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 #define ulong2long(a) (*(long *)(&(a)))
  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 *unused)
  82 {
  83         struct rcu_state *rsp;
  84
  85         for_each_rcu_flavor(rsp)
  86                 seq_printf(m, "%s: bcc: %d nbd: %lu\n",
  87                            rsp->name,
  88                            atomic_read(&rsp->barrier_cpu_count),
  89                            rsp->n_barrier_done);
  90         return 0;
  91 }
  92
  93 static int rcubarrier_open(struct inode *inode, struct file *file)
  94 {
  95         return single_open(file, show_rcubarrier, NULL);
  96 }
  97
  98 static const struct file_operations rcubarrier_fops = {
  99         .owner = THIS_MODULE,
 100         .open = rcubarrier_open,
 101         .read = seq_read,
 102         .llseek = seq_lseek,
 103         .release = single_release,
 104 };
 105
 106 static int new_show_rcubarrier(struct seq_file *m, void *v)
 107 {
 108         struct rcu_state *rsp = (struct rcu_state *)m->private;
 109         seq_printf(m, "bcc: %d nbd: %lu\n",
 110                    atomic_read(&rsp->barrier_cpu_count),
 111                    rsp->n_barrier_done);
 112         return 0;
 113 }
 114
 115 static int new_rcubarrier_open(struct inode *inode, struct file *file)
 116 {
 117         return single_open(file, new_show_rcubarrier, inode->i_private);
 118 }
 119
 120 static const struct file_operations new_rcubarrier_fops = {
 121         .owner = THIS_MODULE,
 122         .open = new_rcubarrier_open,
 123         .read = seq_read,
 124         .llseek = no_llseek,
 125         .release = seq_release,
 126 };
 127
 128 #ifdef CONFIG_RCU_BOOST
 129
 130 static char convert_kthread_status(unsigned int kthread_status)
 131 {
 132         if (kthread_status > RCU_KTHREAD_MAX)
 133                 return '?';
 134         return "SRWOY"[kthread_status];
 135 }
 136
 137 #endif /* #ifdef CONFIG_RCU_BOOST */
 138
 139 static void print_one_rcu_data(struct seq_file *m, struct rcu_data *rdp)
 140 {
 141         if (!rdp->beenonline)
 142                 return;
 143         seq_printf(m, "%3d%cc=%ld g=%ld pq=%d qp=%d",
 144                    rdp->cpu,
 145                    cpu_is_offline(rdp->cpu) ? '!' : ' ',
 146                    ulong2long(rdp->completed), ulong2long(rdp->gpnum),
 147                    rdp->passed_quiesce, rdp->qs_pending);
 148         seq_printf(m, " dt=%d/%llx/%d df=%lu",
 149                    atomic_read(&rdp->dynticks->dynticks),
 150                    rdp->dynticks->dynticks_nesting,
 151                    rdp->dynticks->dynticks_nmi_nesting,
 152                    rdp->dynticks_fqs);
 153         seq_printf(m, " of=%lu", rdp->offline_fqs);
 154         seq_printf(m, " ql=%ld/%ld qs=%c%c%c%c",
 155                    rdp->qlen_lazy, rdp->qlen,
 156                    ".N"[rdp->nxttail[RCU_NEXT_READY_TAIL] !=
 157                         rdp->nxttail[RCU_NEXT_TAIL]],
 158                    ".R"[rdp->nxttail[RCU_WAIT_TAIL] !=
 159                         rdp->nxttail[RCU_NEXT_READY_TAIL]],
 160                    ".W"[rdp->nxttail[RCU_DONE_TAIL] !=
 161                         rdp->nxttail[RCU_WAIT_TAIL]],
 162                    ".D"[&rdp->nxtlist != rdp->nxttail[RCU_DONE_TAIL]]);
 163 #ifdef CONFIG_RCU_BOOST
 164         seq_printf(m, " kt=%d/%c ktl=%x",
 165                    per_cpu(rcu_cpu_has_work, rdp->cpu),
 166                    convert_kthread_status(per_cpu(rcu_cpu_kthread_status,
 167                                           rdp->cpu)),
 168                    per_cpu(rcu_cpu_kthread_loops, rdp->cpu) & 0xffff);
 169 #endif /* #ifdef CONFIG_RCU_BOOST */
 170         seq_printf(m, " b=%ld", rdp->blimit);
 171         seq_printf(m, " ci=%lu co=%lu ca=%lu\n",
 172                    rdp->n_cbs_invoked, rdp->n_cbs_orphaned, rdp->n_cbs_adopted);
 173 }
 174
 175 static int show_rcudata(struct seq_file *m, void *v)
 176 {
 177         print_one_rcu_data(m, (struct rcu_data *)v);
 178         return 0;
 179 }
 180
 181 static const struct seq_operations rcudate_op = {
 182         .start = r_start,
 183         .next  = r_next,
 184         .stop  = r_stop,
 185         .show  = show_rcudata,
 186 };
 187
