2 * ring buffer based function tracer
4 * Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com>
5 * Copyright (C) 2008 Ingo Molnar <mingo@redhat.com>
7 * Originally taken from the RT patch by:
8 * Arnaldo Carvalho de Melo <acme@redhat.com>
10 * Based on code from the latency_tracer, that is:
11 * Copyright (C) 2004-2006 Ingo Molnar
12 * Copyright (C) 2004 William Lee Irwin III
14 #include <linux/utsrelease.h>
15 #include <linux/kallsyms.h>
16 #include <linux/seq_file.h>
17 #include <linux/debugfs.h>
18 #include <linux/pagemap.h>
19 #include <linux/hardirq.h>
20 #include <linux/linkage.h>
21 #include <linux/uaccess.h>
22 #include <linux/ftrace.h>
23 #include <linux/module.h>
24 #include <linux/percpu.h>
25 #include <linux/ctype.h>
26 #include <linux/init.h>
27 #include <linux/poll.h>
28 #include <linux/gfp.h>
31 #include <linux/stacktrace.h>
35 unsigned long __read_mostly tracing_max_latency = (cycle_t)ULONG_MAX;
36 unsigned long __read_mostly tracing_thresh;
38 static unsigned long __read_mostly tracing_nr_buffers;
39 static cpumask_t __read_mostly tracing_buffer_mask;
41 #define for_each_tracing_cpu(cpu) \
42 for_each_cpu_mask(cpu, tracing_buffer_mask)
44 /* dummy trace to disable tracing */
45 static struct tracer no_tracer __read_mostly = {
49 static int trace_alloc_page(void);
50 static int trace_free_page(void);
52 static int tracing_disabled = 1;
55 ns2usecs(cycle_t nsec)
62 cycle_t ftrace_now(int cpu)
64 return cpu_clock(cpu);
68 * The global_trace is the descriptor that holds the tracing
69 * buffers for the live tracing. For each CPU, it contains
70 * a link list of pages that will store trace entries. The
71 * page descriptor of the pages in the memory is used to hold
72 * the link list by linking the lru item in the page descriptor
73 * to each of the pages in the buffer per CPU.
75 * For each active CPU there is a data field that holds the
76 * pages for the buffer for that CPU. Each CPU has the same number
77 * of pages allocated for its buffer.
79 static struct trace_array global_trace;
81 static DEFINE_PER_CPU(struct trace_array_cpu, global_trace_cpu);
84 * The max_tr is used to snapshot the global_trace when a maximum
85 * latency is reached. Some tracers will use this to store a maximum
86 * trace while it continues examining live traces.
88 * The buffers for the max_tr are set up the same as the global_trace.
89 * When a snapshot is taken, the link list of the max_tr is swapped
90 * with the link list of the global_trace and the buffers are reset for
91 * the global_trace so the tracing can continue.
93 static struct trace_array max_tr;
95 static DEFINE_PER_CPU(struct trace_array_cpu, max_data);
97 /* tracer_enabled is used to toggle activation of a tracer */
98 static int tracer_enabled = 1;
101 * trace_nr_entries is the number of entries that is allocated
102 * for a buffer. Note, the number of entries is always rounded
103 * to ENTRIES_PER_PAGE.
105 static unsigned long trace_nr_entries = 65536UL;
107 /* trace_types holds a link list of available tracers. */
108 static struct tracer *trace_types __read_mostly;
110 /* current_trace points to the tracer that is currently active */
111 static struct tracer *current_trace __read_mostly;
114 * max_tracer_type_len is used to simplify the allocating of
115 * buffers to read userspace tracer names. We keep track of
116 * the longest tracer name registered.
118 static int max_tracer_type_len;
121 * trace_types_lock is used to protect the trace_types list.
122 * This lock is also used to keep user access serialized.
123 * Accesses from userspace will grab this lock while userspace
124 * activities happen inside the kernel.
126 static DEFINE_MUTEX(trace_types_lock);
128 /* trace_wait is a waitqueue for tasks blocked on trace_poll */
129 static DECLARE_WAIT_QUEUE_HEAD(trace_wait);
131 /* trace_flags holds iter_ctrl options */
132 unsigned long trace_flags = TRACE_ITER_PRINT_PARENT;
135 * trace_wake_up - wake up tasks waiting for trace input
137 * Simply wakes up any task that is blocked on the trace_wait
138 * queue. These is used with trace_poll for tasks polling the trace.
140 void trace_wake_up(void)
143 * The runqueue_is_locked() can fail, but this is the best we
146 if (!(trace_flags & TRACE_ITER_BLOCK) && !runqueue_is_locked())
147 wake_up(&trace_wait);
150 #define ENTRIES_PER_PAGE (PAGE_SIZE / sizeof(struct trace_entry))
152 static int __init set_nr_entries(char *str)
154 unsigned long nr_entries;
159 ret = strict_strtoul(str, 0, &nr_entries);
160 /* nr_entries can not be zero */
161 if (ret < 0 || nr_entries == 0)
163 trace_nr_entries = nr_entries;
166 __setup("trace_entries=", set_nr_entries);
168 unsigned long nsecs_to_usecs(unsigned long nsecs)
174 * trace_flag_type is an enumeration that holds different
175 * states when a trace occurs. These are:
176 * IRQS_OFF - interrupts were disabled
177 * NEED_RESCED - reschedule is requested
178 * HARDIRQ - inside an interrupt handler
179 * SOFTIRQ - inside a softirq handler
181 enum trace_flag_type {
182 TRACE_FLAG_IRQS_OFF = 0x01,
183 TRACE_FLAG_NEED_RESCHED = 0x02,
184 TRACE_FLAG_HARDIRQ = 0x04,
185 TRACE_FLAG_SOFTIRQ = 0x08,
189 * TRACE_ITER_SYM_MASK masks the options in trace_flags that
190 * control the output of kernel symbols.
192 #define TRACE_ITER_SYM_MASK \
193 (TRACE_ITER_PRINT_PARENT|TRACE_ITER_SYM_OFFSET|TRACE_ITER_SYM_ADDR)
195 /* These must match the bit postions in trace_iterator_flags */
196 static const char *trace_options[] = {
211 * ftrace_max_lock is used to protect the swapping of buffers
212 * when taking a max snapshot. The buffers themselves are
213 * protected by per_cpu spinlocks. But the action of the swap
214 * needs its own lock.
216 * This is defined as a raw_spinlock_t in order to help
217 * with performance when lockdep debugging is enabled.
219 static raw_spinlock_t ftrace_max_lock =
220 (raw_spinlock_t)__RAW_SPIN_LOCK_UNLOCKED;
223 * Copy the new maximum trace into the separate maximum-trace
224 * structure. (this way the maximum trace is permanently saved,
225 * for later retrieval via /debugfs/tracing/latency_trace)
228 __update_max_tr(struct trace_array *tr, struct task_struct *tsk, int cpu)
230 struct trace_array_cpu *data = tr->data[cpu];
233 max_tr.time_start = data->preempt_timestamp;
235 data = max_tr.data[cpu];
236 data->saved_latency = tracing_max_latency;
238 memcpy(data->comm, tsk->comm, TASK_COMM_LEN);
239 data->pid = tsk->pid;
240 data->uid = tsk->uid;
241 data->nice = tsk->static_prio - 20 - MAX_RT_PRIO;
242 data->policy = tsk->policy;
243 data->rt_priority = tsk->rt_priority;
245 /* record this tasks comm */
246 tracing_record_cmdline(current);
250 * check_pages - integrity check of trace buffers
252 * As a safty measure we check to make sure the data pages have not
253 * been corrupted. TODO: configure to disable this because it adds
256 void check_pages(struct trace_array_cpu *data)
258 struct page *page, *tmp;
260 BUG_ON(data->trace_pages.next->prev != &data->trace_pages);
261 BUG_ON(data->trace_pages.prev->next != &data->trace_pages);
263 list_for_each_entry_safe(page, tmp, &data->trace_pages, lru) {
264 BUG_ON(page->lru.next->prev != &page->lru);
265 BUG_ON(page->lru.prev->next != &page->lru);
270 * head_page - page address of the first page in per_cpu buffer.
272 * head_page returns the page address of the first page in
273 * a per_cpu buffer. This also preforms various consistency
274 * checks to make sure the buffer has not been corrupted.
276 void *head_page(struct trace_array_cpu *data)
281 if (list_empty(&data->trace_pages))
284 page = list_entry(data->trace_pages.next, struct page, lru);
285 BUG_ON(&page->lru == &data->trace_pages);
287 return page_address(page);
291 * trace_seq_printf - sequence printing of trace information
292 * @s: trace sequence descriptor
293 * @fmt: printf format string
295 * The tracer may use either sequence operations or its own
296 * copy to user routines. To simplify formating of a trace
297 * trace_seq_printf is used to store strings into a special
298 * buffer (@s). Then the output may be either used by
299 * the sequencer or pulled into another buffer.
