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/uaccess.h>
  14 #include <linux/module.h>
  15 #include <linux/ftrace.h>
  16
  17 #include "trace.h"
  18
  19 static struct trace_array               *irqsoff_trace __read_mostly;
  20 static int                              tracer_enabled __read_mostly;
  21
  22 static DEFINE_PER_CPU(int, tracing_cpu);
  23
  24 static DEFINE_RAW_SPINLOCK(max_trace_lock);
  25
  26 enum {
  27         TRACER_IRQS_OFF         = (1 << 1),
  28         TRACER_PREEMPT_OFF      = (1 << 2),
  29 };
  30
  31 static int trace_type __read_mostly;
  32
  33 static int save_flags;
  34
  35 static void stop_irqsoff_tracer(struct trace_array *tr, int graph);
  36 static int start_irqsoff_tracer(struct trace_array *tr, int graph);
  37
  38 #ifdef CONFIG_PREEMPT_TRACER
  39 static inline int
  40 preempt_trace(void)
  41 {
  42         return ((trace_type & TRACER_PREEMPT_OFF) && preempt_count());
  43 }
  44 #else
  45 # define preempt_trace() (0)
  46 #endif
  47
  48 #ifdef CONFIG_IRQSOFF_TRACER
  49 static inline int
  50 irq_trace(void)
  51 {
  52         return ((trace_type & TRACER_IRQS_OFF) &&
  53                 irqs_disabled());
  54 }
  55 #else
  56 # define irq_trace() (0)
  57 #endif
  58
  59 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
  60 static int irqsoff_display_graph(struct trace_array *tr, int set);
  61 # define is_graph(tr) ((tr)->trace_flags & TRACE_ITER_DISPLAY_GRAPH)
  62 #else
  63 static inline int irqsoff_display_graph(struct trace_array *tr, int set)
  64 {
  65         return -EINVAL;
  66 }
  67 # define is_graph(tr) false
  68 #endif
  69
  70 /*
  71  * Sequence count - we record it when starting a measurement and
  72  * skip the latency if the sequence has changed - some other section
  73  * did a maximum and could disturb our measurement with serial console
  74  * printouts, etc. Truly coinciding maximum latencies should be rare
  75  * and what happens together happens separately as well, so this doesn't
  76  * decrease the validity of the maximum found:
  77  */
  78 static __cacheline_aligned_in_smp       unsigned long max_sequence;
  79
  80 #ifdef CONFIG_FUNCTION_TRACER
  81 /*
  82  * Prologue for the preempt and irqs off function tracers.
  83  *
  84  * Returns 1 if it is OK to continue, and data->disabled is
  85  *            incremented.
  86  *         0 if the trace is to be ignored, and data->disabled
  87  *            is kept the same.
  88  *
  89  * Note, this function is also used outside this ifdef but
  90  *  inside the #ifdef of the function graph tracer below.
  91  *  This is OK, since the function graph tracer is
  92  *  dependent on the function tracer.
  93  */
  94 static int func_prolog_dec(struct trace_array *tr,
  95                            struct trace_array_cpu **data,
  96                            unsigned long *flags)
  97 {
  98         long disabled;
  99         int cpu;
 100
 101         /*
 102          * Does not matter if we preempt. We test the flags
 103          * afterward, to see if irqs are disabled or not.
 104          * If we preempt and get a false positive, the flags
 105          * test will fail.
 106          */
 107         cpu = raw_smp_processor_id();
 108         if (likely(!per_cpu(tracing_cpu, cpu)))
 109                 return 0;
 110
 111         local_save_flags(*flags);
 112         /*
 113          * Slight chance to get a false positive on tracing_cpu,
 114          * although I'm starting to think there isn't a chance.
 115          * Leave this for now just to be paranoid.
