 static int show_rcugp(struct seq_file *m, void *v)
 339 {
 340         struct rcu_state *rsp = (struct rcu_state *)m->private;
 341         show_one_rcugp(m, rsp);
 342         return 0;
 343 }
 344
 345 static int rcugp_open(struct inode *inode, struct file *file)
 346 {
 347         return single_open(file, show_rcugp, inode->i_private);
 348 }
 349
 350 static const struct file_operations rcugp_fops = {
 351         .owner = THIS_MODULE,
 352         .open = rcugp_open,
 353         .read = seq_read,
 354         .llseek = no_llseek,
 355         .release = single_release,
 356 };
 357
 358 static void print_one_rcu_pending(struct seq_file *m, struct rcu_data *rdp)
 359 {
 360         if (!rdp->beenonline)
 361                 return;
 362         seq_printf(m, "%3d%cnp=%ld ",
 363                    rdp->cpu,
 364                    cpu_is_offline(rdp->cpu) ? '!' : ' ',
 365                    rdp->n_rcu_pending);
 366         seq_printf(m, "qsp=%ld rpq=%ld cbr=%ld cng=%ld ",
 367                    rdp->n_rp_qs_pending,
 368                    rdp->n_rp_report_qs,
 369                    rdp->n_rp_cb_ready,
 370                    rdp->n_rp_cpu_needs_gp);
 371         seq_printf(m, "gpc=%ld gps=%ld nn=%ld ndw%ld\n",
 372                    rdp->n_rp_gp_completed,
 373                    rdp->n_rp_gp_started,
 374                    rdp->n_rp_nocb_defer_wakeup,
 375                    rdp->n_rp_need_nothing);
 376 }
 377
 378 static int show_rcu_pending(struct seq_file *m, void *v)
 379 {
 380         print_one_rcu_pending(m, (struct rcu_data *)v);
 381         return 0;
 382 }
 383
 384 static const struct seq_operations rcu_pending_op = {
 385         .start = r_start,
 386         .next  = r_next,
 387         .stop  = r_stop,
 388         .show  = show_rcu_pending,
 389 };
 390
 391 static int rcu_pending_open(struct inode *inode, struct file *file)
 392 {
 393         return r_open(inode, file, &rcu_pending_op);
 394 }
 395
 396 static const struct file_operations rcu_pending_fops = {
 397         .owner = THIS_MODULE,
 398         .open = rcu_pending_open,
 399         .read = seq_read,
 400         .llseek = no_llseek,
 401         .release = seq_release,
 402 };
 403
 404 static int show_rcutorture(struct seq_file *m, void *unused)
 405 {
 406         seq_printf(m, "rcutorture test sequence: %lu %s\n",
 407                    rcutorture_testseq >> 1,
 408                    (rcutorture_testseq & 0x1) ? "(test in progress)" : "");
 409         seq_printf(m, "rcutorture update version number: %lu\n",
 410                    rcutorture_vernum);
 411         return 0;
 412 }
 413
 414 static int rcutorture_open(struct inode *inode, struct file *file)
 415 {
 416         return single_open(file, show_rcutorture, NULL);
 417 }
 418
 419 static const struct file_operations rcutorture_fops = {
 420         .owner = THIS_MODULE,
 421         .open = rcutorture_open,
 422         .read = seq_read,
 423         .llseek = seq_lseek,
 424         .release = single_release,
 425 };
 426
 427 static struct dentry *rcudir;
 428
 429 static int __init rcutree_trace_init(void)
 430 {
 431         struct rcu_state *rsp;
 432         struct dentry *retval;
 433         struct dentry *rspdir;
 434
 435         rcudir = debugfs_create_dir("rcu", NULL);
 436         if (!rcudir)
 437                 goto free_out;
 438
 439         for_each_rcu_flavor(rsp) {
 440                 rspdir = debugfs_create_dir(rsp->name, rcudir);
 441                 if (!rspdir)
 442                         goto free_out;
 443
 444                 retval = debugfs_create_file("rcudata", 0444,
 445                                 rspdir, rsp, &rcudata_fops);
 446                 if (!retval)
 447                         goto free_out;
 448
 449                 retval = debugfs_create_file("rcuexp", 0444,
 450                                 rspdir, rsp, &rcuexp_fops);
 451                 if (!retval)
 452                         goto free_out;
 453
 454                 retval = debugfs_create_file("rcu_pending", 0444,
 455                                 rspdir, rsp, &rcu_pending_fops);
 456                 if (!retval)
 457                         goto free_out;
 458
 459                 retval = debugfs_create_file("rcubarrier", 0444,
 460                                 rspdir, rsp, &rcubarrier_fops);
 461                 if (!retval)
 462                         goto free_out;
 463
 464 #ifdef CONFIG_RCU_BOOST
 465                 if (rsp == &rcu_preempt_state) {
 466                         retval = debugfs_create_file("rcuboost", 0444,
 467                                 rspdir, NULL, &rcu_node_boost_fops);
 468                         if (!retval)
 469                                 goto free_out;
 470                 }
 471 #endif
 472
 473                 retval = debugfs_create_file("rcugp", 0444,
 474                                 rspdir, rsp, &rcugp_fops);
 475                 if (!retval)
 476                         goto free_out;
 477
 478                 retval = debugfs_create_file("rcuhier", 0444,
 479                                 rspdir, rsp, &rcuhier_fops);
 480                 if (!retval)
 481                         goto free_out;
 482         }
 483
 484         retval = debugfs_create_file("rcutorture", 0444, rcudir,
 485                                                 NULL, &rcutorture_fops);
 486         if (!retval)
 487                 goto free_out;
 488         return 0;
 489 free_out:
 490         debugfs_remove_recursive(rcudir);
 491         return 1;
 492 }
 493
 494 static void __exit rcutree_trace_cleanup(void)
 495 {
 496         debugfs_remove_recursive(rcudir);
 497 }
 498
 499
 500 module_init(rcutree_trace_init);
 501 module_exit(rcutree_trace_cleanup);
 502
 503 MODULE_AUTHOR("Paul E. McKenney");
 504 MODULE_DESCRIPTION("Read-Copy Update tracing for hierarchical implementation");
 505 MODULE_LICENSE("GPL");