 188 static int rcudata_open(struct inode *inode, struct file *file)
 189 {
 190         return r_open(inode, file, &rcudate_op);
 191 }
 192
 193 static const struct file_operations rcudata_fops = {
 194         .owner = THIS_MODULE,
 195         .open = rcudata_open,
 196         .read = seq_read,
 197         .llseek = no_llseek,
 198         .release = seq_release,
 199 };
 200
 201 #ifdef CONFIG_RCU_BOOST
 202
 203 static void print_one_rcu_node_boost(struct seq_file *m, struct rcu_node *rnp)
 204 {
 205         seq_printf(m, "%d:%d tasks=%c%c%c%c kt=%c ntb=%lu neb=%lu nnb=%lu ",
 206                    rnp->grplo, rnp->grphi,
 207                    "T."[list_empty(&rnp->blkd_tasks)],
 208                    "N."[!rnp->gp_tasks],
 209                    "E."[!rnp->exp_tasks],
 210                    "B."[!rnp->boost_tasks],
 211                    convert_kthread_status(rnp->boost_kthread_status),
 212                    rnp->n_tasks_boosted, rnp->n_exp_boosts,
 213                    rnp->n_normal_boosts);
 214         seq_printf(m, "j=%04x bt=%04x\n",
 215                    (int)(jiffies & 0xffff),
 216                    (int)(rnp->boost_time & 0xffff));
 217         seq_printf(m, "    balk: nt=%lu egt=%lu bt=%lu nb=%lu ny=%lu nos=%lu\n",
 218                    rnp->n_balk_blkd_tasks,
 219                    rnp->n_balk_exp_gp_tasks,
 220                    rnp->n_balk_boost_tasks,
 221                    rnp->n_balk_notblocked,
 222                    rnp->n_balk_notyet,
 223                    rnp->n_balk_nos);
 224 }
 225
 226 static int show_rcu_node_boost(struct seq_file *m, void *unused)
 227 {
 228         struct rcu_node *rnp;
 229
 230         rcu_for_each_leaf_node(&rcu_preempt_state, rnp)
 231                 print_one_rcu_node_boost(m, rnp);
 232         return 0;
 233 }
 234
 235 static int rcu_node_boost_open(struct inode *inode, struct file *file)
 236 {
 237         return single_open(file, show_rcu_node_boost, NULL);
 238 }
 239
 240 static const struct file_operations rcu_node_boost_fops = {
 241         .owner = THIS_MODULE,
 242         .open = rcu_node_boost_open,
 243         .read = seq_read,
 244         .llseek = no_llseek,
 245         .release = single_release,
 246 };
 247
 248 /*
 249  * Create the rcuboost debugfs entry.  Standard error return.
 250  */
 251 static int rcu_boost_trace_create_file(struct dentry *rcudir)
 252 {
 253         return !debugfs_create_file("rcuboost", 0444, rcudir, NULL,
 254                                     &rcu_node_boost_fops);
 255 }
 256
 257 #else /* #ifdef CONFIG_RCU_BOOST */
 258
 259 static int rcu_boost_trace_create_file(struct dentry *rcudir)
 260 {
 261         return 0;  /* There cannot be an error if we didn't create it! */
 262 }
 263
 264 #endif /* #else #ifdef CONFIG_RCU_BOOST */
 265
 266 static void print_one_rcu_state(struct seq_file *m, struct rcu_state *rsp)
 267 {
 268         unsigned long gpnum;
 269         int level = 0;
 270         struct rcu_node *rnp;
 271
 272         gpnum = rsp->gpnum;
 273         seq_printf(m, "%s: c=%ld g=%ld s=%d jfq=%ld j=%x ",
 274                    rsp->name, ulong2long(rsp->completed), ulong2long(gpnum),
 275                    rsp->fqs_state,
 276                    (long)(rsp->jiffies_force_qs - jiffies),
 277                    (int)(jiffies & 0xffff));
 278         seq_printf(m, "nfqs=%lu/nfqsng=%lu(%lu) fqlh=%lu oqlen=%ld/%ld\n",
 279                    rsp->n_force_qs, rsp->n_force_qs_ngp,
 280                    rsp->n_force_qs - rsp->n_force_qs_ngp,
 281                    rsp->n_force_qs_lh, rsp->qlen_lazy, rsp->qlen);
 282         for (rnp = &rsp->node[0]; rnp - &rsp->node[0] < rcu_num_nodes; rnp++) {
 283                 if (rnp->level != level) {
 284                         seq_puts(m, "\n");
 285                         level = rnp->level;
 286                 }
 287                 seq_printf(m, "%lx/%lx %c%c>%c %d:%d ^%d    ",
 288                            rnp->qsmask, rnp->qsmaskinit,
 289                            ".G"[rnp->gp_tasks != NULL],
 290                            ".E"[rnp->exp_tasks != NULL],
 291                            ".T"[!list_empty(&rnp->blkd_tasks)],
 292                            rnp->grplo, rnp->grphi, rnp->grpnum);