 116          */
 117         if (!irqs_disabled_flags(*flags) && !preempt_count())
 118                 return 0;
 119
 120         *data = per_cpu_ptr(tr->trace_buffer.data, cpu);
 121         disabled = atomic_inc_return(&(*data)->disabled);
 122
 123         if (likely(disabled == 1))
 124                 return 1;
 125
 126         atomic_dec(&(*data)->disabled);
 127
 128         return 0;
 129 }
 130
 131 /*
 132  * irqsoff uses its own tracer function to keep the overhead down:
 133  */
 134 static void
 135 irqsoff_tracer_call(unsigned long ip, unsigned long parent_ip,
 136                     struct ftrace_ops *op, struct pt_regs *pt_regs)
 137 {
 138         struct trace_array *tr = irqsoff_trace;
 139         struct trace_array_cpu *data;
 140         unsigned long flags;
 141
 142         if (!func_prolog_dec(tr, &data, &flags))
 143                 return;
 144
 145         trace_function(tr, ip, parent_ip, flags, preempt_count());
 146
 147         atomic_dec(&data->disabled);
 148 }
 149 #endif /* CONFIG_FUNCTION_TRACER */
 150
 151 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
 152 static int irqsoff_display_graph(struct trace_array *tr, int set)
 153 {
 154         int cpu;
 155
 156         if (!(is_graph(tr) ^ set))
 157                 return 0;
 158
 159         stop_irqsoff_tracer(irqsoff_trace, !set);
 160
 161         for_each_possible_cpu(cpu)
 162                 per_cpu(tracing_cpu, cpu) = 0;
 163
 164         tr->max_latency = 0;
 165         tracing_reset_online_cpus(&irqsoff_trace->trace_buffer);
 166
 167         return start_irqsoff_tracer(irqsoff_trace, set);
 168 }
 169
 170 static int irqsoff_graph_entry(struct ftrace_graph_ent *trace)
 171 {
 172         struct trace_array *tr = irqsoff_trace;
 173         struct trace_array_cpu *data;
 174         unsigned long flags;
 175         int ret;
 176         int pc;
 177
 178         if (ftrace_graph_ignore_func(trace))
 179                 return 0;
 180         /*
 181          * Do not trace a function if it's filtered by set_graph_notrace.
 182          * Make the index of ret stack negative to indicate that it should
 183          * ignore further functions.  But it needs its own ret stack entry
 184          * to recover the original index in order to continue tracing after
 185          * returning from the function.
 186          */
 187         if (ftrace_graph_notrace_addr(trace->func))
 188                 return 1;
 189
 190         if (!func_prolog_dec(tr, &data, &flags))
 191                 return 0;
 192
 193         pc = preempt_count();
 194         ret = __trace_graph_entry(tr, trace, flags, pc);
 195         atomic_dec(&data->disabled);
 196
 197         return ret;
 198 }
 199
 200 static void irqsoff_graph_return(struct ftrace_graph_ret *trace)
 201 {
 202         struct trace_array *tr = irqsoff_trace;
 203         struct trace_array_cpu *data;
 204         unsigned long flags;
 205         int pc;
 206
 207         ftrace_graph_addr_finish(trace);
 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(iter->tr))
 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(iter->tr))
 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         struct trace_array *tr = irqsoff_trace;
 250
 251         if (is_graph(tr))
 252                 print_graph_headers_flags(s, GRAPH_TRACER_FLAGS);
 253         else
 254                 trace_default_header(s);
 255 }
 256
 257 static void
 258 __trace_function(struct trace_array *tr,
 259                  unsigned long ip, unsigned long parent_ip,
 260                  unsigned long flags, int pc)
 261 {
 262         if (is_graph(tr))
 263                 trace_graph_function(tr, ip, parent_ip, flags, pc);
 264         else
 265                 trace_function(tr, ip, parent_ip, flags, pc);
 266 }
 267
 268 #else
 269 #define __trace_function trace_function
 270
 271 #ifdef CONFIG_FUNCTION_TRACER
 272 static int irqsoff_graph_entry(struct ftrace_graph_ent *trace)
 273 {
 274         return -1;
 275 }
 276 #endif
 277
 278 static enum print_line_t irqsoff_print_line(struct trace_iterator *iter)
 279 {
 280         return TRACE_TYPE_UNHANDLED;
 281 }
 282
 283 static void irqsoff_trace_open(struct trace_iterator *iter) { }
 284 static void irqsoff_trace_close(struct trace_iterator *iter) { }
 285
 286 #ifdef CONFIG_FUNCTION_TRACER
 287 static void irqsoff_graph_return(struct ftrace_graph_ret *trace) { }
 288 static void irqsoff_print_header(struct seq_file *s)
 289 {
 290         trace_default_header(s);
 291 }
 292 #else
 293 static void irqsoff_print_header(struct seq_file *s)
 294 {
 295         trace_latency_header(s);
 296 }
 297 #endif /* CONFIG_FUNCTION_TRACER */
 298 #endif /* CONFIG_FUNCTION_GRAPH_TRACER */
 299
 300 /*
 301  * Should this new latency be reported/recorded?
