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 <asm/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 DECLARE_PER_CPU(unsigned int, rcu_cpu_kthread_status);
  50 DECLARE_PER_CPU(char, rcu_cpu_has_work);
  51
  52 static char convert_kthread_status(unsigned int kthread_status)
  53 {
  54         if (kthread_status > RCU_KTHREAD_MAX)
  55                 return '?';
  56         return "SRWY"[kthread_status];
  57 }
  58
  59 static void print_one_rcu_data(struct seq_file *m, struct rcu_data *rdp)
  60 {
  61         if (!rdp->beenonline)
  62                 return;
  63         seq_printf(m, "%3d%cc=%lu g=%lu pq=%d pqc=%lu qp=%d",
  64                    rdp->cpu,
  65                    cpu_is_offline(rdp->cpu) ? '!' : ' ',
  66                    rdp->completed, rdp->gpnum,
  67                    rdp->passed_quiesc, rdp->passed_quiesc_completed,
  68                    rdp->qs_pending);
  69 #ifdef CONFIG_NO_HZ
  70         seq_printf(m, " dt=%d/%d/%d df=%lu",
  71                    atomic_read(&rdp->dynticks->dynticks),
  72                    rdp->dynticks->dynticks_nesting,
  73                    rdp->dynticks->dynticks_nmi_nesting,
  74                    rdp->dynticks_fqs);
  75 #endif /* #ifdef CONFIG_NO_HZ */
  76         seq_printf(m, " of=%lu ri=%lu", rdp->offline_fqs, rdp->resched_ipi);
  77         seq_printf(m, " ql=%ld qs=%c%c%c%c kt=%d/%c b=%ld",
  78                    rdp->qlen,
  79                    ".N"[rdp->nxttail[RCU_NEXT_READY_TAIL] !=
  80                         rdp->nxttail[RCU_NEXT_TAIL]],
  81                    ".R"[rdp->nxttail[RCU_WAIT_TAIL] !=
  82                         rdp->nxttail[RCU_NEXT_READY_TAIL]],
  83                    ".W"[rdp->nxttail[RCU_DONE_TAIL] !=
  84                         rdp->nxttail[RCU_WAIT_TAIL]],
  85                    ".D"[&rdp->nxtlist != rdp->nxttail[RCU_DONE_TAIL]],
  86                    per_cpu(rcu_cpu_has_work, rdp->cpu),
  87                    convert_kthread_status(per_cpu(rcu_cpu_kthread_status,
  88                                           rdp->cpu)),
  89                    rdp->blimit);
  90         seq_printf(m, " ci=%lu co=%lu ca=%lu\n",
  91                    rdp->n_cbs_invoked, rdp->n_cbs_orphaned, rdp->n_cbs_adopted);
  92 }
  93
  94 #define PRINT_RCU_DATA(name, func, m) \
  95         do { \
  96                 int _p_r_d_i; \
  97                 \
  98                 for_each_possible_cpu(_p_r_d_i) \
  99                         func(m, &per_cpu(name, _p_r_d_i)); \
 100         } while (0)
 101
 102 static int show_rcudata(struct seq_file *m, void *unused)
 103 {
 104 #ifdef CONFIG_TREE_PREEMPT_RCU
 105         seq_puts(m, "rcu_preempt:\n");
 106         PRINT_RCU_DATA(rcu_preempt_data, print_one_rcu_data, m);
 107 #endif /* #ifdef CONFIG_TREE_PREEMPT_RCU */
 108         seq_puts(m, "rcu_sched:\n");
 109         PRINT_RCU_DATA(rcu_sched_data, print_one_rcu_data, m);
 110         seq_puts(m, "rcu_bh:\n");
 111         PRINT_RCU_DATA(rcu_bh_data, print_one_rcu_data, m);
 112         return 0;
 113 }
 114
 115 static int rcudata_open(struct inode *inode, struct file *file)
 116 {
 117         return single_open(file, show_rcudata, NULL);
 118 }
 119
 120 static const struct file_operations rcudata_fops = {
 121         .owner = THIS_MODULE,
 122         .open = rcudata_open,
 123         .read = seq_read,
 124         .llseek = seq_lseek,
 125         .release = single_release,
 126 };
 127
 128 static void print_one_rcu_data_csv(struct seq_file *m, struct rcu_data *rdp)
 129 {
 130         if (!rdp->beenonline)
 131                 return;
 132         seq_printf(m, "%d,%s,%lu,%lu,%d,%lu,%d",
 133                    rdp->cpu,
 134                    cpu_is_offline(rdp->cpu) ? "\"N\"" : "\"Y\"",
 135                    rdp->completed, rdp->gpnum,
 136                    rdp->passed_quiesc, rdp->passed_quiesc_completed,
 137                    rdp->qs_pending);
 138 #ifdef CONFIG_NO_HZ
 139         seq_printf(m, ",%d,%d,%d,%lu",
 140                    atomic_read(&rdp->dynticks->dynticks),
 141                    rdp->dynticks->dynticks_nesting,
 142                    rdp->dynticks->dynticks_nmi_nesting,
 143                    rdp->dynticks_fqs);