 293         }
 294         seq_puts(m, "\n");
 295 }
 296
 297 static int show_rcuhier(struct seq_file *m, void *unused)
 298 {
 299         struct rcu_state *rsp;
 300
 301         for_each_rcu_flavor(rsp)
 302                 print_one_rcu_state(m, rsp);
 303         return 0;
 304 }
 305
 306 static int rcuhier_open(struct inode *inode, struct file *file)
 307 {
 308         return single_open(file, show_rcuhier, NULL);
 309 }
 310
 311 static const struct file_operations rcuhier_fops = {
 312         .owner = THIS_MODULE,
 313         .open = rcuhier_open,
 314         .read = seq_read,
 315         .llseek = seq_lseek,
 316         .release = single_release,
 317 };
 318
 319 static void show_one_rcugp(struct seq_file *m, struct rcu_state *rsp)
 320 {
 321         unsigned long flags;
 322         unsigned long completed;
 323         unsigned long gpnum;
 324         unsigned long gpage;
 325         unsigned long gpmax;
 326         struct rcu_node *rnp = &rsp->node[0];
 327
 328         raw_spin_lock_irqsave(&rnp->lock, flags);
 329         completed = ACCESS_ONCE(rsp->completed);
 330         gpnum = ACCESS_ONCE(rsp->gpnum);
 331         if (completed == gpnum)
 332                 gpage = 0;
 333         else
 334                 gpage = jiffies - rsp->gp_start;
 335         gpmax = rsp->gp_max;
 336         raw_spin_unlock_irqrestore(&rnp->lock, flags);
 337         seq_printf(m, "%s: completed=%ld  gpnum=%ld  age=%ld  max=%ld\n",
 338                    rsp->name, ulong2long(completed), ulong2long(gpnum), gpage, gpmax);
 339 }
 340
 341 static int show_rcugp(struct seq_file *m, void *unused)
 342 {
 343         struct rcu_state *rsp;
 344
 345         for_each_rcu_flavor(rsp)
 346                 show_one_rcugp(m, rsp);
 347         return 0;
 348 }
 349
 350 static int rcugp_open(struct inode *inode, struct file *file)
 351 {
 352         return single_open(file, show_rcugp, NULL);
 353 }
 354
 355 static const struct file_operations rcugp_fops = {
 356         .owner = THIS_MODULE,
 357         .open = rcugp_open,
 358         .read = seq_read,
 359         .llseek = seq_lseek,
 360         .release = single_release,
 361 };
 362
 363 static int new_show_rcugp(struct seq_file *m, void *v)
 364 {
 365         struct rcu_state *rsp = (struct rcu_state *)m->private;
 366         show_one_rcugp(m, rsp);
 367         return 0;
 368 }
 369
 370 static int new_rcugp_open(struct inode *inode, struct file *file)
 371 {
 372         return single_open(file, new_show_rcugp, inode->i_private);
 373 }
 374
 375 static const struct file_operations new_rcugp_fops = {
 376         .owner = THIS_MODULE,
 377         .open = new_rcugp_open,
 378         .read = seq_read,
 379         .llseek = no_llseek,
 380         .release = seq_release,
 381 };
 382
 383 static void print_one_rcu_pending(struct seq_file *m, struct rcu_data *rdp)
 384 {
 385         if (!rdp->beenonline)
 386                 return;
 387         seq_printf(m, "%3d%cnp=%ld ",
 388                    rdp->cpu,
 389                    cpu_is_offline(rdp->cpu) ? '!' : ' ',
 390                    rdp->n_rcu_pending);
 391         seq_printf(m, "qsp=%ld rpq=%ld cbr=%ld cng=%ld ",
 392                    rdp->n_rp_qs_pending,
 393                    rdp->n_rp_report_qs,
 394                    rdp->n_rp_cb_ready,
 395                    rdp->n_rp_cpu_needs_gp);
 396         seq_printf(m, "gpc=%ld gps=%ld nn=%ld\n",
 397                    rdp->n_rp_gp_completed,
 398                    rdp->n_rp_gp_started,
 399                    rdp->n_rp_need_nothing);
 400 }
 401
 402 static int show_rcu_pending(struct seq_file *m, void *v)
 403 {
 404         print_one_rcu_pending(m, (struct rcu_data *)v);
 405         return 0;
 406 }
 407
 408 static const struct seq_operations rcu_pending_op = {
 409         .start = r_start,
 410         .next  = r_next,
 411         .stop  = r_stop,
 412         .show  = show_rcu_pending,
 413 };
 414
 415 static int rcu_pending_open(struct inode *inode, struct file *file)
 416 {
 417         return r_open(inode, file, &rcu_pending_op);
 418 }
 419
 420 static const struct file_operations rcu_pending_fops = {
 421         .owner = THIS_MODULE,
 422         .open = rcu_pending_open,