 302  */
 303 static bool report_latency(struct trace_array *tr, u64 delta)
 304 {
 305         if (tracing_thresh) {
 306                 if (delta < tracing_thresh)
 307                         return false;
 308         } else {
 309                 if (delta <= tr->max_latency)
 310                         return false;
 311         }
 312         return true;
 313 }
 314
 315 static void
 316 check_critical_timing(struct trace_array *tr,
 317                       struct trace_array_cpu *data,
 318                       unsigned long parent_ip,
 319                       int cpu)
 320 {
 321         u64 T0, T1, delta;
 322         unsigned long flags;
 323         int pc;
 324
 325         T0 = data->preempt_timestamp;
 326         T1 = ftrace_now(cpu);
 327         delta = T1-T0;
 328
 329         local_save_flags(flags);
 330
 331         pc = preempt_count();
 332
 333         if (!report_latency(tr, delta))
 334                 goto out;
 335
 336         raw_spin_lock_irqsave(&max_trace_lock, flags);
 337
 338         /* check if we are still the max latency */
 339         if (!report_latency(tr, delta))
 340                 goto out_unlock;
 341
 342         __trace_function(tr, CALLER_ADDR0, parent_ip, flags, pc);
 343         /* Skip 5 functions to get to the irq/preempt enable function */
 344         __trace_stack(tr, flags, 5, pc);
 345
 346         if (data->critical_sequence != max_sequence)
 347                 goto out_unlock;
 348
 349         data->critical_end = parent_ip;
 350
 351         if (likely(!is_tracing_stopped())) {
 352                 tr->max_latency = delta;
 353                 update_max_tr_single(tr, current, cpu);
 354         }
 355
 356         max_sequence++;
 357
 358 out_unlock:
 359         raw_spin_unlock_irqrestore(&max_trace_lock, flags);
 360
 361 out:
 362         data->critical_sequence = max_sequence;
 363         data->preempt_timestamp = ftrace_now(cpu);
 364         __trace_function(tr, CALLER_ADDR0, parent_ip, flags, pc);
 365 }
 366
 367 static inline void
 368 start_critical_timing(unsigned long ip, unsigned long parent_ip)
 369 {
 370         int cpu;
 371         struct trace_array *tr = irqsoff_trace;
 372         struct trace_array_cpu *data;
 373         unsigned long flags;
 374
 375         if (!tracer_enabled || !tracing_is_enabled())
 376                 return;
 377
 378         cpu = raw_smp_processor_id();
 379
 380         if (per_cpu(tracing_cpu, cpu))
 381                 return;
 382
 383         data = per_cpu_ptr(tr->trace_buffer.data, cpu);
 384
 385         if (unlikely(!data) || atomic_read(&data->disabled))
 386                 return;
 387
 388         atomic_inc(&data->disabled);
 389
 390         data->critical_sequence = max_sequence;
 391         data->preempt_timestamp = ftrace_now(cpu);
 392         data->critical_start = parent_ip ? : ip;
 393
 394         local_save_flags(flags);
 395
 396         __trace_function(tr, ip, parent_ip, flags, preempt_count());
 397
 398         per_cpu(tracing_cpu, cpu) = 1;
 399
 400         atomic_dec(&data->disabled);
 401 }
 402
 403 static inline void
 404 stop_critical_timing(unsigned long ip, unsigned long parent_ip)
 405 {
 406         int cpu;
 407         struct trace_array *tr = irqsoff_trace;
 408         struct trace_array_cpu *data;
 409         unsigned long flags;
 410
 411         cpu = raw_smp_processor_id();
 412         /* Always clear the tracing cpu on stopping the trace */
 413         if (unlikely(per_cpu(tracing_cpu, cpu)))
 414                 per_cpu(tracing_cpu, cpu) = 0;
 415         else
 416                 return;
 417
 418         if (!tracer_enabled || !tracing_is_enabled())
 419                 return;
 420
 421         data = per_cpu_ptr(tr->trace_buffer.data, cpu);
 422
 423         if (unlikely(!data) ||
 424             !data->critical_start || atomic_read(&data->disabled))
