kernel/rcu/tree_trace.c

   1 /*
   2  * Read-Copy Update tracing for hierarchical 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  * Author: Paul E. McKenney
  20  *
  21  * Papers:  http://www.rdrop.com/users/paulmck/RCU
  22  *
  23  * For detailed explanation of Read-Copy Update mechanism see -
  24  *              Documentation/RCU
  25  *
  26  */
  27 #include <linux/types.h>
  28 #include <linux/kernel.h>
  29 #include <linux/init.h>
  30 #include <linux/spinlock.h>
  31 #include <linux/smp.h>
  32 #include <linux/rcupdate.h>
  33 #include <linux/interrupt.h>
  34 #include <linux/sched.h>
  35 #include <linux/atomic.h>
  36 #include <linux/bitops.h>
  37 #include <linux/completion.h>
  38 #include <linux/percpu.h>
  39 #include <linux/notifier.h>
  40 #include <linux/cpu.h>
  41 #include <linux/mutex.h>
  42 #include <linux/debugfs.h>
  43 #include <linux/seq_file.h>
  44 #include <linux/prefetch.h>
  45
  46 #define RCU_TREE_NONCORE
  47 #include "tree.h"
  48 #include "rcu.h"
  49
  50 static int r_open(struct inode *inode, struct file *file,
  51                                         const struct seq_operations *op)
  52 {
  53         int ret = seq_open(file, op);
  54         if (!ret) {
  55                 struct seq_file *m = (struct seq_file *)file->private_data;
  56                 m->private = inode->i_private;
  57         }
  58         return ret;
  59 }
  60
  61 static void *r_start(struct seq_file *m, loff_t *pos)
  62 {
  63         struct rcu_state *rsp = (struct rcu_state *)m->private;
  64         *pos = cpumask_next(*pos - 1, cpu_possible_mask);
  65         if ((*pos) < nr_cpu_ids)
  66                 return per_cpu_ptr(rsp->rda, *pos);
  67         return NULL;
  68 }
  69
  70 static void *r_next(struct seq_file *m, void *v, loff_t *pos)
  71 {
  72         (*pos)++;
  73         return r_start(m, pos);
  74 }
  75
  76 static void r_stop(struct seq_file *m, void *v)
  77 {
  78 }
  79
  80 static int show_rcubarrier(struct seq_file *m, void *v)
  81 {
  82         struct rcu_state *rsp = (struct rcu_state *)m->private;
  83         seq_printf(m, "bcc: %d bseq: %lu\n",
  84                    atomic_read(&rsp->barrier_cpu_count),
  85                    rsp->barrier_sequence);
  86         return 0;
  87 }
  88
  89 static int rcubarrier_open(struct inode *inode, struct file *file)
  90 {
  91         return single_open(file, show_rcubarrier, inode->i_private);
  92 }
  93
  94 static const struct file_operations rcubarrier_fops = {
  95         .owner = THIS_MODULE,
  96         .open = rcubarrier_open,
  97         .read = seq_read,
  98         .llseek = no_llseek,
  99         .release = single_release,
 100 };
 101
 102 #ifdef CONFIG_RCU_BOOST
 103
 104 static char convert_kthread_status(unsigned int kthread_status)
 105 {
 106         if (kthread_status > RCU_KTHREAD_MAX)
 107                 return '?';
 108         return "SRWOY"[kthread_status];
 109 }
 110
 111 #endif /* #ifdef CONFIG_RCU_BOOST */
 112
 113 static void print_one_rcu_data(struct seq_file *m, struct rcu_data *rdp)
 114 {
 115         long ql, qll;
 116
 117         if (!rdp->beenonline)
 118                 return;
 119         seq_printf(m, "%3d%cc=%ld g=%ld cnq=%d/%d:%d",
 120                    rdp->cpu,
 121                    cpu_is_offline(rdp->cpu) ? '!' : ' ',
 122                    ulong2long(rdp->completed), ulong2long(rdp->gpnum),
 123                    rdp->cpu_no_qs.b.norm,
