kernel/trace/trace_irqsoff.c

   1 /*
   2  * trace irqs off critical timings
   3  *
   4  * Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com>
   5  * Copyright (C) 2008 Ingo Molnar <mingo@redhat.com>
   6  *
   7  * From code in the latency_tracer, that is:
   8  *
   9  *  Copyright (C) 2004-2006 Ingo Molnar
  10  *  Copyright (C) 2004 Nadia Yvette Chambers
  11  */
  12 #include <linux/kallsyms.h>
  13 #include <linux/debugfs.h>
  14 #include <linux/uaccess.h>
  15 #include <linux/module.h>
  16 #include <linux/ftrace.h>
  17 #include <linux/fs.h>
  18
  19 #include "trace.h"
  20
  21 static struct trace_array               *irqsoff_trace __read_mostly;
  22 static int                              tracer_enabled __read_mostly;
  23
  24 static DEFINE_PER_CPU(int, tracing_cpu);
  25
  26 static DEFINE_RAW_SPINLOCK(max_trace_lock);
  27
  28 enum {
  29         TRACER_IRQS_OFF         = (1 << 1),
  30         TRACER_PREEMPT_OFF      = (1 << 2),
  31 };
  32
  33 static int trace_type __read_mostly;
  34
  35 static int save_flags;
  36 static bool function_enabled;
  37
  38 static void stop_irqsoff_tracer(struct trace_array *tr, int graph);
  39 static int start_irqsoff_tracer(struct trace_array *tr, int graph);
  40
  41 #ifdef CONFIG_PREEMPT_TRACER
  42 static inline int
  43 preempt_trace(void)
  44 {
  45         return ((trace_type & TRACER_PREEMPT_OFF) && preempt_count());
  46 }
  47 #else
  48 # define preempt_trace() (0)
  49 #endif
  50
  51 #ifdef CONFIG_IRQSOFF_TRACER
  52 static inline int
  53 irq_trace(void)
  54 {
  55         return ((trace_type & TRACER_IRQS_OFF) &&
  56                 irqs_disabled());
  57 }
  58 #else
  59 # define irq_trace() (0)
  60 #endif
  61
  62 #define TRACE_DISPLAY_GRAPH     1
  63
  64 static struct tracer_opt trace_opts[] = {
  65 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
  66         /* display latency trace as call graph */
  67         { TRACER_OPT(display-graph, TRACE_DISPLAY_GRAPH) },
  68 #endif
  69         { } /* Empty entry */
  70 };
  71
  72 static struct tracer_flags tracer_flags = {
  73         .val  = 0,
  74         .opts = trace_opts,
  75 };
  76
  77 #define is_graph() (tracer_flags.val & TRACE_DISPLAY_GRAPH)
  78
  79 /*
  80  * Sequence count - we record it when starting a measurement and
  81  * skip the latency if the sequence has changed - some other section
  82  * did a maximum and could disturb our measurement with serial console
  83  * printouts, etc. Truly coinciding maximum latencies should be rare
  84  * and what happens together happens separately as well, so this doesn't
  85  * decrease the validity of the maximum found:
  86  */
  87 static __cacheline_aligned_in_smp       unsigned long max_sequence;
  88
  89 #ifdef CONFIG_FUNCTION_TRACER
  90 /*
  91  * Prologue for the preempt and irqs off function tracers.
  92  *
  93  * Returns 1 if it is OK to continue, and data->disabled is
  94  *            incremented.
  95  *         0 if the trace is to be ignored, and data->disabled
  96  *            is kept the same.
  97  *
  98  * Note, this function is also used outside this ifdef but
  99  *  inside the #ifdef of the function graph tracer below.
 100  *  This is OK, since the function graph tracer is
 101  *  dependent on the function tracer.