 423         .read = seq_read,
 424         .llseek = no_llseek,
 425         .release = seq_release,
 426 };
 427
 428 static int show_rcutorture(struct seq_file *m, void *unused)
 429 {
 430         seq_printf(m, "rcutorture test sequence: %lu %s\n",
 431                    rcutorture_testseq >> 1,
 432                    (rcutorture_testseq & 0x1) ? "(test in progress)" : "");
 433         seq_printf(m, "rcutorture update version number: %lu\n",
 434                    rcutorture_vernum);
 435         return 0;
 436 }
 437
 438 static int rcutorture_open(struct inode *inode, struct file *file)
 439 {
 440         return single_open(file, show_rcutorture, NULL);
 441 }
 442
 443 static const struct file_operations rcutorture_fops = {
 444         .owner = THIS_MODULE,
 445         .open = rcutorture_open,
 446         .read = seq_read,
 447         .llseek = seq_lseek,
 448         .release = single_release,
 449 };
 450
 451 static struct dentry *rcudir;
 452
 453 static int __init rcutree_trace_init(void)
 454 {
 455         struct rcu_state *rsp;
 456         struct dentry *retval;
 457         struct dentry *rspdir;
 458
 459         rcudir = debugfs_create_dir("rcu", NULL);
 460         if (!rcudir)
 461                 goto free_out;
 462
 463         for_each_rcu_flavor(rsp) {
 464                 rspdir = debugfs_create_dir(rsp->name, rcudir);
 465                 if (!rspdir)
 466                         goto free_out;
 467
 468                         retval = debugfs_create_file("rcudata", 0444,
 469                                         rspdir, rsp, &rcudata_fops);
 470                         if (!retval)
 471                                 goto free_out;
 472
 473                         retval = debugfs_create_file("rcu_pending", 0444,
 474                                         rspdir, rsp, &rcu_pending_fops);
 475                         if (!retval)
 476                                 goto free_out;
 477
 478                         retval = debugfs_create_file("rcubarrier", 0444,
 479                                         rspdir, rsp, &new_rcubarrier_fops);
 480                         if (!retval)
 481                                 goto free_out;
 482
 483 #ifdef CONFIG_RCU_BOOST
 484                         if (rsp == &rcu_preempt_state) {
 485                                 retval = debugfs_create_file("rcuboost", 0444,
 486                                         rspdir, NULL, &rcu_node_boost_fops);
 487                                 if (!retval)
 488                                         goto free_out;
 489                         }
 490 #endif
 491
 492                         retval = debugfs_create_file("rcugp", 0444,
 493                                         rspdir, rsp, &new_rcugp_fops);
 494                         if (!retval)
 495                                 goto free_out;
 496
 497         }
 498
 499         retval = debugfs_create_file("rcubarrier", 0444, rcudir,
 500                                                 NULL, &rcubarrier_fops);
 501         if (!retval)
 502                 goto free_out;
 503
 504         if (rcu_boost_trace_create_file(rcudir))
 505                 goto free_out;
 506
 507         retval = debugfs_create_file("rcugp", 0444, rcudir, NULL, &rcugp_fops);
 508         if (!retval)
 509                 goto free_out;
 510
 511         retval = debugfs_create_file("rcuhier", 0444, rcudir,
 512                                                 NULL, &rcuhier_fops);
 513         if (!retval)
 514                 goto free_out;
 515
 516         retval = debugfs_create_file("rcutorture", 0444, rcudir,
 517                                                 NULL, &rcutorture_fops);
 518         if (!retval)
 519                 goto free_out;
 520         return 0;
 521 free_out:
 522         debugfs_remove_recursive(rcudir);
 523         return 1;
 524 }
 525
 526 static void __exit rcutree_trace_cleanup(void)
 527 {
 528         debugfs_remove_recursive(rcudir);
 529 }
 530
 531
 532 module_init(rcutree_trace_init);
 533 module_exit(rcutree_trace_cleanup);
 534
 535 MODULE_AUTHOR("Paul E. McKenney");
 536 MODULE_DESCRIPTION("Read-Copy Update tracing for hierarchical implementation");
 537 MODULE_LICENSE("GPL");