302 trace_seq_printf(struct trace_seq *s, const char *fmt, ...)
304 int len = (PAGE_SIZE - 1) - s->len;
312 ret = vsnprintf(s->buffer + s->len, len, fmt, ap);
315 /* If we can't write it all, don't bother writing anything */
325 * trace_seq_puts - trace sequence printing of simple string
326 * @s: trace sequence descriptor
327 * @str: simple string to record
329 * The tracer may use either the sequence operations or its own
330 * copy to user routines. This function records a simple string
331 * into a special buffer (@s) for later retrieval by a sequencer
332 * or other mechanism.
335 trace_seq_puts(struct trace_seq *s, const char *str)
337 int len = strlen(str);
339 if (len > ((PAGE_SIZE - 1) - s->len))
342 memcpy(s->buffer + s->len, str, len);
349 trace_seq_putc(struct trace_seq *s, unsigned char c)
351 if (s->len >= (PAGE_SIZE - 1))
354 s->buffer[s->len++] = c;
360 trace_seq_putmem(struct trace_seq *s, void *mem, size_t len)
362 if (len > ((PAGE_SIZE - 1) - s->len))
365 memcpy(s->buffer + s->len, mem, len);
372 static const char hex2asc[] = "0123456789abcdef";
375 trace_seq_putmem_hex(struct trace_seq *s, void *mem, size_t len)
377 unsigned char hex[HEX_CHARS];
378 unsigned char *data = mem;
382 BUG_ON(len >= HEX_CHARS);
385 for (i = 0, j = 0; i < len; i++) {
387 for (i = len-1, j = 0; i >= 0; i--) {
391 hex[j++] = hex2asc[byte & 0x0f];
392 hex[j++] = hex2asc[byte >> 4];
396 return trace_seq_putmem(s, hex, j);
400 trace_seq_reset(struct trace_seq *s)
406 trace_print_seq(struct seq_file *m, struct trace_seq *s)
408 int len = s->len >= PAGE_SIZE ? PAGE_SIZE - 1 : s->len;
411 seq_puts(m, s->buffer);
417 * flip the trace buffers between two trace descriptors.
418 * This usually is the buffers between the global_trace and
419 * the max_tr to record a snapshot of a current trace.
421 * The ftrace_max_lock must be held.
424 flip_trace(struct trace_array_cpu *tr1, struct trace_array_cpu *tr2)
426 struct list_head flip_pages;
428 INIT_LIST_HEAD(&flip_pages);
430 memcpy(&tr1->trace_head_idx, &tr2->trace_head_idx,
431 sizeof(struct trace_array_cpu) -
432 offsetof(struct trace_array_cpu, trace_head_idx));
436 list_splice_init(&tr1->trace_pages, &flip_pages);
437 list_splice_init(&tr2->trace_pages, &tr1->trace_pages);
438 list_splice_init(&flip_pages, &tr2->trace_pages);
439 BUG_ON(!list_empty(&flip_pages));
445 * update_max_tr - snapshot all trace buffers from global_trace to max_tr
447 * @tsk: the task with the latency
448 * @cpu: The cpu that initiated the trace.
450 * Flip the buffers between the @tr and the max_tr and record information
451 * about which task was the cause of this latency.
454 update_max_tr(struct trace_array *tr, struct task_struct *tsk, int cpu)
456 struct trace_array_cpu *data;
459 WARN_ON_ONCE(!irqs_disabled());
460 __raw_spin_lock(&ftrace_max_lock);
461 /* clear out all the previous traces */
462 for_each_tracing_cpu(i) {
464 flip_trace(max_tr.data[i], data);
468 __update_max_tr(tr, tsk, cpu);
469 __raw_spin_unlock(&ftrace_max_lock);
473 * update_max_tr_single - only copy one trace over, and reset the rest
475 * @tsk - task with the latency
476 * @cpu - the cpu of the buffer to copy.
478 * Flip the trace of a single CPU buffer between the @tr and the max_tr.
481 update_max_tr_single(struct trace_array *tr, struct task_struct *tsk, int cpu)
483 struct trace_array_cpu *data = tr->data[cpu];
486 WARN_ON_ONCE(!irqs_disabled());
487 __raw_spin_lock(&ftrace_max_lock);
488 for_each_tracing_cpu(i)
489 tracing_reset(max_tr.data[i]);
491 flip_trace(max_tr.data[cpu], data);
494 __update_max_tr(tr, tsk, cpu);
495 __raw_spin_unlock(&ftrace_max_lock);
499 * register_tracer - register a tracer with the ftrace system.
500 * @type - the plugin for the tracer
502 * Register a new plugin tracer.
504 int register_tracer(struct tracer *type)
511 pr_info("Tracer must have a name\n");
515 mutex_lock(&trace_types_lock);
516 for (t = trace_types; t; t = t->next) {
517 if (strcmp(type->name, t->name) == 0) {
519 pr_info("Trace %s already registered\n",
526 #ifdef CONFIG_FTRACE_STARTUP_TEST
527 if (type->selftest) {
528 struct tracer *saved_tracer = current_trace;
529 struct trace_array_cpu *data;
530 struct trace_array *tr = &global_trace;
531 int saved_ctrl = tr->ctrl;
534 * Run a selftest on this tracer.
535 * Here we reset the trace buffer, and set the current
536 * tracer to be this tracer. The tracer can then run some
537 * internal tracing to verify that everything is in order.
538 * If we fail, we do not register this tracer.
540 for_each_tracing_cpu(i) {
542 if (!head_page(data))
546 current_trace = type;
548 /* the test is responsible for initializing and enabling */
549 pr_info("Testing tracer %s: ", type->name);
550 ret = type->selftest(type, tr);
551 /* the test is responsible for resetting too */
552 current_trace = saved_tracer;
553 tr->ctrl = saved_ctrl;
555 printk(KERN_CONT "FAILED!\n");
558 /* Only reset on passing, to avoid touching corrupted buffers */
559 for_each_tracing_cpu(i) {
561 if (!head_page(data))
565 printk(KERN_CONT "PASSED\n");
569 type->next = trace_types;
571 len = strlen(type->name);
572 if (len > max_tracer_type_len)
573 max_tracer_type_len = len;
576 mutex_unlock(&trace_types_lock);
581 void unregister_tracer(struct tracer *type)
586 mutex_lock(&trace_types_lock);
587 for (t = &trace_types; *t; t = &(*t)->next) {
591 pr_info("Trace %s not registered\n", type->name);
596 if (strlen(type->name) != max_tracer_type_len)
599 max_tracer_type_len = 0;
600 for (t = &trace_types; *t; t = &(*t)->next) {
601 len = strlen((*t)->name);
602 if (len > max_tracer_type_len)
603 max_tracer_type_len = len;
606 mutex_unlock(&trace_types_lock);
609 void tracing_reset(struct trace_array_cpu *data)
612 data->trace_head = data->trace_tail = head_page(data);
613 data->trace_head_idx = 0;
614 data->trace_tail_idx = 0;
617 #define SAVED_CMDLINES 128
618 static unsigned map_pid_to_cmdline[PID_MAX_DEFAULT+1];
619 static unsigned map_cmdline_to_pid[SAVED_CMDLINES];
620 static char saved_cmdlines[SAVED_CMDLINES][TASK_COMM_LEN];
621 static int cmdline_idx;
622 static DEFINE_SPINLOCK(trace_cmdline_lock);
623 atomic_t trace_record_cmdline_disabled;
625 static void trace_init_cmdlines(void)
627 memset(&map_pid_to_cmdline, -1, sizeof(map_pid_to_cmdline));
628 memset(&map_cmdline_to_pid, -1, sizeof(map_cmdline_to_pid));
632 void trace_stop_cmdline_recording(void);
634 static void trace_save_cmdline(struct task_struct *tsk)
639 if (!tsk->pid || unlikely(tsk->pid > PID_MAX_DEFAULT))
643 * It's not the end of the world if we don't get
644 * the lock, but we also don't want to spin
645 * nor do we want to disable interrupts,
646 * so if we miss here, then better luck next time.