 124                    rdp->rcu_qs_ctr_snap == per_cpu(rdp->dynticks->rcu_qs_ctr, rdp->cpu),
 125                    rdp->core_needs_qs);
 126         seq_printf(m, " dt=%d/%llx/%d df=%lu",
 127                    rcu_dynticks_snap(rdp->dynticks),
 128                    rdp->dynticks->dynticks_nesting,
 129                    rdp->dynticks->dynticks_nmi_nesting,
 130                    rdp->dynticks_fqs);
 131         seq_printf(m, " of=%lu", rdp->offline_fqs);
 132         rcu_nocb_q_lengths(rdp, &ql, &qll);
 133         qll += rcu_segcblist_n_lazy_cbs(&rdp->cblist);
 134         ql += rcu_segcblist_n_cbs(&rdp->cblist);
 135         seq_printf(m, " ql=%ld/%ld qs=%c%c%c%c",
 136                    qll, ql,
 137                    ".N"[!rcu_segcblist_segempty(&rdp->cblist, RCU_NEXT_TAIL)],
 138                    ".R"[!rcu_segcblist_segempty(&rdp->cblist,
 139                                                 RCU_NEXT_READY_TAIL)],
 140                    ".W"[!rcu_segcblist_segempty(&rdp->cblist, RCU_WAIT_TAIL)],
 141                    ".D"[!rcu_segcblist_segempty(&rdp->cblist, RCU_DONE_TAIL)]);
 142 #ifdef CONFIG_RCU_BOOST
 143         seq_printf(m, " kt=%d/%c ktl=%x",
 144                    per_cpu(rcu_cpu_has_work, rdp->cpu),
 145                    convert_kthread_status(per_cpu(rcu_cpu_kthread_status,
 146                                           rdp->cpu)),
 147                    per_cpu(rcu_cpu_kthread_loops, rdp->cpu) & 0xffff);
 148 #endif /* #ifdef CONFIG_RCU_BOOST */
 149         seq_printf(m, " b=%ld", rdp->blimit);
 150         seq_printf(m, " ci=%lu nci=%lu co=%lu ca=%lu\n",
 151                    rdp->n_cbs_invoked, rdp->n_nocbs_invoked,
 152                    rdp->n_cbs_orphaned, rdp->n_cbs_adopted);
 153 }
 154
 155 static int show_rcudata(struct seq_file *m, void *v)
 156 {
 157         print_one_rcu_data(m, (struct rcu_data *)v);
 158         return 0;
 159 }
 160
 161 static const struct seq_operations rcudate_op = {
 162         .start = r_start,
 163         .next  = r_next,
 164         .stop  = r_stop,
 165         .show  = show_rcudata,
 166 };
 167
 168 static int rcudata_open(struct inode *inode, struct file *file)
 169 {
 170         return r_open(inode, file, &rcudate_op);
 171 }
 172
 173 static const struct file_operations rcudata_fops = {
 174         .owner = THIS_MODULE,
 175         .open = rcudata_open,
 176         .read = seq_read,
 177         .llseek = no_llseek,
 178         .release = seq_release,
 179 };
 180
 181 static int show_rcuexp(struct seq_file *m, void *v)
 182 {
 183         int cpu;
 184         struct rcu_state *rsp = (struct rcu_state *)m->private;
 185         struct rcu_data *rdp;
 186         unsigned long s0 = 0, s1 = 0, s2 = 0, s3 = 0;
 187
 188         for_each_possible_cpu(cpu) {
 189                 rdp = per_cpu_ptr(rsp->rda, cpu);
 190                 s0 += atomic_long_read(&rdp->exp_workdone0);
 191                 s1 += atomic_long_read(&rdp->exp_workdone1);
 192                 s2 += atomic_long_read(&rdp->exp_workdone2);
 193                 s3 += atomic_long_read(&rdp->exp_workdone3);
 194         }
 195         seq_printf(m, "s=%lu wd0=%lu wd1=%lu wd2=%lu wd3=%lu enq=%d sc=%lu\n",
 196                    rsp->expedited_sequence, s0, s1, s2, s3,
 197                    atomic_read(&rsp->expedited_need_qs),
 198                    rsp->expedited_sequence / 2);
 199         return 0;
 200 }
 201
 202 static int rcuexp_open(struct inode *inode, struct file *file)