 425                 return;
 426
 427         atomic_inc(&data->disabled);
 428
 429         local_save_flags(flags);
 430         __trace_function(tr, ip, parent_ip, flags, preempt_count());
 431         check_critical_timing(tr, data, parent_ip ? : ip, cpu);
 432         data->critical_start = 0;
 433         atomic_dec(&data->disabled);
 434 }
 435
 436 /* start and stop critical timings used to for stoppage (in idle) */
 437 void start_critical_timings(void)
 438 {
 439         if (preempt_trace() || irq_trace())
 440                 start_critical_timing(CALLER_ADDR0, CALLER_ADDR1);
 441 }
 442 EXPORT_SYMBOL_GPL(start_critical_timings);
 443
 444 void stop_critical_timings(void)
 445 {
 446         if (preempt_trace() || irq_trace())
 447                 stop_critical_timing(CALLER_ADDR0, CALLER_ADDR1);
 448 }
 449 EXPORT_SYMBOL_GPL(stop_critical_timings);
 450
 451 #ifdef CONFIG_IRQSOFF_TRACER
 452 #ifdef CONFIG_PROVE_LOCKING
 453 void time_hardirqs_on(unsigned long a0, unsigned long a1)
 454 {
 455         if (!preempt_trace() && irq_trace())
 456                 stop_critical_timing(a0, a1);
 457 }
 458
 459 void time_hardirqs_off(unsigned long a0, unsigned long a1)
 460 {
 461         if (!preempt_trace() && irq_trace())
 462                 start_critical_timing(a0, a1);
 463 }
 464
 465 #else /* !CONFIG_PROVE_LOCKING */
 466
 467 /*
 468  * Stubs:
 469  */
 470
 471 void trace_softirqs_on(unsigned long ip)
 472 {
 473 }
 474
 475 void trace_softirqs_off(unsigned long ip)
 476 {
 477 }
 478
 479 inline void print_irqtrace_events(struct task_struct *curr)
 480 {
 481 }
 482
 483 /*
 484  * We are only interested in hardirq on/off events:
 485  */
 486 void trace_hardirqs_on(void)
 487 {
 488         if (!preempt_trace() && irq_trace())
 489                 stop_critical_timing(CALLER_ADDR0, CALLER_ADDR1);
 490 }
 491 EXPORT_SYMBOL(trace_hardirqs_on);
 492
 493 void trace_hardirqs_off(void)
 494 {
 495         if (!preempt_trace() && irq_trace())
 496                 start_critical_timing(CALLER_ADDR0, CALLER_ADDR1);
 497 }
 498 EXPORT_SYMBOL(trace_hardirqs_off);
 499
 500 __visible void trace_hardirqs_on_caller(unsigned long caller_addr)
 501 {
 502         if (!preempt_trace() && irq_trace())
 503                 stop_critical_timing(CALLER_ADDR0, caller_addr);
 504 }
 505 EXPORT_SYMBOL(trace_hardirqs_on_caller);
 506
 507 __visible void trace_hardirqs_off_caller(unsigned long caller_addr)
 508 {
 509         if (!preempt_trace() && irq_trace())
 510                 start_critical_timing(CALLER_ADDR0, caller_addr);
 511 }
 512 EXPORT_SYMBOL(trace_hardirqs_off_caller);
 513
 514 #endif /* CONFIG_PROVE_LOCKING */
 515 #endif /*  CONFIG_IRQSOFF_TRACER */
 516
 517 #ifdef CONFIG_PREEMPT_TRACER
 518 void trace_preempt_on(unsigned long a0, unsigned long a1)
 519 {
 520         if (preempt_trace() && !irq_trace())
 521                 stop_critical_timing(a0, a1);
 522 }
 523
 524 void trace_preempt_off(unsigned long a0, unsigned long a1)
 525 {
 526         if (preempt_trace() && !irq_trace())
 527                 start_critical_timing(a0, a1);
 528 }
 529 #endif /* CONFIG_PREEMPT_TRACER */
 530
 531 #ifdef CONFIG_FUNCTION_TRACER
 532 static bool function_enabled;
 533
 534 static int register_irqsoff_function(struct trace_array *tr, int graph, int set)
 535 {
 536         int ret;
 537
 538         /* 'set' is set if TRACE_ITER_FUNCTION is about to be set */
 539         if (function_enabled || (!set && !(tr->trace_flags & TRACE_ITER_FUNCTION)))
 540                 return 0;
 541
 542         if (graph)
 543                 ret = register_ftrace_graph(&irqsoff_graph_return,
 544                                             &irqsoff_graph_entry);
 545         else
 546                 ret = register_ftrace_function(tr->ops);
 547
 548         if (!ret)
 549                 function_enabled = true;
 550
 551         return ret;