648 if (!spin_trylock(&trace_cmdline_lock))
651 idx = map_pid_to_cmdline[tsk->pid];
652 if (idx >= SAVED_CMDLINES) {
653 idx = (cmdline_idx + 1) % SAVED_CMDLINES;
655 map = map_cmdline_to_pid[idx];
656 if (map <= PID_MAX_DEFAULT)
657 map_pid_to_cmdline[map] = (unsigned)-1;
659 map_pid_to_cmdline[tsk->pid] = idx;
664 memcpy(&saved_cmdlines[idx], tsk->comm, TASK_COMM_LEN);
666 spin_unlock(&trace_cmdline_lock);
669 static char *trace_find_cmdline(int pid)
671 char *cmdline = "<...>";
677 if (pid > PID_MAX_DEFAULT)
680 map = map_pid_to_cmdline[pid];
681 if (map >= SAVED_CMDLINES)
684 cmdline = saved_cmdlines[map];
690 void tracing_record_cmdline(struct task_struct *tsk)
692 if (atomic_read(&trace_record_cmdline_disabled))
695 trace_save_cmdline(tsk);
698 static inline struct list_head *
699 trace_next_list(struct trace_array_cpu *data, struct list_head *next)
702 * Roundrobin - but skip the head (which is not a real page):
705 if (unlikely(next == &data->trace_pages))
707 BUG_ON(next == &data->trace_pages);
713 trace_next_page(struct trace_array_cpu *data, void *addr)
715 struct list_head *next;
718 page = virt_to_page(addr);
720 next = trace_next_list(data, &page->lru);
721 page = list_entry(next, struct page, lru);
723 return page_address(page);
726 static inline struct trace_entry *
727 tracing_get_trace_entry(struct trace_array *tr, struct trace_array_cpu *data)
729 unsigned long idx, idx_next;
730 struct trace_entry *entry;
733 idx = data->trace_head_idx;
736 BUG_ON(idx * TRACE_ENTRY_SIZE >= PAGE_SIZE);
738 entry = data->trace_head + idx * TRACE_ENTRY_SIZE;
740 if (unlikely(idx_next >= ENTRIES_PER_PAGE)) {
741 data->trace_head = trace_next_page(data, data->trace_head);
745 if (data->trace_head == data->trace_tail &&
746 idx_next == data->trace_tail_idx) {
748 data->trace_tail_idx++;
749 if (data->trace_tail_idx >= ENTRIES_PER_PAGE) {
751 trace_next_page(data, data->trace_tail);
752 data->trace_tail_idx = 0;
756 data->trace_head_idx = idx_next;
762 tracing_generic_entry_update(struct trace_entry *entry, unsigned long flags)
764 struct task_struct *tsk = current;
767 pc = preempt_count();
769 entry->preempt_count = pc & 0xff;
770 entry->pid = (tsk) ? tsk->pid : 0;
771 entry->t = ftrace_now(raw_smp_processor_id());
772 entry->flags = (irqs_disabled_flags(flags) ? TRACE_FLAG_IRQS_OFF : 0) |
773 ((pc & HARDIRQ_MASK) ? TRACE_FLAG_HARDIRQ : 0) |
774 ((pc & SOFTIRQ_MASK) ? TRACE_FLAG_SOFTIRQ : 0) |
775 (need_resched() ? TRACE_FLAG_NEED_RESCHED : 0);
779 trace_function(struct trace_array *tr, struct trace_array_cpu *data,
780 unsigned long ip, unsigned long parent_ip, unsigned long flags)
782 struct trace_entry *entry;
783 unsigned long irq_flags;
785 raw_local_irq_save(irq_flags);
786 __raw_spin_lock(&data->lock);
787 entry = tracing_get_trace_entry(tr, data);
788 tracing_generic_entry_update(entry, flags);
789 entry->type = TRACE_FN;
791 entry->fn.parent_ip = parent_ip;
792 __raw_spin_unlock(&data->lock);
793 raw_local_irq_restore(irq_flags);
797 ftrace(struct trace_array *tr, struct trace_array_cpu *data,
798 unsigned long ip, unsigned long parent_ip, unsigned long flags)
800 if (likely(!atomic_read(&data->disabled)))
801 trace_function(tr, data, ip, parent_ip, flags);
805 __trace_special(void *__tr, void *__data,
806 unsigned long arg1, unsigned long arg2, unsigned long arg3)
808 struct trace_array_cpu *data = __data;
809 struct trace_array *tr = __tr;
810 struct trace_entry *entry;
811 unsigned long irq_flags;
813 raw_local_irq_save(irq_flags);
814 __raw_spin_lock(&data->lock);
815 entry = tracing_get_trace_entry(tr, data);
816 tracing_generic_entry_update(entry, 0);
817 entry->type = TRACE_SPECIAL;
818 entry->special.arg1 = arg1;
819 entry->special.arg2 = arg2;
820 entry->special.arg3 = arg3;
821 __raw_spin_unlock(&data->lock);
822 raw_local_irq_restore(irq_flags);
827 void __trace_stack(struct trace_array *tr,
828 struct trace_array_cpu *data,
832 struct trace_entry *entry;
833 struct stack_trace trace;
835 if (!(trace_flags & TRACE_ITER_STACKTRACE))
838 entry = tracing_get_trace_entry(tr, data);
839 tracing_generic_entry_update(entry, flags);
840 entry->type = TRACE_STACK;
842 memset(&entry->stack, 0, sizeof(entry->stack));
844 trace.nr_entries = 0;
845 trace.max_entries = FTRACE_STACK_ENTRIES;
847 trace.entries = entry->stack.caller;
849 save_stack_trace(&trace);
853 tracing_sched_switch_trace(struct trace_array *tr,
854 struct trace_array_cpu *data,
855 struct task_struct *prev,
856 struct task_struct *next,
859 struct trace_entry *entry;
860 unsigned long irq_flags;
862 raw_local_irq_save(irq_flags);
863 __raw_spin_lock(&data->lock);
864 entry = tracing_get_trace_entry(tr, data);
865 tracing_generic_entry_update(entry, flags);
866 entry->type = TRACE_CTX;
867 entry->ctx.prev_pid = prev->pid;
868 entry->ctx.prev_prio = prev->prio;
869 entry->ctx.prev_state = prev->state;
870 entry->ctx.next_pid = next->pid;
871 entry->ctx.next_prio = next->prio;
872 entry->ctx.next_state = next->state;
873 __trace_stack(tr, data, flags, 4);
874 __raw_spin_unlock(&data->lock);
875 raw_local_irq_restore(irq_flags);
879 tracing_sched_wakeup_trace(struct trace_array *tr,
880 struct trace_array_cpu *data,
881 struct task_struct *wakee,
882 struct task_struct *curr,
885 struct trace_entry *entry;
886 unsigned long irq_flags;
888 raw_local_irq_save(irq_flags);
889 __raw_spin_lock(&data->lock);
890 entry = tracing_get_trace_entry(tr, data);
891 tracing_generic_entry_update(entry, flags);
892 entry->type = TRACE_WAKE;
893 entry->ctx.prev_pid = curr->pid;
894 entry->ctx.prev_prio = curr->prio;
895 entry->ctx.prev_state = curr->state;
896 entry->ctx.next_pid = wakee->pid;
897 entry->ctx.next_prio = wakee->prio;
898 entry->ctx.next_state = wakee->state;
899 __trace_stack(tr, data, flags, 5);
900 __raw_spin_unlock(&data->lock);
901 raw_local_irq_restore(irq_flags);
908 function_trace_call(unsigned long ip, unsigned long parent_ip)
910 struct trace_array *tr = &global_trace;
911 struct trace_array_cpu *data;
916 if (unlikely(!tracer_enabled))
919 local_irq_save(flags);
920 cpu = raw_smp_processor_id();
921 data = tr->data[cpu];
922 disabled = atomic_inc_return(&data->disabled);
924 if (likely(disabled == 1))
925 trace_function(tr, data, ip, parent_ip, flags);
927 atomic_dec(&data->disabled);
928 local_irq_restore(flags);
931 static struct ftrace_ops trace_ops __read_mostly =
933 .func = function_trace_call,
936 void tracing_start_function_trace(void)
938 register_ftrace_function(&trace_ops);
941 void tracing_stop_function_trace(void)
943 unregister_ftrace_function(&trace_ops);