 102  */
 103 static int func_prolog_dec(struct trace_array *tr,
 104                            struct trace_array_cpu **data,
 105                            unsigned long *flags)
 106 {
 107         long disabled;
 108         int cpu;
 109
 110         /*
 111          * Does not matter if we preempt. We test the flags
 112          * afterward, to see if irqs are disabled or not.
 113          * If we preempt and get a false positive, the flags
 114          * test will fail.
 115          */
 116         cpu = raw_smp_processor_id();
 117         if (likely(!per_cpu(tracing_cpu, cpu)))
 118                 return 0;
 119
 120         local_save_flags(*flags);
 121         /* slight chance to get a false positive on tracing_cpu */
 122         if (!irqs_disabled_flags(*flags))
 123                 return 0;
 124
 125         *data = per_cpu_ptr(tr->trace_buffer.data, cpu);
 126         disabled = atomic_inc_return(&(*data)->disabled);
 127
 128         if (likely(disabled == 1))
 129                 return 1;
 130
 131         atomic_dec(&(*data)->disabled);
 132
 133         return 0;
 134 }
 135
 136 /*
 137  * irqsoff uses its own tracer function to keep the overhead down:
 138  */
 139 static void
 140 irqsoff_tracer_call(unsigned long ip, unsigned long parent_ip,
 141                     struct ftrace_ops *op, struct pt_regs *pt_regs)
 142 {
 143         struct trace_array *tr = irqsoff_trace;
 144         struct trace_array_cpu *data;
 145         unsigned long flags;
 146
 147         if (!func_prolog_dec(tr, &data, &flags))
 148                 return;
 149
 150         trace_function(tr, ip, parent_ip, flags, preempt_count());
 151
 152         atomic_dec(&data->disabled);
 153 }
 154
 155 static struct ftrace_ops trace_ops __read_mostly =
 156 {
 157         .func = irqsoff_tracer_call,
 158         .flags = FTRACE_OPS_FL_GLOBAL | FTRACE_OPS_FL_RECURSION_SAFE,
 159 };
 160 #endif /* CONFIG_FUNCTION_TRACER */
 161
 162 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
 163 static int irqsoff_set_flag(u32 old_flags, u32 bit, int set)
 164 {
 165         int cpu;
 166
 167         if (!(bit & TRACE_DISPLAY_GRAPH))
 168                 return -EINVAL;
 169
 170         if (!(is_graph() ^ set))
 171                 return 0;
 172
 173         stop_irqsoff_tracer(irqsoff_trace, !set);
 174
 175         for_each_possible_cpu(cpu)
 176                 per_cpu(tracing_cpu, cpu) = 0;
 177
 178         tracing_max_latency = 0;
 179         tracing_reset_online_cpus(&irqsoff_trace->trace_buffer);
 180
 181         return start_irqsoff_tracer(irqsoff_trace, set);
 182 }
 183
 184 static int irqsoff_graph_entry(struct ftrace_graph_ent *trace)
 185 {
 186         struct trace_array *tr = irqsoff_trace;
 187         struct trace_array_cpu *data;
 188         unsigned long flags;
 189         int ret;
 190         int pc;
 191
 192         if (!func_prolog_dec(tr, &data, &flags))
 193                 return 0;
 194
 195         pc = preempt_count();
 196         ret = __trace_graph_entry(tr, trace, flags, pc);
 197         atomic_dec(&data->disabled);
 198
 199         return ret;
 200 }
 201
