kernel/trace/trace_functions.c

   1 /*
   2  * ring buffer based function tracer
   3  *
   4  * Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com>
   5  * Copyright (C) 2008 Ingo Molnar <mingo@redhat.com>
   6  *
   7  * Based on code from the latency_tracer, that is:
   8  *
   9  *  Copyright (C) 2004-2006 Ingo Molnar
  10  *  Copyright (C) 2004 Nadia Yvette Chambers
  11  */
  12 #include <linux/ring_buffer.h>
  13 #include <linux/debugfs.h>
  14 #include <linux/uaccess.h>
  15 #include <linux/ftrace.h>
  16 #include <linux/slab.h>
  17 #include <linux/fs.h>
  18
  19 #include "trace.h"
  20
  21 static void tracing_start_function_trace(struct trace_array *tr);
  22 static void tracing_stop_function_trace(struct trace_array *tr);
  23 static void
  24 function_trace_call(unsigned long ip, unsigned long parent_ip,
  25                     struct ftrace_ops *op, struct pt_regs *pt_regs);
  26 static void
  27 function_stack_trace_call(unsigned long ip, unsigned long parent_ip,
  28                           struct ftrace_ops *op, struct pt_regs *pt_regs);
  29 static struct tracer_flags func_flags;
  30
  31 /* Our option */
  32 enum {
  33         TRACE_FUNC_OPT_STACK    = 0x1,
  34 };
  35
  36 static int allocate_ftrace_ops(struct trace_array *tr)
  37 {
  38         struct ftrace_ops *ops;
  39
  40         ops = kzalloc(sizeof(*ops), GFP_KERNEL);
  41         if (!ops)
  42                 return -ENOMEM;
  43
  44         /* Currently only the non stack verision is supported */
  45         ops->func = function_trace_call;
  46         ops->flags = FTRACE_OPS_FL_RECURSION_SAFE | FTRACE_OPS_FL_PID;
  47
  48         tr->ops = ops;
  49         ops->private = tr;
  50         return 0;
  51 }
  52
  53
  54 int ftrace_create_function_files(struct trace_array *tr,
  55                                  struct dentry *parent)
  56 {
  57         int ret;
  58
  59         /*
  60          * The top level array uses the "global_ops", and the files are
  61          * created on boot up.
  62          */
  63         if (tr->flags & TRACE_ARRAY_FL_GLOBAL)
  64                 return 0;
  65
  66         ret = allocate_ftrace_ops(tr);
  67         if (ret)
  68                 return ret;
  69
  70         ftrace_create_filter_files(tr->ops, parent);
  71
  72         return 0;
  73 }
  74
  75 void ftrace_destroy_function_files(struct trace_array *tr)
  76 {
  77         ftrace_destroy_filter_files(tr->ops);
  78         kfree(tr->ops);
  79         tr->ops = NULL;
  80 }
  81
  82 static int function_trace_init(struct trace_array *tr)
  83 {
  84         ftrace_func_t func;
  85
  86         /*
  87          * Instance trace_arrays get their ops allocated
  88          * at instance creation. Unless it failed
  89          * the allocation.