947 enum trace_file_type {
948 TRACE_FILE_LAT_FMT = 1,
951 static struct trace_entry *
952 trace_entry_idx(struct trace_array *tr, struct trace_array_cpu *data,
953 struct trace_iterator *iter, int cpu)
956 struct trace_entry *array;
958 if (iter->next_idx[cpu] >= tr->entries ||
959 iter->next_idx[cpu] >= data->trace_idx ||
960 (data->trace_head == data->trace_tail &&
961 data->trace_head_idx == data->trace_tail_idx))
964 if (!iter->next_page[cpu]) {
965 /* Initialize the iterator for this cpu trace buffer */
966 WARN_ON(!data->trace_tail);
967 page = virt_to_page(data->trace_tail);
968 iter->next_page[cpu] = &page->lru;
969 iter->next_page_idx[cpu] = data->trace_tail_idx;
972 page = list_entry(iter->next_page[cpu], struct page, lru);
973 BUG_ON(&data->trace_pages == &page->lru);
975 array = page_address(page);
977 WARN_ON(iter->next_page_idx[cpu] >= ENTRIES_PER_PAGE);
978 return &array[iter->next_page_idx[cpu]];
981 static struct trace_entry *
982 find_next_entry(struct trace_iterator *iter, int *ent_cpu)
984 struct trace_array *tr = iter->tr;
985 struct trace_entry *ent, *next = NULL;
989 for_each_tracing_cpu(cpu) {
990 if (!head_page(tr->data[cpu]))
992 ent = trace_entry_idx(tr, tr->data[cpu], iter, cpu);
994 * Pick the entry with the smallest timestamp:
996 if (ent && (!next || ent->t < next->t)) {
1003 *ent_cpu = next_cpu;
1008 static void trace_iterator_increment(struct trace_iterator *iter)
1011 iter->next_idx[iter->cpu]++;
1012 iter->next_page_idx[iter->cpu]++;
1014 if (iter->next_page_idx[iter->cpu] >= ENTRIES_PER_PAGE) {
1015 struct trace_array_cpu *data = iter->tr->data[iter->cpu];
1017 iter->next_page_idx[iter->cpu] = 0;
1018 iter->next_page[iter->cpu] =
1019 trace_next_list(data, iter->next_page[iter->cpu]);
1023 static void trace_consume(struct trace_iterator *iter)
1025 struct trace_array_cpu *data = iter->tr->data[iter->cpu];
1027 data->trace_tail_idx++;
1028 if (data->trace_tail_idx >= ENTRIES_PER_PAGE) {
1029 data->trace_tail = trace_next_page(data, data->trace_tail);
1030 data->trace_tail_idx = 0;
1033 /* Check if we empty it, then reset the index */
1034 if (data->trace_head == data->trace_tail &&
1035 data->trace_head_idx == data->trace_tail_idx)
1036 data->trace_idx = 0;
1039 static void *find_next_entry_inc(struct trace_iterator *iter)
1041 struct trace_entry *next;
1044 next = find_next_entry(iter, &next_cpu);
1046 iter->prev_ent = iter->ent;
1047 iter->prev_cpu = iter->cpu;
1050 iter->cpu = next_cpu;
1053 trace_iterator_increment(iter);
1055 return next ? iter : NULL;
1058 static void *s_next(struct seq_file *m, void *v, loff_t *pos)
1060 struct trace_iterator *iter = m->private;
1061 void *last_ent = iter->ent;
1067 /* can't go backwards */
1072 ent = find_next_entry_inc(iter);
1076 while (ent && iter->idx < i)
1077 ent = find_next_entry_inc(iter);
1081 if (last_ent && !ent)
1082 seq_puts(m, "\n\nvim:ft=help\n");
1087 static void *s_start(struct seq_file *m, loff_t *pos)
1089 struct trace_iterator *iter = m->private;
1094 mutex_lock(&trace_types_lock);
1096 if (!current_trace || current_trace != iter->trace) {
1097 mutex_unlock(&trace_types_lock);
1101 atomic_inc(&trace_record_cmdline_disabled);
1103 /* let the tracer grab locks here if needed */
1104 if (current_trace->start)
1105 current_trace->start(iter);
1107 if (*pos != iter->pos) {
1111 iter->prev_ent = NULL;
1112 iter->prev_cpu = -1;
1114 for_each_tracing_cpu(i) {
1115 iter->next_idx[i] = 0;
1116 iter->next_page[i] = NULL;
1119 for (p = iter; p && l < *pos; p = s_next(m, p, &l))
1124 p = s_next(m, p, &l);
1130 static void s_stop(struct seq_file *m, void *p)
1132 struct trace_iterator *iter = m->private;
1134 atomic_dec(&trace_record_cmdline_disabled);
1136 /* let the tracer release locks here if needed */
1137 if (current_trace && current_trace == iter->trace && iter->trace->stop)
1138 iter->trace->stop(iter);
1140 mutex_unlock(&trace_types_lock);
1144 seq_print_sym_short(struct trace_seq *s, const char *fmt, unsigned long address)
1146 #ifdef CONFIG_KALLSYMS
1147 char str[KSYM_SYMBOL_LEN];
1149 kallsyms_lookup(address, NULL, NULL, NULL, str);
1151 return trace_seq_printf(s, fmt, str);
1157 seq_print_sym_offset(struct trace_seq *s, const char *fmt,
1158 unsigned long address)
1160 #ifdef CONFIG_KALLSYMS
1161 char str[KSYM_SYMBOL_LEN];
1163 sprint_symbol(str, address);
1164 return trace_seq_printf(s, fmt, str);
1169 #ifndef CONFIG_64BIT
1170 # define IP_FMT "%08lx"
1172 # define IP_FMT "%016lx"
1176 seq_print_ip_sym(struct trace_seq *s, unsigned long ip, unsigned long sym_flags)
1181 return trace_seq_printf(s, "0");
1183 if (sym_flags & TRACE_ITER_SYM_OFFSET)
1184 ret = seq_print_sym_offset(s, "%s", ip);
1186 ret = seq_print_sym_short(s, "%s", ip);
1191 if (sym_flags & TRACE_ITER_SYM_ADDR)
1192 ret = trace_seq_printf(s, " <" IP_FMT ">", ip);
1196 static void print_lat_help_header(struct seq_file *m)
1198 seq_puts(m, "# _------=> CPU# \n");
1199 seq_puts(m, "# / _-----=> irqs-off \n");
1200 seq_puts(m, "# | / _----=> need-resched \n");
1201 seq_puts(m, "# || / _---=> hardirq/softirq \n");
1202 seq_puts(m, "# ||| / _--=> preempt-depth \n");
1203 seq_puts(m, "# |||| / \n");
1204 seq_puts(m, "# ||||| delay \n");
1205 seq_puts(m, "# cmd pid ||||| time | caller \n");
1206 seq_puts(m, "# \\ / ||||| \\ | / \n");
1209 static void print_func_help_header(struct seq_file *m)
1211 seq_puts(m, "# TASK-PID CPU# TIMESTAMP FUNCTION\n");
1212 seq_puts(m, "# | | | | |\n");
1217 print_trace_header(struct seq_file *m, struct trace_iterator *iter)
1219 unsigned long sym_flags = (trace_flags & TRACE_ITER_SYM_MASK);
1220 struct trace_array *tr = iter->tr;
1221 struct trace_array_cpu *data = tr->data[tr->cpu];
1222 struct tracer *type = current_trace;
1223 unsigned long total = 0;
1224 unsigned long entries = 0;
1226 const char *name = "preemption";
1231 for_each_tracing_cpu(cpu) {
1232 if (head_page(tr->data[cpu])) {
1233 total += tr->data[cpu]->trace_idx;
1234 if (tr->data[cpu]->trace_idx > tr->entries)
1235 entries += tr->entries;
1237 entries += tr->data[cpu]->trace_idx;
1241 seq_printf(m, "%s latency trace v1.1.5 on %s\n",
1243 seq_puts(m, "-----------------------------------"
1244 "---------------------------------\n");
1245 seq_printf(m, " latency: %lu us, #%lu/%lu, CPU#%d |"
1246 " (M:%s VP:%d, KP:%d, SP:%d HP:%d",
1247 nsecs_to_usecs(data->saved_latency),
1251 #if defined(CONFIG_PREEMPT_NONE)
1253 #elif defined(CONFIG_PREEMPT_VOLUNTARY)
1255 #elif defined(CONFIG_PREEMPT_DESKTOP)
1260 /* These are reserved for later use */
1263 seq_printf(m, " #P:%d)\n", num_online_cpus());