 202 static void irqsoff_graph_return(struct ftrace_graph_ret *trace)
 203 {
 204         struct trace_array *tr = irqsoff_trace;
 205         struct trace_array_cpu *data;
 206         unsigned long flags;
 207         int pc;
 208
 209         if (!func_prolog_dec(tr, &data, &flags))
 210                 return;
 211
 212         pc = preempt_count();
 213         __trace_graph_return(tr, trace, flags, pc);
 214         atomic_dec(&data->disabled);
 215 }
 216
 217 static void irqsoff_trace_open(struct trace_iterator *iter)
 218 {
 219         if (is_graph())
 220                 graph_trace_open(iter);
 221
 222 }
 223
 224 static void irqsoff_trace_close(struct trace_iterator *iter)
 225 {
 226         if (iter->private)
 227                 graph_trace_close(iter);
 228 }
 229
 230 #define GRAPH_TRACER_FLAGS (TRACE_GRAPH_PRINT_CPU | \
 231                             TRACE_GRAPH_PRINT_PROC | \
 232                             TRACE_GRAPH_PRINT_ABS_TIME | \
 233                             TRACE_GRAPH_PRINT_DURATION)
 234
 235 static enum print_line_t irqsoff_print_line(struct trace_iterator *iter)
 236 {
 237         /*
 238          * In graph mode call the graph tracer output function,
 239          * otherwise go with the TRACE_FN event handler
 240          */
 241         if (is_graph())
 242                 return print_graph_function_flags(iter, GRAPH_TRACER_FLAGS);
 243
 244         return TRACE_TYPE_UNHANDLED;
 245 }
 246
 247 static void irqsoff_print_header(struct seq_file *s)
 248 {
 249         if (is_graph())
 250                 print_graph_headers_flags(s, GRAPH_TRACER_FLAGS);
 251         else
 252                 trace_default_header(s);
 253 }
 254
 255 static void
 256 __trace_function(struct trace_array *tr,
 257                  unsigned long ip, unsigned long parent_ip,
 258                  unsigned long flags, int pc)
 259 {
 260         if (is_graph())
 261                 trace_graph_function(tr, ip, parent_ip, flags, pc);
 262         else
 263                 trace_function(tr, ip, parent_ip, flags, pc);
 264 }
 265
 266 #else
 267 #define __trace_function trace_function
 268
 269 static int irqsoff_set_flag(u32 old_flags, u32 bit, int set)
 270 {
 271         return -EINVAL;
 272 }
 273
 274 static int irqsoff_graph_entry(struct ftrace_graph_ent *trace)
 275 {
 276         return -1;
 277 }
 278
 279 static enum print_line_t irqsoff_print_line(struct trace_iterator *iter)
 280 {
 281         return TRACE_TYPE_UNHANDLED;
 282 }
 283
 284 static void irqsoff_graph_return(struct ftrace_graph_ret *trace) { }
 285 static void irqsoff_trace_open(struct trace_iterator *iter) { }
 286 static void irqsoff_trace_close(struct trace_iterator *iter) { }
 287
 288 #ifdef CONFIG_FUNCTION_TRACER
 289 static void irqsoff_print_header(struct seq_file *s)
 290 {
 291         trace_default_header(s);
 292 }
 293 #else
 294 static void irqsoff_print_header(struct seq_file *s)
 295 {
 296         trace_latency_header(s);
 297 }
 298 #endif /* CONFIG_FUNCTION_TRACER */
 299 #endif /* CONFIG_FUNCTION_GRAPH_TRACER */
 300
 301 /*
 302  * Should this new latency be reported/recorded?