 203 {
 204         return single_open(file, show_rcuexp, inode->i_private);
 205 }
 206
 207 static const struct file_operations rcuexp_fops = {
 208         .owner = THIS_MODULE,
 209         .open = rcuexp_open,
 210         .read = seq_read,
 211         .llseek = no_llseek,
 212         .release = single_release,
 213 };
 214
 215 #ifdef CONFIG_RCU_BOOST
 216
 217 static void print_one_rcu_node_boost(struct seq_file *m, struct rcu_node *rnp)
 218 {
 219         seq_printf(m, "%d:%d tasks=%c%c%c%c kt=%c ntb=%lu neb=%lu nnb=%lu ",
 220                    rnp->grplo, rnp->grphi,
 221                    "T."[list_empty(&rnp->blkd_tasks)],
 222                    "N."[!rnp->gp_tasks],
 223                    "E."[!rnp->exp_tasks],
 224                    "B."[!rnp->boost_tasks],
 225                    convert_kthread_status(rnp->boost_kthread_status),
 226                    rnp->n_tasks_boosted, rnp->n_exp_boosts,
 227                    rnp->n_normal_boosts);
 228         seq_printf(m, "j=%04x bt=%04x\n",
 229                    (int)(jiffies & 0xffff),
 230                    (int)(rnp->boost_time & 0xffff));
 231         seq_printf(m, "    balk: nt=%lu egt=%lu bt=%lu nb=%lu ny=%lu nos=%lu\n",
 232                    rnp->n_balk_blkd_tasks,
 233                    rnp->n_balk_exp_gp_tasks,
 234                    rnp->n_balk_boost_tasks,
 235                    rnp->n_balk_notblocked,
 236                    rnp->n_balk_notyet,
 237                    rnp->n_balk_nos);
 238 }
 239
 240 static int show_rcu_node_boost(struct seq_file *m, void *unused)
 241 {
 242         struct rcu_node *rnp;
 243
 244         rcu_for_each_leaf_node(&rcu_preempt_state, rnp)
 245                 print_one_rcu_node_boost(m, rnp);
 246         return 0;
 247 }
 248
 249 static int rcu_node_boost_open(struct inode *inode, struct file *file)
 250 {
 251         return single_open(file, show_rcu_node_boost, NULL);
 252 }
 253
 254 static const struct file_operations rcu_node_boost_fops = {
 255         .owner = THIS_MODULE,
 256         .open = rcu_node_boost_open,
 257         .read = seq_read,
 258         .llseek = no_llseek,
 259         .release = single_release,
 260 };
 261
 262 #endif /* #ifdef CONFIG_RCU_BOOST */
 263
 264 static void print_one_rcu_state(struct seq_file *m, struct rcu_state *rsp)
 265 {
 266         unsigned long gpnum;
 267         int level = 0;
 268         struct rcu_node *rnp;
 269
 270         gpnum = rsp->gpnum;
 271         seq_printf(m, "c=%ld g=%ld s=%d jfq=%ld j=%x ",
 272                    ulong2long(rsp->completed), ulong2long(gpnum),
 273                    rsp->gp_state,
 274                    (long)(rsp->jiffies_force_qs - jiffies),
 275                    (int)(jiffies & 0xffff));
 276         seq_printf(m, "nfqs=%lu/nfqsng=%lu(%lu) fqlh=%lu oqlen=%ld/%ld\n",
 277                    rsp->n_force_qs, rsp->n_force_qs_ngp,
 278                    rsp->n_force_qs - rsp->n_force_qs_ngp,
 279                    READ_ONCE(rsp->n_force_qs_lh),
 280                    rsp->orphan_done.len_lazy,
 281                    rsp->orphan_done.len);
 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->%lx %c%c>%c %d:%d ^%d    ",
 288                            rnp->qsmask, rnp->qsmaskinit, rnp->qsmaskinitnext,
 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 *v)
 298 {
 299         struct rcu_state *rsp = (struct rcu_state *)m->private;
 300         print_one_rcu_state(m, rsp);