1267 seq_puts(m, " -----------------\n");
1268 seq_printf(m, " | task: %.16s-%d "
1269 "(uid:%d nice:%ld policy:%ld rt_prio:%ld)\n",
1270 data->comm, data->pid, data->uid, data->nice,
1271 data->policy, data->rt_priority);
1272 seq_puts(m, " -----------------\n");
1274 if (data->critical_start) {
1275 seq_puts(m, " => started at: ");
1276 seq_print_ip_sym(&iter->seq, data->critical_start, sym_flags);
1277 trace_print_seq(m, &iter->seq);
1278 seq_puts(m, "\n => ended at: ");
1279 seq_print_ip_sym(&iter->seq, data->critical_end, sym_flags);
1280 trace_print_seq(m, &iter->seq);
1288 lat_print_generic(struct trace_seq *s, struct trace_entry *entry, int cpu)
1290 int hardirq, softirq;
1293 comm = trace_find_cmdline(entry->pid);
1295 trace_seq_printf(s, "%8.8s-%-5d ", comm, entry->pid);
1296 trace_seq_printf(s, "%d", cpu);
1297 trace_seq_printf(s, "%c%c",
1298 (entry->flags & TRACE_FLAG_IRQS_OFF) ? 'd' : '.',
1299 ((entry->flags & TRACE_FLAG_NEED_RESCHED) ? 'N' : '.'));
1301 hardirq = entry->flags & TRACE_FLAG_HARDIRQ;
1302 softirq = entry->flags & TRACE_FLAG_SOFTIRQ;
1303 if (hardirq && softirq) {
1304 trace_seq_putc(s, 'H');
1307 trace_seq_putc(s, 'h');
1310 trace_seq_putc(s, 's');
1312 trace_seq_putc(s, '.');
1316 if (entry->preempt_count)
1317 trace_seq_printf(s, "%x", entry->preempt_count);
1319 trace_seq_puts(s, ".");
1322 unsigned long preempt_mark_thresh = 100;
1325 lat_print_timestamp(struct trace_seq *s, unsigned long long abs_usecs,
1326 unsigned long rel_usecs)
1328 trace_seq_printf(s, " %4lldus", abs_usecs);
1329 if (rel_usecs > preempt_mark_thresh)
1330 trace_seq_puts(s, "!: ");
1331 else if (rel_usecs > 1)
1332 trace_seq_puts(s, "+: ");
1334 trace_seq_puts(s, " : ");
1337 static const char state_to_char[] = TASK_STATE_TO_CHAR_STR;
1340 print_lat_fmt(struct trace_iterator *iter, unsigned int trace_idx, int cpu)
1342 struct trace_seq *s = &iter->seq;
1343 unsigned long sym_flags = (trace_flags & TRACE_ITER_SYM_MASK);
1344 struct trace_entry *next_entry = find_next_entry(iter, NULL);
1345 unsigned long verbose = (trace_flags & TRACE_ITER_VERBOSE);
1346 struct trace_entry *entry = iter->ent;
1347 unsigned long abs_usecs;
1348 unsigned long rel_usecs;
1356 rel_usecs = ns2usecs(next_entry->t - entry->t);
1357 abs_usecs = ns2usecs(entry->t - iter->tr->time_start);
1360 comm = trace_find_cmdline(entry->pid);
1361 trace_seq_printf(s, "%16s %5d %d %d %08x %08x [%08lx]"
1362 " %ld.%03ldms (+%ld.%03ldms): ",
1364 entry->pid, cpu, entry->flags,
1365 entry->preempt_count, trace_idx,
1368 abs_usecs % 1000, rel_usecs/1000,
1371 lat_print_generic(s, entry, cpu);
1372 lat_print_timestamp(s, abs_usecs, rel_usecs);
1374 switch (entry->type) {
1376 seq_print_ip_sym(s, entry->fn.ip, sym_flags);
1377 trace_seq_puts(s, " (");
1378 seq_print_ip_sym(s, entry->fn.parent_ip, sym_flags);
1379 trace_seq_puts(s, ")\n");
1383 T = entry->ctx.next_state < sizeof(state_to_char) ?
1384 state_to_char[entry->ctx.next_state] : 'X';
1386 state = entry->ctx.prev_state ? __ffs(entry->ctx.prev_state) + 1 : 0;
1387 S = state < sizeof(state_to_char) - 1 ? state_to_char[state] : 'X';
1388 comm = trace_find_cmdline(entry->ctx.next_pid);
1389 trace_seq_printf(s, " %5d:%3d:%c %s %5d:%3d:%c %s\n",
1390 entry->ctx.prev_pid,
1391 entry->ctx.prev_prio,
1392 S, entry->type == TRACE_CTX ? "==>" : " +",
1393 entry->ctx.next_pid,
1394 entry->ctx.next_prio,
1398 trace_seq_printf(s, "# %ld %ld %ld\n",
1399 entry->special.arg1,
1400 entry->special.arg2,
1401 entry->special.arg3);
1404 for (i = 0; i < FTRACE_STACK_ENTRIES; i++) {
1406 trace_seq_puts(s, " <= ");
1407 seq_print_ip_sym(s, entry->stack.caller[i], sym_flags);
1409 trace_seq_puts(s, "\n");
1412 trace_seq_printf(s, "Unknown type %d\n", entry->type);
1417 static int print_trace_fmt(struct trace_iterator *iter)
1419 struct trace_seq *s = &iter->seq;
1420 unsigned long sym_flags = (trace_flags & TRACE_ITER_SYM_MASK);
1421 struct trace_entry *entry;
1422 unsigned long usec_rem;
1423 unsigned long long t;
1432 comm = trace_find_cmdline(iter->ent->pid);
1434 t = ns2usecs(entry->t);
1435 usec_rem = do_div(t, 1000000ULL);
1436 secs = (unsigned long)t;
1438 ret = trace_seq_printf(s, "%16s-%-5d ", comm, entry->pid);
1441 ret = trace_seq_printf(s, "[%02d] ", iter->cpu);
1444 ret = trace_seq_printf(s, "%5lu.%06lu: ", secs, usec_rem);
1448 switch (entry->type) {
1450 ret = seq_print_ip_sym(s, entry->fn.ip, sym_flags);
1453 if ((sym_flags & TRACE_ITER_PRINT_PARENT) &&
1454 entry->fn.parent_ip) {
1455 ret = trace_seq_printf(s, " <-");
1458 ret = seq_print_ip_sym(s, entry->fn.parent_ip,
1463 ret = trace_seq_printf(s, "\n");
1469 S = entry->ctx.prev_state < sizeof(state_to_char) ?
1470 state_to_char[entry->ctx.prev_state] : 'X';
1471 T = entry->ctx.next_state < sizeof(state_to_char) ?
1472 state_to_char[entry->ctx.next_state] : 'X';
1473 ret = trace_seq_printf(s, " %5d:%3d:%c %s %5d:%3d:%c\n",
1474 entry->ctx.prev_pid,
1475 entry->ctx.prev_prio,
1477 entry->type == TRACE_CTX ? "==>" : " +",
1478 entry->ctx.next_pid,
1479 entry->ctx.next_prio,
1485 ret = trace_seq_printf(s, "# %ld %ld %ld\n",
1486 entry->special.arg1,
1487 entry->special.arg2,
1488 entry->special.arg3);
1493 for (i = 0; i < FTRACE_STACK_ENTRIES; i++) {
1495 ret = trace_seq_puts(s, " <= ");
1499 ret = seq_print_ip_sym(s, entry->stack.caller[i],
1504 ret = trace_seq_puts(s, "\n");
1512 static int print_raw_fmt(struct trace_iterator *iter)
1514 struct trace_seq *s = &iter->seq;
1515 struct trace_entry *entry;
1521 ret = trace_seq_printf(s, "%d %d %llu ",
1522 entry->pid, iter->cpu, entry->t);
1526 switch (entry->type) {
1528 ret = trace_seq_printf(s, "%x %x\n",
1529 entry->fn.ip, entry->fn.parent_ip);
1535 S = entry->ctx.prev_state < sizeof(state_to_char) ?
1536 state_to_char[entry->ctx.prev_state] : 'X';
1537 T = entry->ctx.next_state < sizeof(state_to_char) ?
1538 state_to_char[entry->ctx.next_state] : 'X';
1539 if (entry->type == TRACE_WAKE)
1541 ret = trace_seq_printf(s, "%d %d %c %d %d %c\n",
1542 entry->ctx.prev_pid,
1543 entry->ctx.prev_prio,
1545 entry->ctx.next_pid,
1546 entry->ctx.next_prio,
1553 ret = trace_seq_printf(s, "# %ld %ld %ld\n",
1554 entry->special.arg1,
1555 entry->special.arg2,
1556 entry->special.arg3);
1564 #define SEQ_PUT_FIELD_RET(s, x) \
1566 if (!trace_seq_putmem(s, &(x), sizeof(x))) \
1570 #define SEQ_PUT_HEX_FIELD_RET(s, x) \
1572 if (!trace_seq_putmem_hex(s, &(x), sizeof(x))) \
1576 static int print_hex_fmt(struct trace_iterator *iter)
1578 struct trace_seq *s = &iter->seq;
1579 unsigned char newline = '\n';
1580 struct trace_entry *entry;