 303  */
 304 static int report_latency(cycle_t delta)
 305 {
 306         if (tracing_thresh) {
 307                 if (delta < tracing_thresh)
 308                         return 0;
 309         } else {
 310                 if (delta <= tracing_max_latency)
 311                         return 0;
 312         }
 313         return 1;
 314 }
 315
 316 static void
 317 check_critical_timing(struct trace_array *tr,
 318                       struct trace_array_cpu *data,
 319                       unsigned long parent_ip,
 320                       int cpu)
 321 {
 322         cycle_t T0, T1, delta;
 323         unsigned long flags;
 324         int pc;
 325
 326         T0 = data->preempt_timestamp;
 327         T1 = ftrace_now(cpu);
 328         delta = T1-T0;
 329
 330         local_save_flags(flags);
 331
 332         pc = preempt_count();
 333
 334         if (!report_latency(delta))
 335                 goto out;
 336
 337         raw_spin_lock_irqsave(&max_trace_lock, flags);
 338
 339         /* check if we are still the max latency */
 340         if (!report_latency(delta))
 341                 goto out_unlock;
 342
 343         __trace_function(tr, CALLER_ADDR0, parent_ip, flags, pc);
 344         /* Skip 5 functions to get to the irq/preempt enable function */
 345         __trace_stack(tr, flags, 5, pc);
 346
 347         if (data->critical_sequence != max_sequence)
 348                 goto out_unlock;
 349
 350         data->critical_end = parent_ip;
 351
 352         if (likely(!is_tracing_stopped())) {
 353                 tracing_max_latency = delta;
 354                 update_max_tr_single(tr, current, cpu);
 355         }
 356
 357         max_sequence++;
 358
 359 out_unlock:
 360         raw_spin_unlock_irqrestore(&max_trace_lock, flags);
 361
 362 out:
 363         data->critical_sequence = max_sequence;
 364         data->preempt_timestamp = ftrace_now(cpu);
 365         __trace_function(tr, CALLER_ADDR0, parent_ip, flags, pc);
 366 }
 367
 368 static inline void
 369 start_critical_timing(unsigned long ip, unsigned long parent_ip)
 370 {
 371         int cpu;
 372         struct trace_array *tr = irqsoff_trace;
 373         struct trace_array_cpu *data;
 374         unsigned long flags;
 375
 376         if (likely(!tracer_enabled))
 377                 return;
 378
 379         cpu = raw_smp_processor_id();
 380
 381         if (per_cpu(tracing_cpu, cpu))
 382                 return;
 383
 384         data = per_cpu_ptr(tr->trace_buffer.data, cpu);
 385
 386         if (unlikely(!data) || atomic_read(&data->disabled))
 387                 return;
 388
 389         atomic_inc(&data->disabled);
 390
 391         data->critical_sequence = max_sequence;
 392         data->preempt_timestamp = ftrace_now(cpu);
 393         data->critical_start = parent_ip ? : ip;
 394
 395         local_save_flags(flags);
 396
 397         __trace_function(tr, ip, parent_ip, flags, preempt_count());
 398
 399         per_cpu(tracing_cpu, cpu) = 1;
 400
 401         atomic_dec(&data->disabled);
 402 }
 403
 404 static inline void
 405 stop_critical_timing(unsigned long ip, unsigned long parent_ip)
 406 {
 407         int cpu;
 408         struct trace_array *tr = irqsoff_trace;
 409         struct trace_array_cpu *data;
 410         unsigned long flags;
 411
 412         cpu = raw_smp_processor_id();
 413         /* Always clear the tracing cpu on stopping the trace */
 414         if (unlikely(per_cpu(tracing_cpu, cpu)))
 415                 per_cpu(tracing_cpu, cpu) = 0;
 416         else
 417                 return;
 418