 144 #endif /* #ifdef CONFIG_NO_HZ */
 145         seq_printf(m, ",%lu,%lu", rdp->offline_fqs, rdp->resched_ipi);
 146         seq_printf(m, ",%ld,\"%c%c%c%c\",%d,\"%c\",%ld", rdp->qlen,
 147                    ".N"[rdp->nxttail[RCU_NEXT_READY_TAIL] !=
 148                         rdp->nxttail[RCU_NEXT_TAIL]],
 149                    ".R"[rdp->nxttail[RCU_WAIT_TAIL] !=
 150                         rdp->nxttail[RCU_NEXT_READY_TAIL]],
 151                    ".W"[rdp->nxttail[RCU_DONE_TAIL] !=
 152                         rdp->nxttail[RCU_WAIT_TAIL]],
 153                    ".D"[&rdp->nxtlist != rdp->nxttail[RCU_DONE_TAIL]],
 154                    per_cpu(rcu_cpu_has_work, rdp->cpu),
 155                    convert_kthread_status(per_cpu(rcu_cpu_kthread_status,
 156                                           rdp->cpu)),
 157                    rdp->blimit);
 158         seq_printf(m, ",%lu,%lu,%lu\n",
 159                    rdp->n_cbs_invoked, rdp->n_cbs_orphaned, rdp->n_cbs_adopted);
 160 }
 161
 162 static int show_rcudata_csv(struct seq_file *m, void *unused)
 163 {
 164         seq_puts(m, "\"CPU\",\"Online?\",\"c\",\"g\",\"pq\",\"pqc\",\"pq\",");
 165 #ifdef CONFIG_NO_HZ
 166         seq_puts(m, "\"dt\",\"dt nesting\",\"dt NMI nesting\",\"df\",");
 167 #endif /* #ifdef CONFIG_NO_HZ */
 168         seq_puts(m, "\"of\",\"ri\",\"ql\",\"b\",\"ci\",\"co\",\"ca\"\n");
 169 #ifdef CONFIG_TREE_PREEMPT_RCU
 170         seq_puts(m, "\"rcu_preempt:\"\n");
 171         PRINT_RCU_DATA(rcu_preempt_data, print_one_rcu_data_csv, m);
 172 #endif /* #ifdef CONFIG_TREE_PREEMPT_RCU */
 173         seq_puts(m, "\"rcu_sched:\"\n");
 174         PRINT_RCU_DATA(rcu_sched_data, print_one_rcu_data_csv, m);
 175         seq_puts(m, "\"rcu_bh:\"\n");
 176         PRINT_RCU_DATA(rcu_bh_data, print_one_rcu_data_csv, m);
 177         return 0;
 178 }
 179
 180 static int rcudata_csv_open(struct inode *inode, struct file *file)
 181 {
 182         return single_open(file, show_rcudata_csv, NULL);
 183 }
 184
 185 static const struct file_operations rcudata_csv_fops = {
 186         .owner = THIS_MODULE,
 187         .open = rcudata_csv_open,
 188         .read = seq_read,
 189         .llseek = seq_lseek,
 190         .release = single_release,
 191 };
 192
 193 #ifdef CONFIG_RCU_BOOST
 194
 195 static void print_one_rcu_node_boost(struct seq_file *m, struct rcu_node *rnp)
 196 {
 197         seq_printf(m,  "%d:%d tasks=%c%c%c%c kt=%c ntb=%lu neb=%lu nnb=%lu "
 198                    "j=%04x bt=%04x\n",
 199                    rnp->grplo, rnp->grphi,
 200                    "T."[list_empty(&rnp->blkd_tasks)],
 201                    "N."[!rnp->gp_tasks],
 202                    "E."[!rnp->exp_tasks],
 203                    "B."[!rnp->boost_tasks],
 204                    convert_kthread_status(rnp->boost_kthread_status),
 205                    rnp->n_tasks_boosted, rnp->n_exp_boosts,
 206                    rnp->n_normal_boosts,
 207                    (int)(jiffies & 0xffff),
 208                    (int)(rnp->boost_time & 0xffff));
 209         seq_printf(m, "%s: nt=%lu egt=%lu bt=%lu nb=%lu ny=%lu nos=%lu\n",
 210                    "     balk",
 211                    rnp->n_balk_blkd_tasks,
 212                    rnp->n_balk_exp_gp_tasks,
 213                    rnp->n_balk_boost_tasks,
 214                    rnp->n_balk_notblocked,
 215                    rnp->n_balk_notyet,
 216                    rnp->n_balk_nos);
 217 }
 218
 219 static int show_rcu_node_boost(struct seq_file *m, void *unused)
 220 {
 221         struct rcu_node *rnp;
 222
 223         rcu_for_each_leaf_node(&rcu_preempt_state, rnp)
 224                 print_one_rcu_node_boost(m, rnp);
 225         return 0;
 226 }
 227
 228 static int rcu_node_boost_open(struct inode *inode, struct file *file)
 229 {
 230         return single_open(file, show_rcu_node_boost, NULL);
 231 }
 232
 233 static const struct file_operations rcu_node_boost_fops = {
 234         .owner = THIS_MODULE,
 235         .open = rcu_node_boost_open,
 236         .read = seq_read,
 237         .llseek = seq_lseek,
 238         .release = single_release,
 239 };
 240
 241 /*
 242  * Create the rcuboost debugfs entry.  Standard error return.