  90          */
  91         if (!tr->ops)
  92                 return -ENOMEM;
  93
  94         /* Currently only the global instance can do stack tracing */
  95         if (tr->flags & TRACE_ARRAY_FL_GLOBAL &&
  96             func_flags.val & TRACE_FUNC_OPT_STACK)
  97                 func = function_stack_trace_call;
  98         else
  99                 func = function_trace_call;
 100
 101         ftrace_init_array_ops(tr, func);
 102
 103         tr->trace_buffer.cpu = get_cpu();
 104         put_cpu();
 105
 106         tracing_start_cmdline_record();
 107         tracing_start_function_trace(tr);
 108         return 0;
 109 }
 110
 111 static void function_trace_reset(struct trace_array *tr)
 112 {
 113         tracing_stop_function_trace(tr);
 114         tracing_stop_cmdline_record();
 115         ftrace_reset_array_ops(tr);
 116 }
 117
 118 static void function_trace_start(struct trace_array *tr)
 119 {
 120         tracing_reset_online_cpus(&tr->trace_buffer);
 121 }
 122
 123 static void
 124 function_trace_call(unsigned long ip, unsigned long parent_ip,
 125                     struct ftrace_ops *op, struct pt_regs *pt_regs)
 126 {
 127         struct trace_array *tr = op->private;
 128         struct trace_array_cpu *data;
 129         unsigned long flags;
 130         int bit;
 131         int cpu;
 132         int pc;
 133
 134         if (unlikely(!tr->function_enabled))
 135                 return;
 136
 137         pc = preempt_count();
 138         preempt_disable_notrace();
 139
 140         bit = trace_test_and_set_recursion(TRACE_FTRACE_START, TRACE_FTRACE_MAX);
 141         if (bit < 0)
 142                 goto out;
 143
 144         cpu = smp_processor_id();
 145         data = per_cpu_ptr(tr->trace_buffer.data, cpu);
 146         if (!atomic_read(&data->disabled)) {
 147                 local_save_flags(flags);
 148                 trace_function(tr, ip, parent_ip, flags, pc);
 149         }
 150         trace_clear_recursion(bit);
 151
 152  out:
 153         preempt_enable_notrace();
 154 }
 155
 156 static void
 157 function_stack_trace_call(unsigned long ip, unsigned long parent_ip,
 158                           struct ftrace_ops *op, struct pt_regs *pt_regs)
 159 {
 160         struct trace_array *tr = op->private;
 161         struct trace_array_cpu *data;
 162         unsigned long flags;
 163         long disabled;
 164         int cpu;
 165         int pc;
 166
 167         if (unlikely(!tr->function_enabled))
 168                 return;
 169
 170         /*
 171          * Need to use raw, since this must be called before the
 172          * recursive protection is performed.
 173          */
 174         local_irq_save(flags);
 175         cpu = raw_smp_processor_id();
 176         data = per_cpu_ptr(tr->trace_buffer.data, cpu);
 177         disabled = atomic_inc_return(&data->disabled);
 178
 179         if (likely(disabled == 1)) {
 180                 pc = preempt_count();
 181                 trace_function(tr, ip, parent_ip, flags, pc);
 182                 /*
 183                  * skip over 5 funcs:
 184                  *    __ftrace_trace_stack,
 185                  *    __trace_stack,
 186                  *    function_stack_trace_call
 187                  *    ftrace_list_func
 188                  *    ftrace_call
 189                  */
 190                 __trace_stack(tr, flags, 5, pc);
 191         }
 192
 193         atomic_dec(&data->disabled);
 194         local_irq_restore(flags);
 195 }
 196
 197 static struct tracer_opt func_opts[] = {
 198 #ifdef CONFIG_STACKTRACE
 199         { TRACER_OPT(func_stack_trace, TRACE_FUNC_OPT_STACK) },
 200 #endif
 201         { } /* Always set a last empty entry */
 202 };
 203
 204 static struct tracer_flags func_flags = {
 205         .val = 0, /* By default: all flags disabled */
 206         .opts = func_opts
 207 };
 208
 209 static void tracing_start_function_trace(struct trace_array *tr)
 210 {
 211         tr->function_enabled = 0;
