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