mm/hotplug: only free wait_table if it's allocated by vmalloc
[linux-2.6/cjktty.git] / kernel / trace / trace_irqsoff.c
blob443b25b43b4f60f3b58102daab06c6150f01ad64
1 /*
2 * trace irqs off critical timings
4 * Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com>
5 * Copyright (C) 2008 Ingo Molnar <mingo@redhat.com>
7 * From code in the latency_tracer, that is:
9 * Copyright (C) 2004-2006 Ingo Molnar
10 * Copyright (C) 2004 Nadia Yvette Chambers
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>
19 #include "trace.h"
21 static struct trace_array *irqsoff_trace __read_mostly;
22 static int tracer_enabled __read_mostly;
24 static DEFINE_PER_CPU(int, tracing_cpu);
26 static DEFINE_RAW_SPINLOCK(max_trace_lock);
28 enum {
29 TRACER_IRQS_OFF = (1 << 1),
30 TRACER_PREEMPT_OFF = (1 << 2),
33 static int trace_type __read_mostly;
35 static int save_flags;
37 static void stop_irqsoff_tracer(struct trace_array *tr, int graph);
38 static int start_irqsoff_tracer(struct trace_array *tr, int graph);
40 #ifdef CONFIG_PREEMPT_TRACER
41 static inline int
42 preempt_trace(void)
44 return ((trace_type & TRACER_PREEMPT_OFF) && preempt_count());
46 #else
47 # define preempt_trace() (0)
48 #endif
50 #ifdef CONFIG_IRQSOFF_TRACER
51 static inline int
52 irq_trace(void)
54 return ((trace_type & TRACER_IRQS_OFF) &&
55 irqs_disabled());
57 #else
58 # define irq_trace() (0)
59 #endif
61 #define TRACE_DISPLAY_GRAPH 1
63 static struct tracer_opt trace_opts[] = {
64 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
65 /* display latency trace as call graph */
66 { TRACER_OPT(display-graph, TRACE_DISPLAY_GRAPH) },
67 #endif
68 { } /* Empty entry */
71 static struct tracer_flags tracer_flags = {
72 .val = 0,
73 .opts = trace_opts,
76 #define is_graph() (tracer_flags.val & TRACE_DISPLAY_GRAPH)
79 * Sequence count - we record it when starting a measurement and
80 * skip the latency if the sequence has changed - some other section
81 * did a maximum and could disturb our measurement with serial console
82 * printouts, etc. Truly coinciding maximum latencies should be rare
83 * and what happens together happens separately as well, so this doesn't
84 * decrease the validity of the maximum found:
86 static __cacheline_aligned_in_smp unsigned long max_sequence;
88 #ifdef CONFIG_FUNCTION_TRACER
90 * Prologue for the preempt and irqs off function tracers.
92 * Returns 1 if it is OK to continue, and data->disabled is
93 * incremented.
94 * 0 if the trace is to be ignored, and data->disabled
95 * is kept the same.
97 * Note, this function is also used outside this ifdef but
98 * inside the #ifdef of the function graph tracer below.
99 * This is OK, since the function graph tracer is
100 * dependent on the function tracer.
102 static int func_prolog_dec(struct trace_array *tr,
103 struct trace_array_cpu **data,
104 unsigned long *flags)
106 long disabled;
107 int cpu;
110 * Does not matter if we preempt. We test the flags
111 * afterward, to see if irqs are disabled or not.
112 * If we preempt and get a false positive, the flags
113 * test will fail.
