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 *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 = seq_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 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 co=%lu ca=%lu\n",
 152                    rdp->n_cbs_invoked, 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         struct rcu_state *rsp = (struct rcu_state *)m->private;
 184
 185         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",
 186                    atomic_long_read(&rsp->expedited_start),
 187                    atomic_long_read(&rsp->expedited_done),
 188                    atomic_long_read(&rsp->expedited_wrap),
 189                    atomic_long_read(&rsp->expedited_tryfail),
 190                    atomic_long_read(&rsp->expedited_workdone1),
 191                    atomic_long_read(&rsp->expedited_workdone2),
 192                    atomic_long_read(&rsp->expedited_normal),
 193                    atomic_long_read(&rsp->expedited_stoppedcpus),
 194                    atomic_long_read(&rsp->expedited_done_tries),
 195                    atomic_long_read(&rsp->expedited_done_lost),
 196                    atomic_long_read(&rsp->expedited_done_exit));
 197         return 0;
 198 }
 199
 200 static int rcuexp_open(struct inode *inode, struct file *file)
 201 {
 202         return single_open(file, show_rcuexp, inode->i_private);
 203 }
 204
 205 static const struct file_operations rcuexp_fops = {
 206         .owner = THIS_MODULE,
 207         .open = rcuexp_open,
 208         .read = seq_read,
 209         .llseek = no_llseek,
 210         .release = seq_release,
 211 };
 212
 213 #ifdef CONFIG_RCU_BOOST
 214
 215 static void print_one_rcu_node_boost(struct seq_file *m, struct rcu_node *rnp)
 216 {
 217         seq_printf(m, "%d:%d tasks=%c%c%c%c kt=%c ntb=%lu neb=%lu nnb=%lu ",
 218                    rnp->grplo, rnp->grphi,
 219                    "T."[list_empty(&rnp->blkd_tasks)],
 220                    "N."[!rnp->gp_tasks],
 221                    "E."[!rnp->exp_tasks],
 222                    "B."[!rnp->boost_tasks],
 223                    convert_kthread_status(rnp->boost_kthread_status),
 224                    rnp->n_tasks_boosted, rnp->n_exp_boosts,
 225                    rnp->n_normal_boosts);
 226         seq_printf(m, "j=%04x bt=%04x\n",
 227                    (int)(jiffies & 0xffff),
 228                    (int)(rnp->boost_time & 0xffff));
 229         seq_printf(m, "    balk: nt=%lu egt=%lu bt=%lu nb=%lu ny=%lu nos=%lu\n",
 230                    rnp->n_balk_blkd_tasks,
 231                    rnp->n_balk_exp_gp_tasks,
 232                    rnp->n_balk_boost_tasks,
 233                    rnp->n_balk_notblocked,
 234                    rnp->n_balk_notyet,
 235                    rnp->n_balk_nos);
 236 }
 237
 238 static int show_rcu_node_boost(struct seq_file *m, void *unused)
 239 {
 240         struct rcu_node *rnp;
 241
 242         rcu_for_each_leaf_node(&rcu_preempt_state, rnp)
 243                 print_one_rcu_node_boost(m, rnp);
 244         return 0;
 245 }
 246
 247 static int rcu_node_boost_open(struct inode *inode, struct file *file)
 248 {
 249         return single_open(file, show_rcu_node_boost, NULL);
 250 }
 251
 252 static const struct file_operations rcu_node_boost_fops = {
 253         .owner = THIS_MODULE,
 254         .open = rcu_node_boost_open,
 255         .read = seq_read,
 256         .llseek = no_llseek,
 257         .release = single_release,
 258 };
 259
 260 #endif /* #ifdef CONFIG_RCU_BOOST */
 261
 262 static void print_one_rcu_state(struct seq_file *m, struct rcu_state *rsp)
 263 {
 264         unsigned long gpnum;
 265         int level = 0;
 266         struct rcu_node *rnp;
 267
 268         gpnum = rsp->gpnum;
 269         seq_printf(m, "c=%ld g=%ld s=%d jfq=%ld j=%x ",
 270                    ulong2long(rsp->completed), ulong2long(gpnum),
 271                    rsp->fqs_state,