 212         register_ftrace_function(tr->ops);
 213         tr->function_enabled = 1;
 214 }
 215
 216 static void tracing_stop_function_trace(struct trace_array *tr)
 217 {
 218         tr->function_enabled = 0;
 219         unregister_ftrace_function(tr->ops);
 220 }
 221
 222 static struct tracer function_trace;
 223
 224 static int
 225 func_set_flag(struct trace_array *tr, u32 old_flags, u32 bit, int set)
 226 {
 227         switch (bit) {
 228         case TRACE_FUNC_OPT_STACK:
 229                 /* do nothing if already set */
 230                 if (!!set == !!(func_flags.val & TRACE_FUNC_OPT_STACK))
 231                         break;
 232
 233                 /* We can change this flag when not running. */
 234                 if (tr->current_trace != &function_trace)
 235                         break;
 236
 237                 unregister_ftrace_function(tr->ops);
 238
 239                 if (set) {
 240                         tr->ops->func = function_stack_trace_call;
 241                         register_ftrace_function(tr->ops);
 242                 } else {
 243                         tr->ops->func = function_trace_call;
 244                         register_ftrace_function(tr->ops);
 245                 }
 246
 247                 break;
 248         default:
 249                 return -EINVAL;
 250         }
 251
 252         return 0;
 253 }
 254
 255 static struct tracer function_trace __tracer_data =
 256 {
 257         .name           = "function",
 258         .init           = function_trace_init,
 259         .reset          = function_trace_reset,
 260         .start          = function_trace_start,
 261         .flags          = &func_flags,
 262         .set_flag       = func_set_flag,
 263         .allow_instances = true,
 264 #ifdef CONFIG_FTRACE_SELFTEST
 265         .selftest       = trace_selftest_startup_function,
 266 #endif
 267 };
 268
 269 #ifdef CONFIG_DYNAMIC_FTRACE
 270 static void update_traceon_count(struct ftrace_probe_ops *ops,
 271                                  unsigned long ip,
 272                                  struct trace_array *tr, bool on,
 273                                  void *data)
 274 {
 275         struct ftrace_func_mapper *mapper = data;
 276         long *count;
 277         long old_count;
 278
 279         /*
 280          * Tracing gets disabled (or enabled) once per count.
 281          * This function can be called at the same time on multiple CPUs.
 282          * It is fine if both disable (or enable) tracing, as disabling
 283          * (or enabling) the second time doesn't do anything as the
 284          * state of the tracer is already disabled (or enabled).
 285          * What needs to be synchronized in this case is that the count
 286          * only gets decremented once, even if the tracer is disabled
 287          * (or enabled) twice, as the second one is really a nop.
 288          *
 289          * The memory barriers guarantee that we only decrement the
 290          * counter once. First the count is read to a local variable
 291          * and a read barrier is used to make sure that it is loaded
 292          * before checking if the tracer is in the state we want.
 293          * If the tracer is not in the state we want, then the count
 294          * is guaranteed to be the old count.
 295          *
 296          * Next the tracer is set to the state we want (disabled or enabled)
 297          * then a write memory barrier is used to make sure that
 298          * the new state is visible before changing the counter by
 299          * one minus the old counter. This guarantees that another CPU
 300          * executing this code will see the new state before seeing
 301          * the new counter value, and would not do anything if the new
 302          * counter is seen.
 303          *
 304          * Note, there is no synchronization between this and a user
 305          * setting the tracing_on file. But we currently don't care
 306          * about that.