1585 SEQ_PUT_HEX_FIELD_RET(s, entry->pid);
1586 SEQ_PUT_HEX_FIELD_RET(s, iter->cpu);
1587 SEQ_PUT_HEX_FIELD_RET(s, entry->t);
1589 switch (entry->type) {
1591 SEQ_PUT_HEX_FIELD_RET(s, entry->fn.ip);
1592 SEQ_PUT_HEX_FIELD_RET(s, entry->fn.parent_ip);
1596 S = entry->ctx.prev_state < sizeof(state_to_char) ?
1597 state_to_char[entry->ctx.prev_state] : 'X';
1598 T = entry->ctx.next_state < sizeof(state_to_char) ?
1599 state_to_char[entry->ctx.next_state] : 'X';
1600 if (entry->type == TRACE_WAKE)
1602 SEQ_PUT_HEX_FIELD_RET(s, entry->ctx.prev_pid);
1603 SEQ_PUT_HEX_FIELD_RET(s, entry->ctx.prev_prio);
1604 SEQ_PUT_HEX_FIELD_RET(s, S);
1605 SEQ_PUT_HEX_FIELD_RET(s, entry->ctx.next_pid);
1606 SEQ_PUT_HEX_FIELD_RET(s, entry->ctx.next_prio);
1607 SEQ_PUT_HEX_FIELD_RET(s, entry->fn.parent_ip);
1608 SEQ_PUT_HEX_FIELD_RET(s, T);
1612 SEQ_PUT_HEX_FIELD_RET(s, entry->special.arg1);
1613 SEQ_PUT_HEX_FIELD_RET(s, entry->special.arg2);
1614 SEQ_PUT_HEX_FIELD_RET(s, entry->special.arg3);
1617 SEQ_PUT_FIELD_RET(s, newline);
1622 static int print_bin_fmt(struct trace_iterator *iter)
1624 struct trace_seq *s = &iter->seq;
1625 struct trace_entry *entry;
1629 SEQ_PUT_FIELD_RET(s, entry->pid);
1630 SEQ_PUT_FIELD_RET(s, entry->cpu);
1631 SEQ_PUT_FIELD_RET(s, entry->t);
1633 switch (entry->type) {
1635 SEQ_PUT_FIELD_RET(s, entry->fn.ip);
1636 SEQ_PUT_FIELD_RET(s, entry->fn.parent_ip);
1639 SEQ_PUT_FIELD_RET(s, entry->ctx.prev_pid);
1640 SEQ_PUT_FIELD_RET(s, entry->ctx.prev_prio);
1641 SEQ_PUT_FIELD_RET(s, entry->ctx.prev_state);
1642 SEQ_PUT_FIELD_RET(s, entry->ctx.next_pid);
1643 SEQ_PUT_FIELD_RET(s, entry->ctx.next_prio);
1644 SEQ_PUT_FIELD_RET(s, entry->ctx.next_state);
1648 SEQ_PUT_FIELD_RET(s, entry->special.arg1);
1649 SEQ_PUT_FIELD_RET(s, entry->special.arg2);
1650 SEQ_PUT_FIELD_RET(s, entry->special.arg3);
1656 static int trace_empty(struct trace_iterator *iter)
1658 struct trace_array_cpu *data;
1661 for_each_tracing_cpu(cpu) {
1662 data = iter->tr->data[cpu];
1664 if (head_page(data) && data->trace_idx &&
1665 (data->trace_tail != data->trace_head ||
1666 data->trace_tail_idx != data->trace_head_idx))
1672 static int print_trace_line(struct trace_iterator *iter)
1674 if (iter->trace && iter->trace->print_line)
1675 return iter->trace->print_line(iter);
1677 if (trace_flags & TRACE_ITER_BIN)
1678 return print_bin_fmt(iter);
1680 if (trace_flags & TRACE_ITER_HEX)
1681 return print_hex_fmt(iter);
1683 if (trace_flags & TRACE_ITER_RAW)
1684 return print_raw_fmt(iter);
1686 if (iter->iter_flags & TRACE_FILE_LAT_FMT)
1687 return print_lat_fmt(iter, iter->idx, iter->cpu);
1689 return print_trace_fmt(iter);
1692 static int s_show(struct seq_file *m, void *v)
1694 struct trace_iterator *iter = v;
1696 if (iter->ent == NULL) {
1698 seq_printf(m, "# tracer: %s\n", iter->trace->name);
1701 if (iter->iter_flags & TRACE_FILE_LAT_FMT) {
1702 /* print nothing if the buffers are empty */
1703 if (trace_empty(iter))
1705 print_trace_header(m, iter);
1706 if (!(trace_flags & TRACE_ITER_VERBOSE))
1707 print_lat_help_header(m);
1709 if (!(trace_flags & TRACE_ITER_VERBOSE))
1710 print_func_help_header(m);
1713 print_trace_line(iter);
1714 trace_print_seq(m, &iter->seq);
1720 static struct seq_operations tracer_seq_ops = {
1727 static struct trace_iterator *
1728 __tracing_open(struct inode *inode, struct file *file, int *ret)
1730 struct trace_iterator *iter;
1732 if (tracing_disabled) {
1737 iter = kzalloc(sizeof(*iter), GFP_KERNEL);
1743 mutex_lock(&trace_types_lock);
1744 if (current_trace && current_trace->print_max)
1747 iter->tr = inode->i_private;
1748 iter->trace = current_trace;
1751 /* TODO stop tracer */
1752 *ret = seq_open(file, &tracer_seq_ops);
1754 struct seq_file *m = file->private_data;
1757 /* stop the trace while dumping */
1761 if (iter->trace && iter->trace->open)
1762 iter->trace->open(iter);
1767 mutex_unlock(&trace_types_lock);
1773 int tracing_open_generic(struct inode *inode, struct file *filp)
1775 if (tracing_disabled)
1778 filp->private_data = inode->i_private;
1782 int tracing_release(struct inode *inode, struct file *file)
1784 struct seq_file *m = (struct seq_file *)file->private_data;
1785 struct trace_iterator *iter = m->private;
1787 mutex_lock(&trace_types_lock);
1788 if (iter->trace && iter->trace->close)
1789 iter->trace->close(iter);
1791 /* reenable tracing if it was previously enabled */
1794 mutex_unlock(&trace_types_lock);
1796 seq_release(inode, file);
1801 static int tracing_open(struct inode *inode, struct file *file)
1805 __tracing_open(inode, file, &ret);
1810 static int tracing_lt_open(struct inode *inode, struct file *file)
1812 struct trace_iterator *iter;
1815 iter = __tracing_open(inode, file, &ret);
1818 iter->iter_flags |= TRACE_FILE_LAT_FMT;
1825 t_next(struct seq_file *m, void *v, loff_t *pos)
1827 struct tracer *t = m->private;
1839 static void *t_start(struct seq_file *m, loff_t *pos)
1841 struct tracer *t = m->private;
1844 mutex_lock(&trace_types_lock);
1845 for (; t && l < *pos; t = t_next(m, t, &l))
1851 static void t_stop(struct seq_file *m, void *p)
1853 mutex_unlock(&trace_types_lock);
1856 static int t_show(struct seq_file *m, void *v)
1858 struct tracer *t = v;
1863 seq_printf(m, "%s", t->name);
1872 static struct seq_operations show_traces_seq_ops = {
1879 static int show_traces_open(struct inode *inode, struct file *file)
1883 if (tracing_disabled)
1886 ret = seq_open(file, &show_traces_seq_ops);
1888 struct seq_file *m = file->private_data;
1889 m->private = trace_types;
1895 static struct file_operations tracing_fops = {
1896 .open = tracing_open,
1898 .llseek = seq_lseek,
1899 .release = tracing_release,
1902 static struct file_operations tracing_lt_fops = {
1903 .open = tracing_lt_open,
1905 .llseek = seq_lseek,
1906 .release = tracing_release,
1909 static struct file_operations show_traces_fops = {
1910 .open = show_traces_open,
1912 .release = seq_release,
1916 * Only trace on a CPU if the bitmask is set:
1918 static cpumask_t tracing_cpumask = CPU_MASK_ALL;
1921 * When tracing/tracing_cpu_mask is modified then this holds
1922 * the new bitmask we are about to install:
1924 static cpumask_t tracing_cpumask_new;
1927 * The tracer itself will not take this lock, but still we want
1928 * to provide a consistent cpumask to user-space:
1930 static DEFINE_MUTEX(tracing_cpumask_update_lock);
1933 * Temporary storage for the character representation of the
1934 * CPU bitmask (and one more byte for the newline):
1936 static char mask_str[NR_CPUS + 1];
1939 tracing_cpumask_read(struct file *filp, char __user *ubuf,
1940 size_t count, loff_t *ppos)
1944 mutex_lock(&tracing_cpumask_update_lock);
1946 len = cpumask_scnprintf(mask_str, count, tracing_cpumask);
1947 if (count - len < 2) {
1951 len += sprintf(mask_str + len, "\n");
1952 count = simple_read_from_buffer(ubuf, count, ppos, mask_str, NR_CPUS+1);
1955 mutex_unlock(&tracing_cpumask_update_lock);
1961 tracing_cpumask_write(struct file *filp, const char __user *ubuf,
1962 size_t count, loff_t *ppos)
1966 mutex_lock(&tracing_cpumask_update_lock);
1967 err = cpumask_parse_user(ubuf, count, tracing_cpumask_new);
1971 raw_local_irq_disable();
1972 __raw_spin_lock(&ftrace_max_lock);
1973 for_each_tracing_cpu(cpu) {
1975 * Increase/decrease the disabled counter if we are
1976 * about to flip a bit in the cpumask:
1978 if (cpu_isset(cpu, tracing_cpumask) &&
1979 !cpu_isset(cpu, tracing_cpumask_new)) {
1980 atomic_inc(&global_trace.data[cpu]->disabled);
1982 if (!cpu_isset(cpu, tracing_cpumask) &&
1983 cpu_isset(cpu, tracing_cpumask_new)) {
1984 atomic_dec(&global_trace.data[cpu]->disabled);
1987 __raw_spin_unlock(&ftrace_max_lock);
1988 raw_local_irq_enable();
1990 tracing_cpumask = tracing_cpumask_new;
1992 mutex_unlock(&tracing_cpumask_update_lock);
1997 mutex_unlock(&tracing_cpumask_update_lock);
2002 static struct file_operations tracing_cpumask_fops = {
2003 .open = tracing_open_generic,
2004 .read = tracing_cpumask_read,
2005 .write = tracing_cpumask_write,
2009 tracing_iter_ctrl_read(struct file *filp, char __user *ubuf,
2010 size_t cnt, loff_t *ppos)
2017 /* calulate max size */
2018 for (i = 0; trace_options[i]; i++) {
2019 len += strlen(trace_options[i]);
2020 len += 3; /* "no" and space */
2023 /* +2 for \n and \0 */
2024 buf = kmalloc(len + 2, GFP_KERNEL);
2028 for (i = 0; trace_options[i]; i++) {
2029 if (trace_flags & (1 << i))
2030 r += sprintf(buf + r, "%s ", trace_options[i]);
2032 r += sprintf(buf + r, "no%s ", trace_options[i]);
2035 r += sprintf(buf + r, "\n");
2036 WARN_ON(r >= len + 2);
2038 r = simple_read_from_buffer(ubuf, cnt, ppos, buf, r);
2046 tracing_iter_ctrl_write(struct file *filp, const char __user *ubuf,
2047 size_t cnt, loff_t *ppos)
2054 if (cnt >= sizeof(buf))
2057 if (copy_from_user(&buf, ubuf, cnt))
2062 if (strncmp(buf, "no", 2) == 0) {
2067 for (i = 0; trace_options[i]; i++) {
2068 int len = strlen(trace_options[i]);
2070 if (strncmp(cmp, trace_options[i], len) == 0) {
2072 trace_flags &= ~(1 << i);
2074 trace_flags |= (1 << i);
2079 * If no option could be set, return an error:
2081 if (!trace_options[i])
2089 static struct file_operations tracing_iter_fops = {
2090 .open = tracing_open_generic,
2091 .read = tracing_iter_ctrl_read,
2092 .write = tracing_iter_ctrl_write,
2095 static const char readme_msg[] =
2096 "tracing mini-HOWTO:\n\n"
2098 "# mount -t debugfs nodev /debug\n\n"
2099 "# cat /debug/tracing/available_tracers\n"
2100 "wakeup preemptirqsoff preemptoff irqsoff ftrace sched_switch none\n\n"
2101 "# cat /debug/tracing/current_tracer\n"
2103 "# echo sched_switch > /debug/tracing/current_tracer\n"
2104 "# cat /debug/tracing/current_tracer\n"
2106 "# cat /debug/tracing/iter_ctrl\n"
2107 "noprint-parent nosym-offset nosym-addr noverbose\n"
2108 "# echo print-parent > /debug/tracing/iter_ctrl\n"
2109 "# echo 1 > /debug/tracing/tracing_enabled\n"
2110 "# cat /debug/tracing/trace > /tmp/trace.txt\n"
2111 "echo 0 > /debug/tracing/tracing_enabled\n"
2115 tracing_readme_read(struct file *filp, char __user *ubuf,
2116 size_t cnt, loff_t *ppos)
2118 return simple_read_from_buffer(ubuf, cnt, ppos,
2119 readme_msg, strlen(readme_msg));
2122 static struct file_operations tracing_readme_fops = {
2123 .open = tracing_open_generic,
2124 .read = tracing_readme_read,
2128 tracing_ctrl_read(struct file *filp, char __user *ubuf,
2129 size_t cnt, loff_t *ppos)
2131 struct trace_array *tr = filp->private_data;
2135 r = sprintf(buf, "%ld\n", tr->ctrl);
2136 return simple_read_from_buffer(ubuf, cnt, ppos, buf, r);
2140 tracing_ctrl_write(struct file *filp, const char __user *ubuf,
2141 size_t cnt, loff_t *ppos)
2143 struct trace_array *tr = filp->private_data;
2148 if (cnt >= sizeof(buf))
2151 if (copy_from_user(&buf, ubuf, cnt))
2156 ret = strict_strtoul(buf, 10, &val);
2162 mutex_lock(&trace_types_lock);
2163 if (tr->ctrl ^ val) {
2171 if (current_trace && current_trace->ctrl_update)
2172 current_trace->ctrl_update(tr);
2174 mutex_unlock(&trace_types_lock);
2182 tracing_set_trace_read(struct file *filp, char __user *ubuf,
2183 size_t cnt, loff_t *ppos)
2185 char buf[max_tracer_type_len+2];
2188 mutex_lock(&trace_types_lock);
2190 r = sprintf(buf, "%s\n", current_trace->name);
2192 r = sprintf(buf, "\n");
2193 mutex_unlock(&trace_types_lock);
2195 return simple_read_from_buffer(ubuf, cnt, ppos, buf, r);
2199 tracing_set_trace_write(struct file *filp, const char __user *ubuf,
2200 size_t cnt, loff_t *ppos)
2202 struct trace_array *tr = &global_trace;
2204 char buf[max_tracer_type_len+1];
2207 if (cnt > max_tracer_type_len)
2208 cnt = max_tracer_type_len;
2210 if (copy_from_user(&buf, ubuf, cnt))
2215 /* strip ending whitespace. */
2216 for (i = cnt - 1; i > 0 && isspace(buf[i]); i--)
2219 mutex_lock(&trace_types_lock);
2220 for (t = trace_types; t; t = t->next) {
2221 if (strcmp(t->name, buf) == 0)
2224 if (!t || t == current_trace)
2227 if (current_trace && current_trace->reset)
2228 current_trace->reset(tr);
2235 mutex_unlock(&trace_types_lock);
2243 tracing_max_lat_read(struct file *filp, char __user *ubuf,
2244 size_t cnt, loff_t *ppos)
2246 unsigned long *ptr = filp->private_data;
2250 r = snprintf(buf, sizeof(buf), "%ld\n",
2251 *ptr == (unsigned long)-1 ? -1 : nsecs_to_usecs(*ptr));
2252 if (r > sizeof(buf))
2254 return simple_read_from_buffer(ubuf, cnt, ppos, buf, r);
2258 tracing_max_lat_write(struct file *filp, const char __user *ubuf,
2259 size_t cnt, loff_t *ppos)
2261 long *ptr = filp->private_data;
2266 if (cnt >= sizeof(buf))
2269 if (copy_from_user(&buf, ubuf, cnt))
2274 ret = strict_strtoul(buf, 10, &val);
2283 static atomic_t tracing_reader;
2285 static int tracing_open_pipe(struct inode *inode, struct file *filp)
2287 struct trace_iterator *iter;
2289 if (tracing_disabled)
2292 /* We only allow for reader of the pipe */
2293 if (atomic_inc_return(&tracing_reader) != 1) {
2294 atomic_dec(&tracing_reader);
2298 /* create a buffer to store the information to pass to userspace */
2299 iter = kzalloc(sizeof(*iter), GFP_KERNEL);
2303 iter->tr = &global_trace;
2304 iter->trace = current_trace;
2306 filp->private_data = iter;
2311 static int tracing_release_pipe(struct inode *inode, struct file *file)
2313 struct trace_iterator *iter = file->private_data;
2316 atomic_dec(&tracing_reader);
2322 tracing_poll_pipe(struct file *filp, poll_table *poll_table)
2324 struct trace_iterator *iter = filp->private_data;
2326 if (trace_flags & TRACE_ITER_BLOCK) {
2328 * Always select as readable when in blocking mode
2330 return POLLIN | POLLRDNORM;
2332 if (!trace_empty(iter))
2333 return POLLIN | POLLRDNORM;
2334 poll_wait(filp, &trace_wait, poll_table);
2335 if (!trace_empty(iter))
2336 return POLLIN | POLLRDNORM;
2346 tracing_read_pipe(struct file *filp, char __user *ubuf,
2347 size_t cnt, loff_t *ppos)
2349 struct trace_iterator *iter = filp->private_data;
2350 struct trace_array_cpu *data;
2351 struct trace_array *tr = iter->tr;
2352 struct tracer *tracer = iter->trace;
2353 static cpumask_t mask;
2355 unsigned long flags;
2356 #ifdef CONFIG_FTRACE
2364 /* return any leftover data */
2365 if (iter->seq.len > start) {
2366 len = iter->seq.len - start;
2369 ret = copy_to_user(ubuf, iter->seq.buffer + start, cnt);
2378 trace_seq_reset(&iter->seq);
2381 while (trace_empty(iter)) {
2383 if ((filp->f_flags & O_NONBLOCK))
2387 * This is a make-shift waitqueue. The reason we don't use
2388 * an actual wait queue is because:
2389 * 1) we only ever have one waiter
2390 * 2) the tracing, traces all functions, we don't want
2391 * the overhead of calling wake_up and friends
2392 * (and tracing them too)
2393 * Anyway, this is really very primitive wakeup.