115 cpu = raw_smp_processor_id();
116 if (likely(!per_cpu(tracing_cpu, cpu)))
117 return 0;
119 local_save_flags(*flags);
120 /* slight chance to get a false positive on tracing_cpu */
121 if (!irqs_disabled_flags(*flags))
122 return 0;
124 *data = tr->data[cpu];
125 disabled = atomic_inc_return(&(*data)->disabled);
127 if (likely(disabled == 1))
128 return 1;
130 atomic_dec(&(*data)->disabled);
132 return 0;
136 * irqsoff uses its own tracer function to keep the overhead down:
138 static void
139 irqsoff_tracer_call(unsigned long ip, unsigned long parent_ip,
140 struct ftrace_ops *op, struct pt_regs *pt_regs)
142 struct trace_array *tr = irqsoff_trace;
143 struct trace_array_cpu *data;
144 unsigned long flags;
146 if (!func_prolog_dec(tr, &data, &flags))
147 return;
149 trace_function(tr, ip, parent_ip, flags, preempt_count());
151 atomic_dec(&data->disabled);
154 static struct ftrace_ops trace_ops __read_mostly =
156 .func = irqsoff_tracer_call,
157 .flags = FTRACE_OPS_FL_GLOBAL | FTRACE_OPS_FL_RECURSION_SAFE,
159 #endif /* CONFIG_FUNCTION_TRACER */
161 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
162 static int irqsoff_set_flag(u32 old_flags, u32 bit, int set)
164 int cpu;
166 if (!(bit & TRACE_DISPLAY_GRAPH))
167 return -EINVAL;
169 if (!(is_graph() ^ set))
170 return 0;
172 stop_irqsoff_tracer(irqsoff_trace, !set);
174 for_each_possible_cpu(cpu)
175 per_cpu(tracing_cpu, cpu) = 0;
177 tracing_max_latency = 0;
178 tracing_reset_online_cpus(irqsoff_trace);
180 return start_irqsoff_tracer(irqsoff_trace, set);
183 static int irqsoff_graph_entry(struct ftrace_graph_ent *trace)
185 struct trace_array *tr = irqsoff_trace;
186 struct trace_array_cpu *data;
187 unsigned long flags;
188 int ret;
189 int pc;
191 if (!func_prolog_dec(tr, &data, &flags))
192 return 0;
194 pc = preempt_count();
195 ret = __trace_graph_entry(tr, trace, flags, pc);
196 atomic_dec(&data->disabled);
198 return ret;
201 static void irqsoff_graph_return(struct ftrace_graph_ret *trace)
203 struct trace_array *tr = irqsoff_trace;
204 struct trace_array_cpu *data;
205 unsigned long flags;
206 int pc;
208 if (!func_prolog_dec(tr, &data, &flags))
209 return;
211 pc = preempt_count();
212 __trace_graph_return(tr, trace, flags, pc);
213 atomic_dec(&data->disabled);
216 static void irqsoff_trace_open(struct trace_iterator *iter)
218 if (is_graph())
219 graph_trace_open(iter);
223 static void irqsoff_trace_close(struct trace_iterator *iter)
225 if (iter->private)
226 graph_trace_close(iter);
229 #define GRAPH_TRACER_FLAGS (TRACE_GRAPH_PRINT_CPU | \
230 TRACE_GRAPH_PRINT_PROC | \
231 TRACE_GRAPH_PRINT_ABS_TIME | \
232 TRACE_GRAPH_PRINT_DURATION)
234 static enum print_line_t irqsoff_print_line(struct trace_iterator *iter)
237 * In graph mode call the graph tracer output function,
238 * otherwise go with the TRACE_FN event handler
240 if (is_graph())
241 return print_graph_function_flags(iter, GRAPH_TRACER_FLAGS);
243 return TRACE_TYPE_UNHANDLED;
246 static void irqsoff_print_header(struct seq_file *s)
248 if (is_graph())
249 print_graph_headers_flags(s, GRAPH_TRACER_FLAGS);
250 else
251 trace_default_header(s);
254 static void
255 __trace_function(struct trace_array *tr,
256 unsigned long ip, unsigned long parent_ip,
257 unsigned long flags, int pc)
259 if (is_graph())
260 trace_graph_function(tr, ip, parent_ip, flags, pc);
261 else
262 trace_function(tr, ip, parent_ip, flags, pc);
265 #else
266 #define __trace_function trace_function
268 static int irqsoff_set_flag(u32 old_flags, u32 bit, int set)
270 return -EINVAL;
273 static int irqsoff_graph_entry(struct ftrace_graph_ent *trace)
275 return -1;
278 static enum print_line_t irqsoff_print_line(struct trace_iterator *iter)
280 return TRACE_TYPE_UNHANDLED;
283 static void irqsoff_graph_return(struct ftrace_graph_ret *trace) { }
284 static void irqsoff_trace_open(struct trace_iterator *iter) { }
285 static void irqsoff_trace_close(struct trace_iterator *iter) { }
287 #ifdef CONFIG_FUNCTION_TRACER
288 static void irqsoff_print_header(struct seq_file *s)
290 trace_default_header(s);
292 #else
293 static void irqsoff_print_header(struct seq_file *s)
295 trace_latency_header(s);
297 #endif /* CONFIG_FUNCTION_TRACER */
298 #endif /* CONFIG_FUNCTION_GRAPH_TRACER */
301 * Should this new latency be reported/recorded?