 552 }
 553
 554 static void unregister_irqsoff_function(struct trace_array *tr, int graph)
 555 {
 556         if (!function_enabled)
 557                 return;
 558
 559         if (graph)
 560                 unregister_ftrace_graph();
 561         else
 562                 unregister_ftrace_function(tr->ops);
 563
 564         function_enabled = false;
 565 }
 566
 567 static int irqsoff_function_set(struct trace_array *tr, u32 mask, int set)
 568 {
 569         if (!(mask & TRACE_ITER_FUNCTION))
 570                 return 0;
 571
 572         if (set)
 573                 register_irqsoff_function(tr, is_graph(tr), 1);
 574         else
 575                 unregister_irqsoff_function(tr, is_graph(tr));
 576         return 1;
 577 }
 578 #else
 579 static int register_irqsoff_function(struct trace_array *tr, int graph, int set)
 580 {
 581         return 0;
 582 }
 583 static void unregister_irqsoff_function(struct trace_array *tr, int graph) { }
 584 static inline int irqsoff_function_set(struct trace_array *tr, u32 mask, int set)
 585 {
 586         return 0;
 587 }
 588 #endif /* CONFIG_FUNCTION_TRACER */
 589
 590 static int irqsoff_flag_changed(struct trace_array *tr, u32 mask, int set)
 591 {
 592         struct tracer *tracer = tr->current_trace;
 593
 594         if (irqsoff_function_set(tr, mask, set))
 595                 return 0;
 596
 597 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
 598         if (mask & TRACE_ITER_DISPLAY_GRAPH)
 599                 return irqsoff_display_graph(tr, set);
 600 #endif
 601
 602         return trace_keep_overwrite(tracer, mask, set);
 603 }
 604
 605 static int start_irqsoff_tracer(struct trace_array *tr, int graph)
 606 {
 607         int ret;
 608
 609         ret = register_irqsoff_function(tr, graph, 0);
 610
 611         if (!ret && tracing_is_enabled())
 612                 tracer_enabled = 1;
 613         else
 614                 tracer_enabled = 0;
 615
 616         return ret;
 617 }
 618
 619 static void stop_irqsoff_tracer(struct trace_array *tr, int graph)
 620 {
 621         tracer_enabled = 0;
 622
 623         unregister_irqsoff_function(tr, graph);
 624 }
 625
 626 static bool irqsoff_busy;
 627
 628 static int __irqsoff_tracer_init(struct trace_array *tr)
 629 {
 630         if (irqsoff_busy)
 631                 return -EBUSY;
 632
 633         save_flags = tr->trace_flags;
 634
 635         /* non overwrite screws up the latency tracers */
 636         set_tracer_flag(tr, TRACE_ITER_OVERWRITE, 1);
 637         set_tracer_flag(tr, TRACE_ITER_LATENCY_FMT, 1);
 638
 639         tr->max_latency = 0;
 640         irqsoff_trace = tr;
 641         /* make sure that the tracer is visible */
 642         smp_wmb();
 643
 644         ftrace_init_array_ops(tr, irqsoff_tracer_call);
 645
 646         /* Only toplevel instance supports graph tracing */
 647         if (start_irqsoff_tracer(tr, (tr->flags & TRACE_ARRAY_FL_GLOBAL &&
 648                                       is_graph(tr))))
 649                 printk(KERN_ERR "failed to start irqsoff tracer\n");
 650
 651         irqsoff_busy = true;
 652         return 0;
 653 }
 654
 655 static void irqsoff_tracer_reset(struct trace_array *tr)
 656 {
 657         int lat_flag = save_flags & TRACE_ITER_LATENCY_FMT;
 658         int overwrite_flag = save_flags & TRACE_ITER_OVERWRITE;
 659
 660         stop_irqsoff_tracer(tr, is_graph(tr));
 661
 662         set_tracer_flag(tr, TRACE_ITER_LATENCY_FMT, lat_flag);
 663         set_tracer_flag(tr, TRACE_ITER_OVERWRITE, overwrite_flag);
 664         ftrace_reset_array_ops(tr);
 665
 666         irqsoff_busy = false;
 667 }
 668
 669 static void irqsoff_tracer_start(struct trace_array *tr)
 670 {
 671         tracer_enabled = 1;
 672 }
 673
 674 static void irqsoff_tracer_stop(struct trace_array *tr)
 675 {
 676         tracer_enabled = 0;
 677 }
 678
