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
  45 #define RCU_TREE_NONCORE
  46 #include "tree.h"
  47
  48 DECLARE_PER_CPU_SHARED_ALIGNED(unsigned long, rcu_qs_ctr);
  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(rcu_qs_ctr, rdp->cpu),
 125                    rdp->core_needs_qs);
 126         seq_printf(m, " dt=%d/%llx/%d df=%lu",
 127                    atomic_read(&rdp->dynticks->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 += rdp->qlen_lazy;
 134         ql += rdp->qlen;
 135         seq_printf(m, " ql=%ld/%ld qs=%c%c%c%c",
 136                    qll, ql,
 137                    ".N"[rdp->nxttail[RCU_NEXT_READY_TAIL] !=
 138                         rdp->nxttail[RCU_NEXT_TAIL]],
 139                    ".R"[rdp->nxttail[RCU_WAIT_TAIL] !=
 140                         rdp->nxttail[RCU_NEXT_READY_TAIL]],
 141                    ".W"[rdp->nxttail[RCU_DONE_TAIL] !=
 142                         rdp->nxttail[RCU_WAIT_TAIL]],
 143                    ".D"[&rdp->nxtlist != rdp->nxttail[RCU_DONE_TAIL]]);
 144 #ifdef CONFIG_RCU_BOOST
 145         seq_printf(m, " kt=%d/%c ktl=%x",
 146                    per_cpu(rcu_cpu_has_work, rdp->cpu),
 147                    convert_kthread_status(per_cpu(rcu_cpu_kthread_status,
 148                                           rdp->cpu)),
 149                    per_cpu(rcu_cpu_kthread_loops, rdp->cpu) & 0xffff);
 150 #endif /* #ifdef CONFIG_RCU_BOOST */
 151         seq_printf(m, " b=%ld", rdp->blimit);
 152         seq_printf(m, " ci=%lu nci=%lu co=%lu ca=%lu\n",
 153                    rdp->n_cbs_invoked, rdp->n_nocbs_invoked,
 154                    rdp->n_cbs_orphaned, rdp->n_cbs_adopted);
 155 }
 156
 157 static int show_rcudata(struct seq_file *m, void *v)
 158 {
 159         print_one_rcu_data(m, (struct rcu_data *)v);
 160         return 0;
 161 }
 162
 163 static const struct seq_operations rcudate_op = {
 164         .start = r_start,
 165         .next  = r_next,
 166         .stop  = r_stop,
 167         .show  = show_rcudata,
 168 };
 169
 170 static int rcudata_open(struct inode *inode, struct file *file)
 171 {
 172         return r_open(inode, file, &rcudate_op);
 173 }
 174
 175 static const struct file_operations rcudata_fops = {
 176         .owner = THIS_MODULE,
 177         .open = rcudata_open,
 178         .read = seq_read,
 179         .llseek = no_llseek,
 180         .release = seq_release,
 181 };
 182
 183 static int show_rcuexp(struct seq_file *m, void *v)
 184 {
 185         int cpu;
 186         struct rcu_state *rsp = (struct rcu_state *)m->private;
 187         struct rcu_data *rdp;
 188         unsigned long s0 = 0, s1 = 0, s2 = 0, s3 = 0;
 189
 190         for_each_possible_cpu(cpu) {
 191                 rdp = per_cpu_ptr(rsp->rda, cpu);
 192                 s0 += atomic_long_read(&rdp->exp_workdone0);
 193                 s1 += atomic_long_read(&rdp->exp_workdone1);
 194                 s2 += atomic_long_read(&rdp->exp_workdone2);
 195                 s3 += atomic_long_read(&rdp->exp_workdone3);
 196         }
 197         seq_printf(m, "s=%lu wd0=%lu wd1=%lu wd2=%lu wd3=%lu n=%lu enq=%d sc=%lu\n",
 198                    rsp->expedited_sequence, s0, s1, s2, s3,
 199                    atomic_long_read(&rsp->expedited_normal),
 200                    atomic_read(&rsp->expedited_need_qs),
 201                    rsp->expedited_sequence / 2);
 202         return 0;
 203 }
 204
 205 static int rcuexp_open(struct inode *inode, struct file *file)
 206 {
 207         return single_open(file, show_rcuexp, inode->i_private);
 208 }
 209
