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