 419         if (!tracer_enabled)
 420                 return;
 421
 422         data = per_cpu_ptr(tr->trace_buffer.data, cpu);
 423
 424         if (unlikely(!data) ||
 425             !data->critical_start || atomic_read(&data->disabled))
 426                 return;
 427
 428         atomic_inc(&data->disabled);
 429
 430         local_save_flags(flags);
 431         __trace_function(tr, ip, parent_ip, flags, preempt_count());
 432         check_critical_timing(tr, data, parent_ip ? : ip, cpu);
 433         data->critical_start = 0;
 434         atomic_dec(&data->disabled);
 435 }
 436
 437 /* start and stop critical timings used to for stoppage (in idle) */
 438 void start_critical_timings(void)
 439 {
 440         if (preempt_trace() || irq_trace())
 441                 start_critical_timing(CALLER_ADDR0, CALLER_ADDR1);
 442 }
 443 EXPORT_SYMBOL_GPL(start_critical_timings);
 444
 445 void stop_critical_timings(void)
 446 {
 447         if (preempt_trace() || irq_trace())
 448                 stop_critical_timing(CALLER_ADDR0, CALLER_ADDR1);
 449 }
 450 EXPORT_SYMBOL_GPL(stop_critical_timings);
 451
 452 #ifdef CONFIG_IRQSOFF_TRACER
 453 #ifdef CONFIG_PROVE_LOCKING
 454 void time_hardirqs_on(unsigned long a0, unsigned long a1)
 455 {
 456         if (!preempt_trace() && irq_trace())
 457                 stop_critical_timing(a0, a1);
 458 }
 459
 460 void time_hardirqs_off(unsigned long a0, unsigned long a1)
 461 {
 462         if (!preempt_trace() && irq_trace())
 463                 start_critical_timing(a0, a1);
 464 }
 465
 466 #else /* !CONFIG_PROVE_LOCKING */
 467
 468 /*
 469  * Stubs:
 470  */
 471
 472 void trace_softirqs_on(unsigned long ip)
 473 {
 474 }
 475
 476 void trace_softirqs_off(unsigned long ip)
 477 {
 478 }
 479
 480 inline void print_irqtrace_events(struct task_struct *curr)
 481 {
 482 }
 483
 484 /*
 485  * We are only interested in hardirq on/off events:
 486  */
 487 void trace_hardirqs_on(void)
 488 {
 489         if (!preempt_trace() && irq_trace())
 490                 stop_critical_timing(CALLER_ADDR0, CALLER_ADDR1);
 491 }
 492 EXPORT_SYMBOL(trace_hardirqs_on);
 493
 494 void trace_hardirqs_off(void)
 495 {
 496         if (!preempt_trace() && irq_trace())
 497                 start_critical_timing(CALLER_ADDR0, CALLER_ADDR1);
 498 }
 499 EXPORT_SYMBOL(trace_hardirqs_off);
 500
 501 void trace_hardirqs_on_caller(unsigned long caller_addr)
 502 {
 503         if (!preempt_trace() && irq_trace())
 504                 stop_critical_timing(CALLER_ADDR0, caller_addr);
 505 }
 506 EXPORT_SYMBOL(trace_hardirqs_on_caller);
 507
 508 void trace_hardirqs_off_caller(unsigned long caller_addr)
 509 {
 510         if (!preempt_trace() && irq_trace())
 511                 start_critical_timing(CALLER_ADDR0, caller_addr);
 512 }
 513 EXPORT_SYMBOL(trace_hardirqs_off_caller);
 514
 515 #endif /* CONFIG_PROVE_LOCKING */
 516 #endif /*  CONFIG_IRQSOFF_TRACER */
 517
 518 #ifdef CONFIG_PREEMPT_TRACER
 519 void trace_preempt_on(unsigned long a0, unsigned long a1)
 520 {
 521         if (preempt_trace() && !irq_trace())
 522                 stop_critical_timing(a0, a1);
 523 }
 524
 525 void trace_preempt_off(unsigned long a0, unsigned long a1)
 526 {
 527         if (preempt_trace() && !irq_trace())
 528                 start_critical_timing(a0, a1);
 529 }
 530 #endif /* CONFIG_PREEMPT_TRACER */
 531
 532 static int register_irqsoff_function(int graph, int set)
 533 {
 534         int ret;
 535
 536         /* 'set' is set if TRACE_ITER_FUNCTION is about to be set */
 537         if (function_enabled || (!set && !(trace_flags & TRACE_ITER_FUNCTION)))