 307          */
 308         count = (long *)ftrace_func_mapper_find_ip(mapper, ip);
 309         old_count = *count;
 310
 311         if (old_count <= 0)
 312                 return;
 313
 314         /* Make sure we see count before checking tracing state */
 315         smp_rmb();
 316
 317         if (on == !!tracer_tracing_is_on(tr))
 318                 return;
 319
 320         if (on)
 321                 tracer_tracing_on(tr);
 322         else
 323                 tracer_tracing_off(tr);
 324
 325         /* Make sure tracing state is visible before updating count */
 326         smp_wmb();
 327
 328         *count = old_count - 1;
 329 }
 330
 331 static void
 332 ftrace_traceon_count(unsigned long ip, unsigned long parent_ip,
 333                      struct trace_array *tr, struct ftrace_probe_ops *ops,
 334                      void *data)
 335 {
 336         update_traceon_count(ops, ip, tr, 1, data);
 337 }
 338
 339 static void
 340 ftrace_traceoff_count(unsigned long ip, unsigned long parent_ip,
 341                       struct trace_array *tr, struct ftrace_probe_ops *ops,
 342                       void *data)
 343 {
 344         update_traceon_count(ops, ip, tr, 0, data);
 345 }
 346
 347 static void
 348 ftrace_traceon(unsigned long ip, unsigned long parent_ip,
 349                struct trace_array *tr, struct ftrace_probe_ops *ops,
 350                void *data)
 351 {
 352         if (tracer_tracing_is_on(tr))
 353                 return;
 354
 355         tracer_tracing_on(tr);
 356 }
 357
 358 static void
 359 ftrace_traceoff(unsigned long ip, unsigned long parent_ip,
 360                 struct trace_array *tr, struct ftrace_probe_ops *ops,
 361                 void *data)
 362 {
 363         if (!tracer_tracing_is_on(tr))
 364                 return;
 365
 366         tracer_tracing_off(tr);
 367 }
 368
 369 /*
 370  * Skip 4:
 371  *   ftrace_stacktrace()
 372  *   function_trace_probe_call()
 373  *   ftrace_ops_list_func()
 374  *   ftrace_call()
 375  */
 376 #define STACK_SKIP 4
 377
 378 static __always_inline void trace_stack(struct trace_array *tr)
 379 {
 380         unsigned long flags;
 381         int pc;
 382
 383         local_save_flags(flags);
 384         pc = preempt_count();
 385
 386         __trace_stack(tr, flags, STACK_SKIP, pc);
 387 }
 388
 389 static void
 390 ftrace_stacktrace(unsigned long ip, unsigned long parent_ip,
 391                   struct trace_array *tr, struct ftrace_probe_ops *ops,
 392                   void *data)
 393 {
 394         trace_stack(tr);
 395 }
 396
 397 static void
 398 ftrace_stacktrace_count(unsigned long ip, unsigned long parent_ip,
 399                         struct trace_array *tr, struct ftrace_probe_ops *ops,
 400                         void *data)
 401 {
 402         struct ftrace_func_mapper *mapper = data;
 403         long *count;
 404         long old_count;
 405         long new_count;
 406
 407         if (!tracing_is_on())
 408                 return;
 409
 410         /* unlimited? */
 411         if (!mapper) {
 412                 trace_stack(tr);
 413                 return;
 414         }
 415
 416         count = (long *)ftrace_func_mapper_find_ip(mapper, ip);
 417
 418         /*
 419          * Stack traces should only execute the number of times the
 420          * user specified in the counter.
 421          */
 422         do {
 423                 old_count = *count;
 424
 425                 if (!old_count)
 426                         return;
 427
 428                 new_count = old_count - 1;
 429                 new_count = cmpxchg(count, old_count, new_count);
 430                 if (new_count == old_count)
 431                         trace_stack(tr);
 432
 433                 if (!tracing_is_on())
 434                         return;
 435
 436         } while (new_count != old_count);
 437 }
 438
 439 static int update_count(struct ftrace_probe_ops *ops, unsigned long ip,