 679 #ifdef CONFIG_IRQSOFF_TRACER
 680 static int irqsoff_tracer_init(struct trace_array *tr)
 681 {
 682         trace_type = TRACER_IRQS_OFF;
 683
 684         return __irqsoff_tracer_init(tr);
 685 }
 686 static struct tracer irqsoff_tracer __read_mostly =
 687 {
 688         .name           = "irqsoff",
 689         .init           = irqsoff_tracer_init,
 690         .reset          = irqsoff_tracer_reset,
 691         .start          = irqsoff_tracer_start,
 692         .stop           = irqsoff_tracer_stop,
 693         .print_max      = true,
 694         .print_header   = irqsoff_print_header,
 695         .print_line     = irqsoff_print_line,
 696         .flag_changed   = irqsoff_flag_changed,
 697 #ifdef CONFIG_FTRACE_SELFTEST
 698         .selftest    = trace_selftest_startup_irqsoff,
 699 #endif
 700         .open           = irqsoff_trace_open,
 701         .close          = irqsoff_trace_close,
 702         .allow_instances = true,
 703         .use_max_tr     = true,
 704 };
 705 # define register_irqsoff(trace) register_tracer(&trace)
 706 #else
 707 # define register_irqsoff(trace) do { } while (0)
 708 #endif
 709
 710 #ifdef CONFIG_PREEMPT_TRACER
 711 static int preemptoff_tracer_init(struct trace_array *tr)
 712 {
 713         trace_type = TRACER_PREEMPT_OFF;
 714
 715         return __irqsoff_tracer_init(tr);
 716 }
 717
 718 static struct tracer preemptoff_tracer __read_mostly =
 719 {
 720         .name           = "preemptoff",
 721         .init           = preemptoff_tracer_init,
 722         .reset          = irqsoff_tracer_reset,
 723         .start          = irqsoff_tracer_start,
 724         .stop           = irqsoff_tracer_stop,
 725         .print_max      = true,
 726         .print_header   = irqsoff_print_header,
 727         .print_line     = irqsoff_print_line,
 728         .flag_changed   = irqsoff_flag_changed,
 729 #ifdef CONFIG_FTRACE_SELFTEST
 730         .selftest    = trace_selftest_startup_preemptoff,
 731 #endif
 732         .open           = irqsoff_trace_open,
 733         .close          = irqsoff_trace_close,
 734         .allow_instances = true,
 735         .use_max_tr     = true,
 736 };
 737 # define register_preemptoff(trace) register_tracer(&trace)
 738 #else
 739 # define register_preemptoff(trace) do { } while (0)
 740 #endif
 741
 742 #if defined(CONFIG_IRQSOFF_TRACER) && \
 743         defined(CONFIG_PREEMPT_TRACER)
 744
 745 static int preemptirqsoff_tracer_init(struct trace_array *tr)
 746 {
 747         trace_type = TRACER_IRQS_OFF | TRACER_PREEMPT_OFF;
 748
 749         return __irqsoff_tracer_init(tr);
 750 }
 751
 752 static struct tracer preemptirqsoff_tracer __read_mostly =
 753 {
 754         .name           = "preemptirqsoff",
 755         .init           = preemptirqsoff_tracer_init,
 756         .reset          = irqsoff_tracer_reset,
 757         .start          = irqsoff_tracer_start,
 758         .stop           = irqsoff_tracer_stop,
 759         .print_max      = true,
 760         .print_header   = irqsoff_print_header,
 761         .print_line     = irqsoff_print_line,
 762         .flag_changed   = irqsoff_flag_changed,
 763 #ifdef CONFIG_FTRACE_SELFTEST
 764         .selftest    = trace_selftest_startup_preemptirqsoff,
 765 #endif
 766         .open           = irqsoff_trace_open,
 767         .close          = irqsoff_trace_close,
 768         .allow_instances = true,
 769         .use_max_tr     = true,
 770 };
 771
 772 # define register_preemptirqsoff(trace) register_tracer(&trace)
 773 #else
 774 # define register_preemptirqsoff(trace) do { } while (0)
 775 #endif
 776
 777 __init static int init_irqsoff_tracer(void)
 778 {
 779         register_irqsoff(irqsoff_tracer);
 780         register_preemptoff(preemptoff_tracer);
 781         register_preemptirqsoff(preemptirqsoff_tracer);
 782
 783         return 0;
 784 }
 785 core_initcall(init_irqsoff_tracer);