 301         return 0;
 302 }
 303
 304 static int rcuhier_open(struct inode *inode, struct file *file)
 305 {
 306         return single_open(file, show_rcuhier, inode->i_private);
 307 }
 308
 309 static const struct file_operations rcuhier_fops = {
 310         .owner = THIS_MODULE,
 311         .open = rcuhier_open,
 312         .read = seq_read,
 313         .llseek = no_llseek,
 314         .release = single_release,
 315 };
 316
 317 static void show_one_rcugp(struct seq_file *m, struct rcu_state *rsp)
 318 {
 319         unsigned long flags;
 320         unsigned long completed;
 321         unsigned long gpnum;
 322         unsigned long gpage;
 323         unsigned long gpmax;
 324         struct rcu_node *rnp = &rsp->node[0];
 325
 326         raw_spin_lock_irqsave_rcu_node(rnp, flags);
 327         completed = READ_ONCE(rsp->completed);
 328         gpnum = READ_ONCE(rsp->gpnum);
 329         if (completed == gpnum)
 330                 gpage = 0;
 331         else
 332                 gpage = jiffies - rsp->gp_start;
 333         gpmax = rsp->gp_max;
 334         raw_spin_unlock_irqrestore(&rnp->lock, flags);
 335         seq_printf(m, "completed=%ld  gpnum=%ld  age=%ld  max=%ld\n",
 336                    ulong2long(completed), ulong2long(gpnum), gpage, gpmax);
 337 }
 338
 339 static int show_rcugp(struct seq_file *m, void *v)
 340 {
 341         struct rcu_state *rsp = (struct rcu_state *)m->private;
 342         show_one_rcugp(m, rsp);
 343         return 0;
 344 }
 345
 346 static int rcugp_open(struct inode *inode, struct file *file)
 347 {
 348         return single_open(file, show_rcugp, inode->i_private);
 349 }
 350
 351 static const struct file_operations rcugp_fops = {
 352         .owner = THIS_MODULE,
 353         .open = rcugp_open,
 354         .read = seq_read,
 355         .llseek = no_llseek,
 356         .release = single_release,
 357 };
 358
 359 static void print_one_rcu_pending(struct seq_file *m, struct rcu_data *rdp)
 360 {
 361         if (!rdp->beenonline)
 362                 return;
 363         seq_printf(m, "%3d%cnp=%ld ",
 364                    rdp->cpu,
 365                    cpu_is_offline(rdp->cpu) ? '!' : ' ',
 366                    rdp->n_rcu_pending);
 367         seq_printf(m, "qsp=%ld rpq=%ld cbr=%ld cng=%ld ",
 368                    rdp->n_rp_core_needs_qs,
 369                    rdp->n_rp_report_qs,
 370                    rdp->n_rp_cb_ready,
 371                    rdp->n_rp_cpu_needs_gp);
 372         seq_printf(m, "gpc=%ld gps=%ld nn=%ld ndw%ld\n",
 373                    rdp->n_rp_gp_completed,
 374                    rdp->n_rp_gp_started,
 375                    rdp->n_rp_nocb_defer_wakeup,
 376                    rdp->n_rp_need_nothing);
 377 }
 378
 379 static int show_rcu_pending(struct seq_file *m, void *v)
 380 {
 381         print_one_rcu_pending(m, (struct rcu_data *)v);
 382         return 0;
 383 }
 384
 385 static const struct seq_operations rcu_pending_op = {
 386         .start = r_start,
 387         .next  = r_next,
 388         .stop  = r_stop,
 389         .show  = show_rcu_pending,
 390 };
 391
 392 static int rcu_pending_open(struct inode *inode, struct file *file)
 393 {
 394         return r_open(inode, file, &rcu_pending_op);
 395 }
 396
 397 static const struct file_operations rcu_pending_fops = {
 398         .owner = THIS_MODULE,
 399         .open = rcu_pending_open,
 400         .read = seq_read,