303 static int report_latency(cycle_t delta)
305 if (tracing_thresh) {
306 if (delta < tracing_thresh)
307 return 0;
308 } else {
309 if (delta <= tracing_max_latency)
310 return 0;
312 return 1;
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)
321 cycle_t T0, T1, delta;
322 unsigned long flags;
323 int pc;
325 T0 = data->preempt_timestamp;
326 T1 = ftrace_now(cpu);
327 delta = T1-T0;
329 local_save_flags(flags);
331 pc = preempt_count();
333 if (!report_latency(delta))
334 goto out;
336 raw_spin_lock_irqsave(&max_trace_lock, flags);
338 /* check if we are still the max latency */
339 if (!report_latency(delta))
340 goto out_unlock;
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);
346 if (data->critical_sequence != max_sequence)
347 goto out_unlock;
349 data->critical_end = parent_ip;
351 if (likely(!is_tracing_stopped())) {
352 tracing_max_latency = delta;
353 update_max_tr_single(tr, current, cpu);
356 max_sequence++;
358 out_unlock:
359 raw_spin_unlock_irqrestore(&max_trace_lock, flags);
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);
367 static inline void
368 start_critical_timing(unsigned long ip, unsigned long parent_ip)
370 int cpu;
371 struct trace_array *tr = irqsoff_trace;
372 struct trace_array_cpu *data;
373 unsigned long flags;
375 if (likely(!tracer_enabled))
376 return;
378 cpu = raw_smp_processor_id();
380 if (per_cpu(tracing_cpu, cpu))
381 return;
383 data = tr->data[cpu];
385 if (unlikely(!data) || atomic_read(&data->disabled))
386 return;
388 atomic_inc(&data->disabled);
390 data->critical_sequence = max_sequence;
391 data->preempt_timestamp = ftrace_now(cpu);
392 data->critical_start = parent_ip ? : ip;
394 local_save_flags(flags);
396 __trace_function(tr, ip, parent_ip, flags, preempt_count());
398 per_cpu(tracing_cpu, cpu) = 1;
400 atomic_dec(&data->disabled);
403 static inline void
404 stop_critical_timing(unsigned long ip, unsigned long parent_ip)
406 int cpu;
407 struct trace_array *tr = irqsoff_trace;
408 struct trace_array_cpu *data;
409 unsigned long flags;
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;
418 if (!tracer_enabled)
419 return;
421 data = tr->data[cpu];
423 if (unlikely(!data) ||
424 !data->critical_start || atomic_read(&data->disabled))
425 return;
427 atomic_inc(&data->disabled);
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);
436 /* start and stop critical timings used to for stoppage (in idle) */
437 void start_critical_timings(void)
439 if (preempt_trace() || irq_trace())
440 start_critical_timing(CALLER_ADDR0, CALLER_ADDR1);
442 EXPORT_SYMBOL_GPL(start_critical_timings);
444 void stop_critical_timings(void)
446 if (preempt_trace() || irq_trace())
447 stop_critical_timing(CALLER_ADDR0, CALLER_ADDR1);
449 EXPORT_SYMBOL_GPL(stop_critical_timings);
451 #ifdef CONFIG_IRQSOFF_TRACER
452 #ifdef CONFIG_PROVE_LOCKING
453 void time_hardirqs_on(unsigned long a0, unsigned long a1)
455 if (!preempt_trace() && irq_trace())
456 stop_critical_timing(a0, a1);
459 void time_hardirqs_off(unsigned long a0, unsigned long a1)
461 if (!preempt_trace() && irq_trace())