 210 static const struct file_operations rcuexp_fops = {
 211         .owner = THIS_MODULE,
 212         .open = rcuexp_open,
 213         .read = seq_read,
 214         .llseek = no_llseek,
 215         .release = single_release,
 216 };
 217
 218 #ifdef CONFIG_RCU_BOOST
 219
 220 static void print_one_rcu_node_boost(struct seq_file *m, struct rcu_node *rnp)
 221 {
 222         seq_printf(m, "%d:%d tasks=%c%c%c%c kt=%c ntb=%lu neb=%lu nnb=%lu ",
 223                    rnp->grplo, rnp->grphi,
 224                    "T."[list_empty(&rnp->blkd_tasks)],
 225                    "N."[!rnp->gp_tasks],
 226                    "E."[!rnp->exp_tasks],
 227                    "B."[!rnp->boost_tasks],
 228                    convert_kthread_status(rnp->boost_kthread_status),
 229                    rnp->n_tasks_boosted, rnp->n_exp_boosts,
 230                    rnp->n_normal_boosts);
 231         seq_printf(m, "j=%04x bt=%04x\n",
 232                    (int)(jiffies & 0xffff),
 233                    (int)(rnp->boost_time & 0xffff));
 234         seq_printf(m, "    balk: nt=%lu egt=%lu bt=%lu nb=%lu ny=%lu nos=%lu\n",
 235                    rnp->n_balk_blkd_tasks,
 236                    rnp->n_balk_exp_gp_tasks,
 237                    rnp->n_balk_boost_tasks,
 238                    rnp->n_balk_notblocked,
 239                    rnp->n_balk_notyet,
 240                    rnp->n_balk_nos);
 241 }
 242
 243 static int show_rcu_node_boost(struct seq_file *m, void *unused)
 244 {
 245         struct rcu_node *rnp;
 246
 247         rcu_for_each_leaf_node(&rcu_preempt_state, rnp)
 248                 print_one_rcu_node_boost(m, rnp);
 249         return 0;
 250 }
 251
 252 static int rcu_node_boost_open(struct inode *inode, struct file *file)
 253 {
 254         return single_open(file, show_rcu_node_boost, NULL);
 255 }
 256
 257 static const struct file_operations rcu_node_boost_fops = {
 258         .owner = THIS_MODULE,
 259         .open = rcu_node_boost_open,
 260         .read = seq_read,
 261         .llseek = no_llseek,
 262         .release = single_release,
 263 };
 264
 265 #endif /* #ifdef CONFIG_RCU_BOOST */
 266
 267 static void print_one_rcu_state(struct seq_file *m, struct rcu_state *rsp)
 268 {
 269         unsigned long gpnum;
 270         int level = 0;
 271         struct rcu_node *rnp;
 272
 273         gpnum = rsp->gpnum;
 274         seq_printf(m, "c=%ld g=%ld s=%d jfq=%ld j=%x ",
 275                    ulong2long(rsp->completed), ulong2long(gpnum),
 276                    rsp->gp_state,
 277                    (long)(rsp->jiffies_force_qs - jiffies),
 278                    (int)(jiffies & 0xffff));
 279         seq_printf(m, "nfqs=%lu/nfqsng=%lu(%lu) fqlh=%lu oqlen=%ld/%ld\n",
 280                    rsp->n_force_qs, rsp->n_force_qs_ngp,
 281                    rsp->n_force_qs - rsp->n_force_qs_ngp,
 282                    READ_ONCE(rsp->n_force_qs_lh), rsp->qlen_lazy, rsp->qlen);
 283         for (rnp = &rsp->node[0]; rnp - &rsp->node[0] < rcu_num_nodes; rnp++) {
 284                 if (rnp->level != level) {
 285                         seq_puts(m, "\n");
 286                         level = rnp->level;
 287                 }
 288                 seq_printf(m, "%lx/%lx->%lx %c%c>%c %d:%d ^%d    ",
 289                            rnp->qsmask, rnp->qsmaskinit, rnp->qsmaskinitnext,
 290                            ".G"[rnp->gp_tasks != NULL],
 291                            ".E"[rnp->exp_tasks != NULL],
 292                            ".T"[!list_empty(&rnp->blkd_tasks)],
 293                            rnp->grplo, rnp->grphi, rnp->grpnum);