 440                         void *data)
 441 {
 442         struct ftrace_func_mapper *mapper = data;
 443         long *count = NULL;
 444
 445         if (mapper)
 446                 count = (long *)ftrace_func_mapper_find_ip(mapper, ip);
 447
 448         if (count) {
 449                 if (*count <= 0)
 450                         return 0;
 451                 (*count)--;
 452         }
 453
 454         return 1;
 455 }
 456
 457 static void
 458 ftrace_dump_probe(unsigned long ip, unsigned long parent_ip,
 459                   struct trace_array *tr, struct ftrace_probe_ops *ops,
 460                   void *data)
 461 {
 462         if (update_count(ops, ip, data))
 463                 ftrace_dump(DUMP_ALL);
 464 }
 465
 466 /* Only dump the current CPU buffer. */
 467 static void
 468 ftrace_cpudump_probe(unsigned long ip, unsigned long parent_ip,
 469                      struct trace_array *tr, struct ftrace_probe_ops *ops,
 470                      void *data)
 471 {
 472         if (update_count(ops, ip, data))
 473                 ftrace_dump(DUMP_ORIG);
 474 }
 475
 476 static int
 477 ftrace_probe_print(const char *name, struct seq_file *m,
 478                    unsigned long ip, struct ftrace_probe_ops *ops,
 479                    void *data)
 480 {
 481         struct ftrace_func_mapper *mapper = data;
 482         long *count = NULL;
 483
 484         seq_printf(m, "%ps:%s", (void *)ip, name);
 485
 486         if (mapper)
 487                 count = (long *)ftrace_func_mapper_find_ip(mapper, ip);
 488
 489         if (count)
 490                 seq_printf(m, ":count=%ld\n", *count);
 491         else
 492                 seq_puts(m, ":unlimited\n");
 493
 494         return 0;
 495 }
 496
 497 static int
 498 ftrace_traceon_print(struct seq_file *m, unsigned long ip,
 499                      struct ftrace_probe_ops *ops,
 500                      void *data)
 501 {
 502         return ftrace_probe_print("traceon", m, ip, ops, data);
 503 }
 504
 505 static int
 506 ftrace_traceoff_print(struct seq_file *m, unsigned long ip,
 507                          struct ftrace_probe_ops *ops, void *data)
 508 {
 509         return ftrace_probe_print("traceoff", m, ip, ops, data);
 510 }
 511
 512 static int
 513 ftrace_stacktrace_print(struct seq_file *m, unsigned long ip,
 514                         struct ftrace_probe_ops *ops, void *data)
 515 {
 516         return ftrace_probe_print("stacktrace", m, ip, ops, data);
 517 }
 518
 519 static int
 520 ftrace_dump_print(struct seq_file *m, unsigned long ip,
 521                         struct ftrace_probe_ops *ops, void *data)
 522 {
 523         return ftrace_probe_print("dump", m, ip, ops, data);
 524 }
 525
 526 static int
 527 ftrace_cpudump_print(struct seq_file *m, unsigned long ip,
 528                         struct ftrace_probe_ops *ops, void *data)
 529 {
 530         return ftrace_probe_print("cpudump", m, ip, ops, data);
 531 }
 532
 533
 534 static int
 535 ftrace_count_init(struct ftrace_probe_ops *ops, struct trace_array *tr,
 536                   unsigned long ip, void *init_data, void **data)
 537 {
 538         struct ftrace_func_mapper *mapper = *data;
 539
 540         if (!mapper) {
 541                 mapper = allocate_ftrace_func_mapper();
 542                 if (!mapper)
 543                         return -ENOMEM;
 544                 *data = mapper;
 545         }
 546
 547         return ftrace_func_mapper_add_ip(mapper, ip, init_data);
 548 }
 549
 550 static void
 551 ftrace_count_free(struct ftrace_probe_ops *ops, struct trace_array *tr,
 552                   unsigned long ip, void *data)
 553 {
 554         struct ftrace_func_mapper *mapper = data;
 555
 556         if (!ip) {
 557                 free_ftrace_func_mapper(mapper, NULL);
 558                 return;
 559         }
 560
 561         ftrace_func_mapper_remove_ip(mapper, ip);
 562 }
 563
 564 static struct ftrace_probe_ops traceon_count_probe_ops = {