 243  */
 244 static int rcu_boost_trace_create_file(struct dentry *rcudir)
 245 {
 246         return !debugfs_create_file("rcuboost", 0444, rcudir, NULL,
 247                                     &rcu_node_boost_fops);
 248 }
 249
 250 #else /* #ifdef CONFIG_RCU_BOOST */
 251
 252 static int rcu_boost_trace_create_file(struct dentry *rcudir)
 253 {
 254         return 0;  /* There cannot be an error if we didn't create it! */
 255 }
 256
 257 #endif /* #else #ifdef CONFIG_RCU_BOOST */
 258
 259 static void print_one_rcu_state(struct seq_file *m, struct rcu_state *rsp)
 260 {
 261         unsigned long gpnum;
 262         int level = 0;
 263         struct rcu_node *rnp;
 264
 265         gpnum = rsp->gpnum;
 266         seq_printf(m, "c=%lu g=%lu s=%d jfq=%ld j=%x "
 267                       "nfqs=%lu/nfqsng=%lu(%lu) fqlh=%lu\n",
 268                    rsp->completed, gpnum, rsp->signaled,
 269                    (long)(rsp->jiffies_force_qs - jiffies),
 270                    (int)(jiffies & 0xffff),
 271                    rsp->n_force_qs, rsp->n_force_qs_ngp,
 272                    rsp->n_force_qs - rsp->n_force_qs_ngp,
 273                    rsp->n_force_qs_lh);
 274         for (rnp = &rsp->node[0]; rnp - &rsp->node[0] < NUM_RCU_NODES; rnp++) {
 275                 if (rnp->level != level) {
 276                         seq_puts(m, "\n");
 277                         level = rnp->level;
 278                 }
 279                 seq_printf(m, "%lx/%lx %c%c>%c %d:%d ^%d    ",
 280                            rnp->qsmask, rnp->qsmaskinit,
 281                            ".G"[rnp->gp_tasks != NULL],
 282                            ".E"[rnp->exp_tasks != NULL],
 283                            ".T"[!list_empty(&rnp->blkd_tasks)],
 284                            rnp->grplo, rnp->grphi, rnp->grpnum);
 285         }
 286         seq_puts(m, "\n");
 287 }
 288
 289 static int show_rcuhier(struct seq_file *m, void *unused)
 290 {
 291 #ifdef CONFIG_TREE_PREEMPT_RCU
 292         seq_puts(m, "rcu_preempt:\n");
 293         print_one_rcu_state(m, &rcu_preempt_state);
 294 #endif /* #ifdef CONFIG_TREE_PREEMPT_RCU */
 295         seq_puts(m, "rcu_sched:\n");
 296         print_one_rcu_state(m, &rcu_sched_state);
 297         seq_puts(m, "rcu_bh:\n");
 298         print_one_rcu_state(m, &rcu_bh_state);
 299         return 0;
 300 }
 301
 302 static int rcuhier_open(struct inode *inode, struct file *file)
 303 {
 304         return single_open(file, show_rcuhier, NULL);
 305 }
 306
 307 static const struct file_operations rcuhier_fops = {
 308         .owner = THIS_MODULE,
 309         .open = rcuhier_open,
 310         .read = seq_read,
 311         .llseek = seq_lseek,
 312         .release = single_release,
 313 };
 314
 315 static int show_rcugp(struct seq_file *m, void *unused)
 316 {
 317 #ifdef CONFIG_TREE_PREEMPT_RCU
 318         seq_printf(m, "rcu_preempt: completed=%ld  gpnum=%lu\n",
 319                    rcu_preempt_state.completed, rcu_preempt_state.gpnum);
 320 #endif /* #ifdef CONFIG_TREE_PREEMPT_RCU */
 321         seq_printf(m, "rcu_sched: completed=%ld  gpnum=%lu\n",
 322                    rcu_sched_state.completed, rcu_sched_state.gpnum);
 323         seq_printf(m, "rcu_bh: completed=%ld  gpnum=%lu\n",
 324                    rcu_bh_state.completed, rcu_bh_state.gpnum);
 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         seq_printf(m, "%3d%cnp=%ld "
 344                    "qsp=%ld rpq=%ld cbr=%ld cng=%ld "
 345                    "gpc=%ld gps=%ld nf=%ld nn=%ld\n",
 346                    rdp->cpu,