 294         }
 295         seq_puts(m, "\n");
 296 }
 297
 298 static int show_rcuhier(struct seq_file *m, void *v)
 299 {
 300         struct rcu_state *rsp = (struct rcu_state *)m->private;
 301         print_one_rcu_state(m, rsp);
 302         return 0;
 303 }
 304
 305 static int rcuhier_open(struct inode *inode, struct file *file)
 306 {
 307         return single_open(file, show_rcuhier, inode->i_private);
 308 }
 309
 310 static const struct file_operations rcuhier_fops = {
 311         .owner = THIS_MODULE,
 312         .open = rcuhier_open,
 313         .read = seq_read,
 314         .llseek = no_llseek,
 315         .release = single_release,
 316 };
 317
 318 static void show_one_rcugp(struct seq_file *m, struct rcu_state *rsp)
 319 {
 320         unsigned long flags;
 321         unsigned long completed;
 322         unsigned long gpnum;
 323         unsigned long gpage;
 324         unsigned long gpmax;
 325         struct rcu_node *rnp = &rsp->node[0];
 326
 327         raw_spin_lock_irqsave_rcu_node(rnp, flags);
 328         completed = READ_ONCE(rsp->completed);
 329         gpnum = READ_ONCE(rsp->gpnum);
 330         if (completed == gpnum)
 331                 gpage = 0;
 332         else
 333                 gpage = jiffies - rsp->gp_start;
 334         gpmax = rsp->gp_max;
 335         raw_spin_unlock_irqrestore(&rnp->lock, flags);
 336         seq_printf(m, "completed=%ld  gpnum=%ld  age=%ld  max=%ld\n",
 337                    ulong2long(completed), ulong2long(gpnum), gpage, gpmax);
 338 }
 339
 340 static int show_rcugp(struct seq_file *m, void *v)
 341 {
 342         struct rcu_state *rsp = (struct rcu_state *)m->private;
 343         show_one_rcugp(m, rsp);
 344         return 0;
 345 }
 346
 347 static int rcugp_open(struct inode *inode, struct file *file)
 348 {
 349         return single_open(file, show_rcugp, inode->i_private);
 350 }
 351
 352 static const struct file_operations rcugp_fops = {
 353         .owner = THIS_MODULE,
 354         .open = rcugp_open,
 355         .read = seq_read,
 356         .llseek = no_llseek,
 357         .release = single_release,
 358 };
 359
 360 static void print_one_rcu_pending(struct seq_file *m, struct rcu_data *rdp)
 361 {
 362         if (!rdp->beenonline)
 363                 return;
 364         seq_printf(m, "%3d%cnp=%ld ",
 365                    rdp->cpu,
 366                    cpu_is_offline(rdp->cpu) ? '!' : ' ',
 367                    rdp->n_rcu_pending);
 368         seq_printf(m, "qsp=%ld rpq=%ld cbr=%ld cng=%ld ",
 369                    rdp->n_rp_core_needs_qs,
 370                    rdp->n_rp_report_qs,
 371                    rdp->n_rp_cb_ready,
 372                    rdp->n_rp_cpu_needs_gp);
 373         seq_printf(m, "gpc=%ld gps=%ld nn=%ld ndw%ld\n",
 374                    rdp->n_rp_gp_completed,
 375                    rdp->n_rp_gp_started,
 376                    rdp->n_rp_nocb_defer_wakeup,
 377                    rdp->n_rp_need_nothing);
 378 }
 379
 380 static int show_rcu_pending(struct seq_file *m, void *v)
 381 {
 382         print_one_rcu_pending(m, (struct rcu_data *)v);
 383         return 0;
 384 }
 385
 386 static const struct seq_operations rcu_pending_op = {
 387         .start = r_start,
 388         .next  = r_next,
 389         .stop  = r_stop,
 390         .show  = show_rcu_pending,
 391 };
 392
 393 static int rcu_pending_open(struct inode *inode, struct file *file)
 394 {
 395         return r_open(inode, file, &rcu_pending_op);
 396 }
 397
 398 static const struct file_operations rcu_pending_fops = {