462 start_critical_timing(a0, a1);
465 #else /* !CONFIG_PROVE_LOCKING */
468 * Stubs:
471 void trace_softirqs_on(unsigned long ip)
475 void trace_softirqs_off(unsigned long ip)
479 inline void print_irqtrace_events(struct task_struct *curr)
484 * We are only interested in hardirq on/off events:
486 void trace_hardirqs_on(void)
488 if (!preempt_trace() && irq_trace())
489 stop_critical_timing(CALLER_ADDR0, CALLER_ADDR1);
491 EXPORT_SYMBOL(trace_hardirqs_on);
493 void trace_hardirqs_off(void)
495 if (!preempt_trace() && irq_trace())
496 start_critical_timing(CALLER_ADDR0, CALLER_ADDR1);
498 EXPORT_SYMBOL(trace_hardirqs_off);
500 void trace_hardirqs_on_caller(unsigned long caller_addr)
502 if (!preempt_trace() && irq_trace())
503 stop_critical_timing(CALLER_ADDR0, caller_addr);
505 EXPORT_SYMBOL(trace_hardirqs_on_caller);
507 void trace_hardirqs_off_caller(unsigned long caller_addr)
509 if (!preempt_trace() && irq_trace())
510 start_critical_timing(CALLER_ADDR0, caller_addr);
512 EXPORT_SYMBOL(trace_hardirqs_off_caller);
514 #endif /* CONFIG_PROVE_LOCKING */
515 #endif /* CONFIG_IRQSOFF_TRACER */
517 #ifdef CONFIG_PREEMPT_TRACER
518 void trace_preempt_on(unsigned long a0, unsigned long a1)
520 if (preempt_trace() && !irq_trace())
521 stop_critical_timing(a0, a1);
524 void trace_preempt_off(unsigned long a0, unsigned long a1)
526 if (preempt_trace() && !irq_trace())
527 start_critical_timing(a0, a1);
529 #endif /* CONFIG_PREEMPT_TRACER */
531 static int start_irqsoff_tracer(struct trace_array *tr, int graph)
533 int ret = 0;
535 if (!graph)
536 ret = register_ftrace_function(&trace_ops);
537 else
538 ret = register_ftrace_graph(&irqsoff_graph_return,
539 &irqsoff_graph_entry);
541 if (!ret && tracing_is_enabled())
542 tracer_enabled = 1;
543 else
544 tracer_enabled = 0;
546 return ret;
549 static void stop_irqsoff_tracer(struct trace_array *tr, int graph)
551 tracer_enabled = 0;
553 if (!graph)
554 unregister_ftrace_function(&trace_ops);
555 else
556 unregister_ftrace_graph();
559 static void __irqsoff_tracer_init(struct trace_array *tr)
561 save_flags = trace_flags;
563 /* non overwrite screws up the latency tracers */
564 set_tracer_flag(TRACE_ITER_OVERWRITE, 1);
565 set_tracer_flag(TRACE_ITER_LATENCY_FMT, 1);
567 tracing_max_latency = 0;
568 irqsoff_trace = tr;
569 /* make sure that the tracer is visible */
570 smp_wmb();
571 tracing_reset_online_cpus(tr);
573 if (start_irqsoff_tracer(tr, is_graph()))
574 printk(KERN_ERR "failed to start irqsoff tracer\n");
577 static void irqsoff_tracer_reset(struct trace_array *tr)
579 int lat_flag = save_flags & TRACE_ITER_LATENCY_FMT;
580 int overwrite_flag = save_flags & TRACE_ITER_OVERWRITE;
582 stop_irqsoff_tracer(tr, is_graph());
584 set_tracer_flag(TRACE_ITER_LATENCY_FMT, lat_flag);
585 set_tracer_flag(TRACE_ITER_OVERWRITE, overwrite_flag);
588 static void irqsoff_tracer_start(struct trace_array *tr)
590 tracer_enabled = 1;
593 static void irqsoff_tracer_stop(struct trace_array *tr)
595 tracer_enabled = 0;
598 #ifdef CONFIG_IRQSOFF_TRACER