 565         .func                   = ftrace_traceon_count,
 566         .print                  = ftrace_traceon_print,
 567         .init                   = ftrace_count_init,
 568         .free                   = ftrace_count_free,
 569 };
 570
 571 static struct ftrace_probe_ops traceoff_count_probe_ops = {
 572         .func                   = ftrace_traceoff_count,
 573         .print                  = ftrace_traceoff_print,
 574         .init                   = ftrace_count_init,
 575         .free                   = ftrace_count_free,
 576 };
 577
 578 static struct ftrace_probe_ops stacktrace_count_probe_ops = {
 579         .func                   = ftrace_stacktrace_count,
 580         .print                  = ftrace_stacktrace_print,
 581         .init                   = ftrace_count_init,
 582         .free                   = ftrace_count_free,
 583 };
 584
 585 static struct ftrace_probe_ops dump_probe_ops = {
 586         .func                   = ftrace_dump_probe,
 587         .print                  = ftrace_dump_print,
 588         .init                   = ftrace_count_init,
 589         .free                   = ftrace_count_free,
 590 };
 591
 592 static struct ftrace_probe_ops cpudump_probe_ops = {
 593         .func                   = ftrace_cpudump_probe,
 594         .print                  = ftrace_cpudump_print,
 595 };
 596
 597 static struct ftrace_probe_ops traceon_probe_ops = {
 598         .func                   = ftrace_traceon,
 599         .print                  = ftrace_traceon_print,
 600 };
 601
 602 static struct ftrace_probe_ops traceoff_probe_ops = {
 603         .func                   = ftrace_traceoff,
 604         .print                  = ftrace_traceoff_print,
 605 };
 606
 607 static struct ftrace_probe_ops stacktrace_probe_ops = {
 608         .func                   = ftrace_stacktrace,
 609         .print                  = ftrace_stacktrace_print,
 610 };
 611
 612 static int
 613 ftrace_trace_probe_callback(struct trace_array *tr,
 614                             struct ftrace_probe_ops *ops,
 615                             struct ftrace_hash *hash, char *glob,
 616                             char *cmd, char *param, int enable)
 617 {
 618         void *count = (void *)-1;
 619         char *number;
 620         int ret;
 621
 622         /* hash funcs only work with set_ftrace_filter */
 623         if (!enable)
 624                 return -EINVAL;
 625
 626         if (glob[0] == '!')
 627                 return unregister_ftrace_function_probe_func(glob+1, tr, ops);
 628
 629         if (!param)
 630                 goto out_reg;
 631
 632         number = strsep(&param, ":");
 633
 634         if (!strlen(number))
 635                 goto out_reg;
 636
 637         /*
 638          * We use the callback data field (which is a pointer)
 639          * as our counter.
 640          */
 641         ret = kstrtoul(number, 0, (unsigned long *)&count);
 642         if (ret)
 643                 return ret;
 644
 645  out_reg:
 646         ret = register_ftrace_function_probe(glob, tr, ops, count);
 647
 648         return ret < 0 ? ret : 0;
 649 }
 650
 651 static int
 652 ftrace_trace_onoff_callback(struct trace_array *tr, struct ftrace_hash *hash,
 653                             char *glob, char *cmd, char *param, int enable)
 654 {
 655         struct ftrace_probe_ops *ops;
 656
 657         if (!tr)
 658                 return -ENODEV;
 659
 660         /* we register both traceon and traceoff to this callback */
 661         if (strcmp(cmd, "traceon") == 0)
 662                 ops = param ? &traceon_count_probe_ops : &traceon_probe_ops;
 663         else
 664                 ops = param ? &traceoff_count_probe_ops : &traceoff_probe_ops;
 665
 666         return ftrace_trace_probe_callback(tr, ops, hash, glob, cmd,
 667                                            param, enable);
 668 }
 669
 670 static int