 347                    cpu_is_offline(rdp->cpu) ? '!' : ' ',
 348                    rdp->n_rcu_pending,
 349                    rdp->n_rp_qs_pending,
 350                    rdp->n_rp_report_qs,
 351                    rdp->n_rp_cb_ready,
 352                    rdp->n_rp_cpu_needs_gp,
 353                    rdp->n_rp_gp_completed,
 354                    rdp->n_rp_gp_started,
 355                    rdp->n_rp_need_fqs,
 356                    rdp->n_rp_need_nothing);
 357 }
 358
 359 static void print_rcu_pendings(struct seq_file *m, struct rcu_state *rsp)
 360 {
 361         int cpu;
 362         struct rcu_data *rdp;
 363
 364         for_each_possible_cpu(cpu) {
 365                 rdp = per_cpu_ptr(rsp->rda, cpu);
 366                 if (rdp->beenonline)
 367                         print_one_rcu_pending(m, rdp);
 368         }
 369 }
 370
 371 static int show_rcu_pending(struct seq_file *m, void *unused)
 372 {
 373 #ifdef CONFIG_TREE_PREEMPT_RCU
 374         seq_puts(m, "rcu_preempt:\n");
 375         print_rcu_pendings(m, &rcu_preempt_state);
 376 #endif /* #ifdef CONFIG_TREE_PREEMPT_RCU */
 377         seq_puts(m, "rcu_sched:\n");
 378         print_rcu_pendings(m, &rcu_sched_state);
 379         seq_puts(m, "rcu_bh:\n");
 380         print_rcu_pendings(m, &rcu_bh_state);
 381         return 0;
 382 }
 383
 384 static int rcu_pending_open(struct inode *inode, struct file *file)
 385 {
 386         return single_open(file, show_rcu_pending, NULL);
 387 }
 388
 389 static const struct file_operations rcu_pending_fops = {
 390         .owner = THIS_MODULE,
 391         .open = rcu_pending_open,
 392         .read = seq_read,
 393         .llseek = seq_lseek,
 394         .release = single_release,
 395 };
 396
 397 static struct dentry *rcudir;
 398
 399 static int __init rcutree_trace_init(void)
 400 {
 401         struct dentry *retval;
 402
 403         rcudir = debugfs_create_dir("rcu", NULL);
 404         if (!rcudir)
 405                 goto free_out;
 406
 407         retval = debugfs_create_file("rcudata", 0444, rcudir,
 408                                                 NULL, &rcudata_fops);
 409         if (!retval)
 410                 goto free_out;
 411
 412         retval = debugfs_create_file("rcudata.csv", 0444, rcudir,
 413                                                 NULL, &rcudata_csv_fops);
 414         if (!retval)
 415                 goto free_out;
 416
 417         if (rcu_boost_trace_create_file(rcudir))
 418                 goto free_out;
 419
 420         retval = debugfs_create_file("rcugp", 0444, rcudir, NULL, &rcugp_fops);
 421         if (!retval)
 422                 goto free_out;
 423
 424         retval = debugfs_create_file("rcuhier", 0444, rcudir,
 425                                                 NULL, &rcuhier_fops);
 426         if (!retval)
 427                 goto free_out;
 428
 429         retval = debugfs_create_file("rcu_pending", 0444, rcudir,
 430                                                 NULL, &rcu_pending_fops);
 431         if (!retval)
 432                 goto free_out;
 433         return 0;
 434 free_out:
 435         debugfs_remove_recursive(rcudir);
 436         return 1;
 437 }
 438
 439 static void __exit rcutree_trace_cleanup(void)
 440 {
 441         debugfs_remove_recursive(rcudir);
 442 }
 443
 444
 445 module_init(rcutree_trace_init);
 446 module_exit(rcutree_trace_cleanup);
 447
 448 MODULE_AUTHOR("Paul E. McKenney");
 449 MODULE_DESCRIPTION("Read-Copy Update tracing for hierarchical implementation");
 450 MODULE_LICENSE("GPL");