599 static int irqsoff_tracer_init(struct trace_array *tr)
601 trace_type = TRACER_IRQS_OFF;
603 __irqsoff_tracer_init(tr);
604 return 0;
606 static struct tracer irqsoff_tracer __read_mostly =
608 .name = "irqsoff",
609 .init = irqsoff_tracer_init,
610 .reset = irqsoff_tracer_reset,
611 .start = irqsoff_tracer_start,
612 .stop = irqsoff_tracer_stop,
613 .print_max = true,
614 .print_header = irqsoff_print_header,
615 .print_line = irqsoff_print_line,
616 .flags = &tracer_flags,
617 .set_flag = irqsoff_set_flag,
618 .flag_changed = trace_keep_overwrite,
619 #ifdef CONFIG_FTRACE_SELFTEST
620 .selftest = trace_selftest_startup_irqsoff,
621 #endif
622 .open = irqsoff_trace_open,
623 .close = irqsoff_trace_close,
624 .use_max_tr = true,
626 # define register_irqsoff(trace) register_tracer(&trace)
627 #else
628 # define register_irqsoff(trace) do { } while (0)
629 #endif
631 #ifdef CONFIG_PREEMPT_TRACER
632 static int preemptoff_tracer_init(struct trace_array *tr)
634 trace_type = TRACER_PREEMPT_OFF;
636 __irqsoff_tracer_init(tr);
637 return 0;
640 static struct tracer preemptoff_tracer __read_mostly =
642 .name = "preemptoff",
643 .init = preemptoff_tracer_init,
644 .reset = irqsoff_tracer_reset,
645 .start = irqsoff_tracer_start,
646 .stop = irqsoff_tracer_stop,
647 .print_max = true,
648 .print_header = irqsoff_print_header,
649 .print_line = irqsoff_print_line,
650 .flags = &tracer_flags,
651 .set_flag = irqsoff_set_flag,
652 .flag_changed = trace_keep_overwrite,
653 #ifdef CONFIG_FTRACE_SELFTEST
654 .selftest = trace_selftest_startup_preemptoff,
655 #endif
656 .open = irqsoff_trace_open,
657 .close = irqsoff_trace_close,
658 .use_max_tr = true,
660 # define register_preemptoff(trace) register_tracer(&trace)
661 #else
662 # define register_preemptoff(trace) do { } while (0)
663 #endif
665 #if defined(CONFIG_IRQSOFF_TRACER) && \
666 defined(CONFIG_PREEMPT_TRACER)
668 static int preemptirqsoff_tracer_init(struct trace_array *tr)
670 trace_type = TRACER_IRQS_OFF | TRACER_PREEMPT_OFF;
672 __irqsoff_tracer_init(tr);
673 return 0;
676 static struct tracer preemptirqsoff_tracer __read_mostly =
678 .name = "preemptirqsoff",
679 .init = preemptirqsoff_tracer_init,
680 .reset = irqsoff_tracer_reset,
681 .start = irqsoff_tracer_start,
682 .stop = irqsoff_tracer_stop,
683 .print_max = true,
684 .print_header = irqsoff_print_header,
685 .print_line = irqsoff_print_line,
686 .flags = &tracer_flags,
687 .set_flag = irqsoff_set_flag,
688 .flag_changed = trace_keep_overwrite,
689 #ifdef CONFIG_FTRACE_SELFTEST
690 .selftest = trace_selftest_startup_preemptirqsoff,
691 #endif
692 .open = irqsoff_trace_open,
693 .close = irqsoff_trace_close,
694 .use_max_tr = true,
697 # define register_preemptirqsoff(trace) register_tracer(&trace)
698 #else
699 # define register_preemptirqsoff(trace) do { } while (0)
700 #endif
702 __init static int init_irqsoff_tracer(void)
704 register_irqsoff(irqsoff_tracer);
705 register_preemptoff(preemptoff_tracer);
706 register_preemptirqsoff(preemptirqsoff_tracer);
708 return 0;
710 core_initcall(init_irqsoff_tracer);