 538                 return 0;
 539
 540         if (graph)
 541                 ret = register_ftrace_graph(&irqsoff_graph_return,
 542                                             &irqsoff_graph_entry);
 543         else
 544                 ret = register_ftrace_function(&trace_ops);
 545
 546         if (!ret)
 547                 function_enabled = true;
 548
 549         return ret;
 550 }
 551
 552 static void unregister_irqsoff_function(int graph)
 553 {
 554         if (!function_enabled)
 555                 return;
 556
 557         if (graph)
 558                 unregister_ftrace_graph();
 559         else
 560                 unregister_ftrace_function(&trace_ops);
 561
 562         function_enabled = false;
 563 }
 564
 565 static void irqsoff_function_set(int set)
 566 {
 567         if (set)
 568                 register_irqsoff_function(is_graph(), 1);
 569         else
 570                 unregister_irqsoff_function(is_graph());
 571 }
 572
 573 static int irqsoff_flag_changed(struct tracer *tracer, u32 mask, int set)
 574 {
 575         if (mask & TRACE_ITER_FUNCTION)
 576                 irqsoff_function_set(set);
 577
 578         return trace_keep_overwrite(tracer, mask, set);
 579 }
 580
 581 static int start_irqsoff_tracer(struct trace_array *tr, int graph)
 582 {
 583         int ret;
 584
 585         ret = register_irqsoff_function(graph, 0);
 586
 587         if (!ret && tracing_is_enabled())
 588                 tracer_enabled = 1;
 589         else
 590                 tracer_enabled = 0;
 591
 592         return ret;
 593 }
 594
 595 static void stop_irqsoff_tracer(struct trace_array *tr, int graph)
 596 {
 597         tracer_enabled = 0;
 598
 599         unregister_irqsoff_function(graph);
 600 }
 601
 602 static void __irqsoff_tracer_init(struct trace_array *tr)
 603 {
 604         save_flags = trace_flags;
 605
 606         /* non overwrite screws up the latency tracers */
 607         set_tracer_flag(tr, TRACE_ITER_OVERWRITE, 1);
 608         set_tracer_flag(tr, TRACE_ITER_LATENCY_FMT, 1);
 609
 610         tracing_max_latency = 0;
 611         irqsoff_trace = tr;
 612         /* make sure that the tracer is visible */
 613         smp_wmb();
 614         tracing_reset_online_cpus(&tr->trace_buffer);
 615
 616         if (start_irqsoff_tracer(tr, is_graph()))
 617                 printk(KERN_ERR "failed to start irqsoff tracer\n");
 618 }
 619
 620 static void irqsoff_tracer_reset(struct trace_array *tr)
 621 {
 622         int lat_flag = save_flags & TRACE_ITER_LATENCY_FMT;
 623         int overwrite_flag = save_flags & TRACE_ITER_OVERWRITE;
 624
 625         stop_irqsoff_tracer(tr, is_graph());
 626
 627         set_tracer_flag(tr, TRACE_ITER_LATENCY_FMT, lat_flag);
 628         set_tracer_flag(tr, TRACE_ITER_OVERWRITE, overwrite_flag);
 629 }
 630
 631 static void irqsoff_tracer_start(struct trace_array *tr)
 632 {
 633         tracer_enabled = 1;
 634 }
 635
 636 static void irqsoff_tracer_stop(struct trace_array *tr)
 637 {
 638         tracer_enabled = 0;
 639 }
 640
 641 #ifdef CONFIG_IRQSOFF_TRACER
 642 static int irqsoff_tracer_init(struct trace_array *tr)
 643 {
 644         trace_type = TRACER_IRQS_OFF;
 645
 646         __irqsoff_tracer_init(tr);
 647         return 0;
 648 }
 649 static struct tracer irqsoff_tracer __read_mostly =
 650 {
 651         .name           = "irqsoff",
 652         .init           = irqsoff_tracer_init,
 653         .reset          = irqsoff_tracer_reset,
 654         .start          = irqsoff_tracer_start,
 655         .stop           = irqsoff_tracer_stop,