 272                    (long)(rsp->jiffies_force_qs - jiffies),
 273                    (int)(jiffies & 0xffff));
 274         seq_printf(m, "nfqs=%lu/nfqsng=%lu(%lu) fqlh=%lu oqlen=%ld/%ld\n",
 275                    rsp->n_force_qs, rsp->n_force_qs_ngp,
 276                    rsp->n_force_qs - rsp->n_force_qs_ngp,
 277                    rsp->n_force_qs_lh, rsp->qlen_lazy, rsp->qlen);
 278         for (rnp = &rsp->node[0]; rnp - &rsp->node[0] < rcu_num_nodes; rnp++) {
 279                 if (rnp->level != level) {
 280                         seq_puts(m, "\n");
 281                         level = rnp->level;
 282                 }
 283                 seq_printf(m, "%lx/%lx %c%c>%c %d:%d ^%d    ",
 284                            rnp->qsmask, rnp->qsmaskinit,
 285                            ".G"[rnp->gp_tasks != NULL],
 286                            ".E"[rnp->exp_tasks != NULL],
 287                            ".T"[!list_empty(&rnp->blkd_tasks)],
 288                            rnp->grplo, rnp->grphi, rnp->grpnum);
 289         }
 290         seq_puts(m, "\n");
 291 }
 292
 293 static int show_rcuhier(struct seq_file *m, void *v)
 294 {
 295         struct rcu_state *rsp = (struct rcu_state *)m->private;
 296         print_one_rcu_state(m, rsp);
 297         return 0;
 298 }
 299
 300 static int rcuhier_open(struct inode *inode, struct file *file)
 301 {
 302         return single_open(file, show_rcuhier, inode->i_private);
 303 }
 304
 305 static const struct file_operations rcuhier_fops = {
 306         .owner = THIS_MODULE,
 307         .open = rcuhier_open,
 308         .read = seq_read,
 309         .llseek = no_llseek,
 310         .release = seq_release,
 311 };
 312
 313 static void show_one_rcugp(struct seq_file *m, struct rcu_state *rsp)
 314 {
 315         unsigned long flags;
 316         unsigned long completed;
 317         unsigned long gpnum;
 318         unsigned long gpage;
 319         unsigned long gpmax;
 320         struct rcu_node *rnp = &rsp->node[0];
 321
 322         raw_spin_lock_irqsave(&rnp->lock, flags);
 323         completed = ACCESS_ONCE(rsp->completed);
 324         gpnum = ACCESS_ONCE(rsp->gpnum);
 325         if (completed == gpnum)
 326                 gpage = 0;
 327         else
 328                 gpage = jiffies - rsp->gp_start;
 329         gpmax = rsp->gp_max;
 330         raw_spin_unlock_irqrestore(&rnp->lock, flags);
 331         seq_printf(m, "completed=%ld  gpnum=%ld  age=%ld  max=%ld\n",
 332                    ulong2long(completed), ulong2long(gpnum), gpage, gpmax);
 333 }
 334
 335 static int show_rcugp(struct seq_file *m, void *v)
 336 {
 337         struct rcu_state *rsp = (struct rcu_state *)m->private;
 338         show_one_rcugp(m, rsp);
 339         return 0;
 340 }
 341
 342 static int rcugp_open(struct inode *inode, struct file *file)
 343 {
 344         return single_open(file, show_rcugp, inode->i_private);
 345 }
 346
 347 static const struct file_operations rcugp_fops = {
 348         .owner = THIS_MODULE,
 349         .open = rcugp_open,
 350         .read = seq_read,
 351         .llseek = no_llseek,
 352         .release = seq_release,
 353 };
 354
 355 static void print_one_rcu_pending(struct seq_file *m, struct rcu_data *rdp)
 356 {
 357         if (!rdp->beenonline)
 358                 return;
 359         seq_printf(m, "%3d%cnp=%ld ",
 360                    rdp->cpu,
 361                    cpu_is_offline(rdp->cpu) ? '!' : ' ',
 362                    rdp->n_rcu_pending);
 363         seq_printf(m, "qsp=%ld rpq=%ld cbr=%ld cng=%ld ",
 364                    rdp->n_rp_qs_pending,
 365                    rdp->n_rp_report_qs,
 366                    rdp->n_rp_cb_ready,
 367                    rdp->n_rp_cpu_needs_gp);
 368         seq_printf(m, "gpc=%ld gps=%ld nn=%ld\n",
 369                    rdp->n_rp_gp_completed,
 370                    rdp->n_rp_gp_started,
 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");