 401         .llseek = no_llseek,
 402         .release = seq_release,
 403 };
 404
 405 static int show_rcutorture(struct seq_file *m, void *unused)
 406 {
 407         seq_printf(m, "rcutorture test sequence: %lu %s\n",
 408                    rcutorture_testseq >> 1,
 409                    (rcutorture_testseq & 0x1) ? "(test in progress)" : "");
 410         seq_printf(m, "rcutorture update version number: %lu\n",
 411                    rcutorture_vernum);
 412         return 0;
 413 }
 414
 415 static int rcutorture_open(struct inode *inode, struct file *file)
 416 {
 417         return single_open(file, show_rcutorture, NULL);
 418 }
 419
 420 static const struct file_operations rcutorture_fops = {
 421         .owner = THIS_MODULE,
 422         .open = rcutorture_open,
 423         .read = seq_read,
 424         .llseek = seq_lseek,
 425         .release = single_release,
 426 };
 427
 428 static struct dentry *rcudir;
 429
 430 static int __init rcutree_trace_init(void)
 431 {
 432         struct rcu_state *rsp;
 433         struct dentry *retval;
 434         struct dentry *rspdir;
 435
 436         rcudir = debugfs_create_dir("rcu", NULL);
 437         if (!rcudir)
 438                 goto free_out;
 439
 440         for_each_rcu_flavor(rsp) {
 441                 rspdir = debugfs_create_dir(rsp->name, rcudir);
 442                 if (!rspdir)
 443                         goto free_out;
 444
 445                 retval = debugfs_create_file("rcudata", 0444,
 446                                 rspdir, rsp, &rcudata_fops);
 447                 if (!retval)
 448                         goto free_out;
 449
 450                 retval = debugfs_create_file("rcuexp", 0444,
 451                                 rspdir, rsp, &rcuexp_fops);
 452                 if (!retval)
 453                         goto free_out;
 454
 455                 retval = debugfs_create_file("rcu_pending", 0444,
 456                                 rspdir, rsp, &rcu_pending_fops);
 457                 if (!retval)
 458                         goto free_out;
 459
 460                 retval = debugfs_create_file("rcubarrier", 0444,
 461                                 rspdir, rsp, &rcubarrier_fops);
 462                 if (!retval)
 463                         goto free_out;
 464
 465 #ifdef CONFIG_RCU_BOOST
 466                 if (rsp == &rcu_preempt_state) {
 467                         retval = debugfs_create_file("rcuboost", 0444,
 468                                 rspdir, NULL, &rcu_node_boost_fops);
 469                         if (!retval)
 470                                 goto free_out;
 471                 }
 472 #endif
 473
 474                 retval = debugfs_create_file("rcugp", 0444,
 475                                 rspdir, rsp, &rcugp_fops);
 476                 if (!retval)
 477                         goto free_out;
 478
 479                 retval = debugfs_create_file("rcuhier", 0444,
 480                                 rspdir, rsp, &rcuhier_fops);
 481                 if (!retval)
 482                         goto free_out;
 483         }
 484
 485         retval = debugfs_create_file("rcutorture", 0444, rcudir,
 486                                                 NULL, &rcutorture_fops);
 487         if (!retval)
 488                 goto free_out;
 489         return 0;
 490 free_out:
 491         debugfs_remove_recursive(rcudir);
 492         return 1;
 493 }
 494 device_initcall(rcutree_trace_init);