 399         .owner = THIS_MODULE,
 400         .open = rcu_pending_open,
 401         .read = seq_read,
 402         .llseek = no_llseek,
 403         .release = seq_release,
 404 };
 405
 406 static int show_rcutorture(struct seq_file *m, void *unused)
 407 {
 408         seq_printf(m, "rcutorture test sequence: %lu %s\n",
 409                    rcutorture_testseq >> 1,
 410                    (rcutorture_testseq & 0x1) ? "(test in progress)" : "");
 411         seq_printf(m, "rcutorture update version number: %lu\n",
 412                    rcutorture_vernum);
 413         return 0;
 414 }
 415
 416 static int rcutorture_open(struct inode *inode, struct file *file)
 417 {
 418         return single_open(file, show_rcutorture, NULL);
 419 }
 420
 421 static const struct file_operations rcutorture_fops = {
 422         .owner = THIS_MODULE,
 423         .open = rcutorture_open,
 424         .read = seq_read,
 425         .llseek = seq_lseek,
 426         .release = single_release,
 427 };
 428
 429 static struct dentry *rcudir;
 430
 431 static int __init rcutree_trace_init(void)
 432 {
 433         struct rcu_state *rsp;
 434         struct dentry *retval;
 435         struct dentry *rspdir;
 436
 437         rcudir = debugfs_create_dir("rcu", NULL);
 438         if (!rcudir)
 439                 goto free_out;
 440
 441         for_each_rcu_flavor(rsp) {
 442                 rspdir = debugfs_create_dir(rsp->name, rcudir);
 443                 if (!rspdir)
 444                         goto free_out;
 445
 446                 retval = debugfs_create_file("rcudata", 0444,
 447                                 rspdir, rsp, &rcudata_fops);
 448                 if (!retval)
 449                         goto free_out;
 450
 451                 retval = debugfs_create_file("rcuexp", 0444,
 452                                 rspdir, rsp, &rcuexp_fops);
 453                 if (!retval)
 454                         goto free_out;
 455
 456                 retval = debugfs_create_file("rcu_pending", 0444,
 457                                 rspdir, rsp, &rcu_pending_fops);
 458                 if (!retval)
 459                         goto free_out;
 460
 461                 retval = debugfs_create_file("rcubarrier", 0444,
 462                                 rspdir, rsp, &rcubarrier_fops);
 463                 if (!retval)
 464                         goto free_out;
 465
 466 #ifdef CONFIG_RCU_BOOST
 467                 if (rsp == &rcu_preempt_state) {
 468                         retval = debugfs_create_file("rcuboost", 0444,
 469                                 rspdir, NULL, &rcu_node_boost_fops);
 470                         if (!retval)
 471                                 goto free_out;
 472                 }
 473 #endif
 474
 475                 retval = debugfs_create_file("rcugp", 0444,
 476                                 rspdir, rsp, &rcugp_fops);
 477                 if (!retval)
 478                         goto free_out;
 479
 480                 retval = debugfs_create_file("rcuhier", 0444,
 481                                 rspdir, rsp, &rcuhier_fops);
 482                 if (!retval)
 483                         goto free_out;
 484         }
 485
 486         retval = debugfs_create_file("rcutorture", 0444, rcudir,
 487                                                 NULL, &rcutorture_fops);
 488         if (!retval)
 489                 goto free_out;
 490         return 0;
 491 free_out:
 492         debugfs_remove_recursive(rcudir);
 493         return 1;
 494 }
 495 device_initcall(rcutree_trace_init);