 671 ftrace_stacktrace_callback(struct trace_array *tr, struct ftrace_hash *hash,
 672                            char *glob, char *cmd, char *param, int enable)
 673 {
 674         struct ftrace_probe_ops *ops;
 675
 676         if (!tr)
 677                 return -ENODEV;
 678
 679         ops = param ? &stacktrace_count_probe_ops : &stacktrace_probe_ops;
 680
 681         return ftrace_trace_probe_callback(tr, ops, hash, glob, cmd,
 682                                            param, enable);
 683 }
 684
 685 static int
 686 ftrace_dump_callback(struct trace_array *tr, struct ftrace_hash *hash,
 687                            char *glob, char *cmd, char *param, int enable)
 688 {
 689         struct ftrace_probe_ops *ops;
 690
 691         if (!tr)
 692                 return -ENODEV;
 693
 694         ops = &dump_probe_ops;
 695
 696         /* Only dump once. */
 697         return ftrace_trace_probe_callback(tr, ops, hash, glob, cmd,
 698                                            "1", enable);
 699 }
 700
 701 static int
 702 ftrace_cpudump_callback(struct trace_array *tr, struct ftrace_hash *hash,
 703                            char *glob, char *cmd, char *param, int enable)
 704 {
 705         struct ftrace_probe_ops *ops;
 706
 707         if (!tr)
 708                 return -ENODEV;
 709
 710         ops = &cpudump_probe_ops;
 711
 712         /* Only dump once. */
 713         return ftrace_trace_probe_callback(tr, ops, hash, glob, cmd,
 714                                            "1", enable);
 715 }
 716
 717 static struct ftrace_func_command ftrace_traceon_cmd = {
 718         .name                   = "traceon",
 719         .func                   = ftrace_trace_onoff_callback,
 720 };
 721
 722 static struct ftrace_func_command ftrace_traceoff_cmd = {
 723         .name                   = "traceoff",
 724         .func                   = ftrace_trace_onoff_callback,
 725 };
 726
 727 static struct ftrace_func_command ftrace_stacktrace_cmd = {
 728         .name                   = "stacktrace",
 729         .func                   = ftrace_stacktrace_callback,
 730 };
 731
 732 static struct ftrace_func_command ftrace_dump_cmd = {
 733         .name                   = "dump",
 734         .func                   = ftrace_dump_callback,
 735 };
 736
 737 static struct ftrace_func_command ftrace_cpudump_cmd = {
 738         .name                   = "cpudump",
 739         .func                   = ftrace_cpudump_callback,
 740 };
 741
 742 static int __init init_func_cmd_traceon(void)
 743 {
 744         int ret;
 745
 746         ret = register_ftrace_command(&ftrace_traceoff_cmd);
 747         if (ret)
 748                 return ret;
 749
 750         ret = register_ftrace_command(&ftrace_traceon_cmd);
 751         if (ret)
 752                 goto out_free_traceoff;
 753
 754         ret = register_ftrace_command(&ftrace_stacktrace_cmd);
 755         if (ret)
 756                 goto out_free_traceon;
 757
 758         ret = register_ftrace_command(&ftrace_dump_cmd);
 759         if (ret)
 760                 goto out_free_stacktrace;
 761
 762         ret = register_ftrace_command(&ftrace_cpudump_cmd);
 763         if (ret)
 764                 goto out_free_dump;
 765
 766         return 0;
 767
 768  out_free_dump:
 769         unregister_ftrace_command(&ftrace_dump_cmd);
 770  out_free_stacktrace:
 771         unregister_ftrace_command(&ftrace_stacktrace_cmd);
 772  out_free_traceon:
 773         unregister_ftrace_command(&ftrace_traceon_cmd);
 774  out_free_traceoff:
 775         unregister_ftrace_command(&ftrace_traceoff_cmd);
 776
 777         return ret;
 778 }
 779 #else
 780 static inline int init_func_cmd_traceon(void)
 781 {
 782         return 0;
 783 }
 784 #endif /* CONFIG_DYNAMIC_FTRACE */
 785
 786 __init int init_function_trace(void)
 787 {
 788         init_func_cmd_traceon();
 789         return register_tracer(&function_trace);
 790 }