 656         .print_max      = true,
 657         .print_header   = irqsoff_print_header,
 658         .print_line     = irqsoff_print_line,
 659         .flags          = &tracer_flags,
 660         .set_flag       = irqsoff_set_flag,
 661         .flag_changed   = irqsoff_flag_changed,
 662 #ifdef CONFIG_FTRACE_SELFTEST
 663         .selftest    = trace_selftest_startup_irqsoff,
 664 #endif
 665         .open           = irqsoff_trace_open,
 666         .close          = irqsoff_trace_close,
 667         .use_max_tr     = true,
 668 };
 669 # define register_irqsoff(trace) register_tracer(&trace)
 670 #else
 671 # define register_irqsoff(trace) do { } while (0)
 672 #endif
 673
 674 #ifdef CONFIG_PREEMPT_TRACER
 675 static int preemptoff_tracer_init(struct trace_array *tr)
 676 {
 677         trace_type = TRACER_PREEMPT_OFF;
 678
 679         __irqsoff_tracer_init(tr);
 680         return 0;
 681 }
 682
 683 static struct tracer preemptoff_tracer __read_mostly =
 684 {
 685         .name           = "preemptoff",
 686         .init           = preemptoff_tracer_init,
 687         .reset          = irqsoff_tracer_reset,
 688         .start          = irqsoff_tracer_start,
 689         .stop           = irqsoff_tracer_stop,
 690         .print_max      = true,
 691         .print_header   = irqsoff_print_header,
 692         .print_line     = irqsoff_print_line,
 693         .flags          = &tracer_flags,
 694         .set_flag       = irqsoff_set_flag,
 695         .flag_changed   = irqsoff_flag_changed,
 696 #ifdef CONFIG_FTRACE_SELFTEST
 697         .selftest    = trace_selftest_startup_preemptoff,
 698 #endif
 699         .open           = irqsoff_trace_open,
 700         .close          = irqsoff_trace_close,
 701         .use_max_tr     = true,
 702 };
 703 # define register_preemptoff(trace) register_tracer(&trace)
 704 #else
 705 # define register_preemptoff(trace) do { } while (0)
 706 #endif
 707
 708 #if defined(CONFIG_IRQSOFF_TRACER) && \
 709         defined(CONFIG_PREEMPT_TRACER)
 710
 711 static int preemptirqsoff_tracer_init(struct trace_array *tr)
 712 {
 713         trace_type = TRACER_IRQS_OFF | TRACER_PREEMPT_OFF;
 714
 715         __irqsoff_tracer_init(tr);
 716         return 0;
 717 }
 718
 719 static struct tracer preemptirqsoff_tracer __read_mostly =
 720 {
 721         .name           = "preemptirqsoff",
 722         .init           = preemptirqsoff_tracer_init,
 723         .reset          = irqsoff_tracer_reset,
 724         .start          = irqsoff_tracer_start,
 725         .stop           = irqsoff_tracer_stop,
 726         .print_max      = true,
 727         .print_header   = irqsoff_print_header,
 728         .print_line     = irqsoff_print_line,
 729         .flags          = &tracer_flags,
 730         .set_flag       = irqsoff_set_flag,
 731         .flag_changed   = irqsoff_flag_changed,
 732 #ifdef CONFIG_FTRACE_SELFTEST
 733         .selftest    = trace_selftest_startup_preemptirqsoff,
 734 #endif
 735         .open           = irqsoff_trace_open,
 736         .close          = irqsoff_trace_close,
 737         .use_max_tr     = true,
 738 };
 739
 740 # define register_preemptirqsoff(trace) register_tracer(&trace)
 741 #else
 742 # define register_preemptirqsoff(trace) do { } while (0)
 743 #endif
 744
 745 __init static int init_irqsoff_tracer(void)
 746 {
 747         register_irqsoff(irqsoff_tracer);
 748         register_preemptoff(preemptoff_tracer);
 749         register_preemptirqsoff(preemptirqsoff_tracer);
 750
 751         return 0;
 752 }
 753 core_initcall(init_irqsoff_tracer);