2395 set_current_state(TASK_INTERRUPTIBLE);
2396 iter->tr->waiter = current;
2398 /* sleep for one second, and try again. */
2399 schedule_timeout(HZ);
2401 iter->tr->waiter = NULL;
2403 if (signal_pending(current))
2406 if (iter->trace != current_trace)
2410 * We block until we read something and tracing is disabled.
2411 * We still block if tracing is disabled, but we have never
2412 * read anything. This allows a user to cat this file, and
2413 * then enable tracing. But after we have read something,
2414 * we give an EOF when tracing is again disabled.
2416 * iter->pos will be 0 if we haven't read anything.
2418 if (!tracer_enabled && iter->pos)
2424 /* stop when tracing is finished */
2425 if (trace_empty(iter))
2428 if (cnt >= PAGE_SIZE)
2429 cnt = PAGE_SIZE - 1;
2431 memset(iter, 0, sizeof(*iter));
2433 iter->trace = tracer;
2437 * We need to stop all tracing on all CPUS to read the
2438 * the next buffer. This is a bit expensive, but is
2439 * not done often. We fill all what we can read,
2440 * and then release the locks again.
2444 local_irq_save(flags);
2445 #ifdef CONFIG_FTRACE
2446 ftrace_save = ftrace_enabled;
2450 for_each_tracing_cpu(cpu) {
2451 data = iter->tr->data[cpu];
2453 if (!head_page(data) || !data->trace_idx)
2456 atomic_inc(&data->disabled);
2460 for_each_cpu_mask(cpu, mask) {
2461 data = iter->tr->data[cpu];
2462 __raw_spin_lock(&data->lock);
2465 while (find_next_entry_inc(iter) != NULL) {
2466 int len = iter->seq.len;
2468 ret = print_trace_line(iter);
2470 /* don't print partial lines */
2471 iter->seq.len = len;
2475 trace_consume(iter);
2477 if (iter->seq.len >= cnt)
2481 for_each_cpu_mask(cpu, mask) {
2482 data = iter->tr->data[cpu];
2483 __raw_spin_unlock(&data->lock);
2486 for_each_cpu_mask(cpu, mask) {
2487 data = iter->tr->data[cpu];
2488 atomic_dec(&data->disabled);
2490 #ifdef CONFIG_FTRACE
2491 ftrace_enabled = ftrace_save;
2493 local_irq_restore(flags);
2495 /* Now copy what we have to the user */
2496 read = iter->seq.len;
2500 ret = copy_to_user(ubuf, iter->seq.buffer, read);
2502 if (read < iter->seq.len)
2505 trace_seq_reset(&iter->seq);
2514 tracing_entries_read(struct file *filp, char __user *ubuf,
2515 size_t cnt, loff_t *ppos)
2517 struct trace_array *tr = filp->private_data;
2521 r = sprintf(buf, "%lu\n", tr->entries);
2522 return simple_read_from_buffer(ubuf, cnt, ppos, buf, r);
2526 tracing_entries_write(struct file *filp, const char __user *ubuf,
2527 size_t cnt, loff_t *ppos)
2533 if (cnt >= sizeof(buf))
2536 if (copy_from_user(&buf, ubuf, cnt))
2541 ret = strict_strtoul(buf, 10, &val);
2545 /* must have at least 1 entry */
2549 mutex_lock(&trace_types_lock);
2551 if (current_trace != &no_tracer) {
2553 pr_info("ftrace: set current_tracer to none"
2554 " before modifying buffer size\n");
2558 if (val > global_trace.entries) {
2559 while (global_trace.entries < val) {
2560 if (trace_alloc_page()) {
2566 /* include the number of entries in val (inc of page entries) */
2567 while (global_trace.entries > val + (ENTRIES_PER_PAGE - 1))
2574 max_tr.entries = global_trace.entries;
2575 mutex_unlock(&trace_types_lock);
2580 static struct file_operations tracing_max_lat_fops = {
2581 .open = tracing_open_generic,
2582 .read = tracing_max_lat_read,
2583 .write = tracing_max_lat_write,
2586 static struct file_operations tracing_ctrl_fops = {
2587 .open = tracing_open_generic,
2588 .read = tracing_ctrl_read,
2589 .write = tracing_ctrl_write,
2592 static struct file_operations set_tracer_fops = {
2593 .open = tracing_open_generic,
2594 .read = tracing_set_trace_read,
2595 .write = tracing_set_trace_write,
2598 static struct file_operations tracing_pipe_fops = {
2599 .open = tracing_open_pipe,
2600 .poll = tracing_poll_pipe,
2601 .read = tracing_read_pipe,
2602 .release = tracing_release_pipe,
2605 static struct file_operations tracing_entries_fops = {
2606 .open = tracing_open_generic,
2607 .read = tracing_entries_read,
2608 .write = tracing_entries_write,
2611 #ifdef CONFIG_DYNAMIC_FTRACE
2614 tracing_read_long(struct file *filp, char __user *ubuf,
2615 size_t cnt, loff_t *ppos)
2617 unsigned long *p = filp->private_data;
2621 r = sprintf(buf, "%ld\n", *p);
2623 return simple_read_from_buffer(ubuf, cnt, ppos, buf, r);
2626 static struct file_operations tracing_read_long_fops = {
2627 .open = tracing_open_generic,
2628 .read = tracing_read_long,
2632 static struct dentry *d_tracer;
2634 struct dentry *tracing_init_dentry(void)
2641 d_tracer = debugfs_create_dir("tracing", NULL);
2643 if (!d_tracer && !once) {
2645 pr_warning("Could not create debugfs directory 'tracing'\n");
2652 #ifdef CONFIG_FTRACE_SELFTEST
2653 /* Let selftest have access to static functions in this file */
2654 #include "trace_selftest.c"
2657 static __init void tracer_init_debugfs(void)
2659 struct dentry *d_tracer;
2660 struct dentry *entry;
2662 d_tracer = tracing_init_dentry();
2664 entry = debugfs_create_file("tracing_enabled", 0644, d_tracer,
2665 &global_trace, &tracing_ctrl_fops);
2667 pr_warning("Could not create debugfs 'tracing_enabled' entry\n");
2669 entry = debugfs_create_file("iter_ctrl", 0644, d_tracer,
2670 NULL, &tracing_iter_fops);
2672 pr_warning("Could not create debugfs 'iter_ctrl' entry\n");
2674 entry = debugfs_create_file("tracing_cpumask", 0644, d_tracer,
2675 NULL, &tracing_cpumask_fops);
2677 pr_warning("Could not create debugfs 'tracing_cpumask' entry\n");
2679 entry = debugfs_create_file("latency_trace", 0444, d_tracer,
2680 &global_trace, &tracing_lt_fops);
2682 pr_warning("Could not create debugfs 'latency_trace' entry\n");
2684 entry = debugfs_create_file("trace", 0444, d_tracer,
2685 &global_trace, &tracing_fops);
2687 pr_warning("Could not create debugfs 'trace' entry\n");
2689 entry = debugfs_create_file("available_tracers", 0444, d_tracer,
2690 &global_trace, &show_traces_fops);
2692 pr_warning("Could not create debugfs 'trace' entry\n");
2694 entry = debugfs_create_file("current_tracer", 0444, d_tracer,
2695 &global_trace, &set_tracer_fops);
2697 pr_warning("Could not create debugfs 'trace' entry\n");
2699 entry = debugfs_create_file("tracing_max_latency", 0644, d_tracer,
2700 &tracing_max_latency,
2701 &tracing_max_lat_fops);
2703 pr_warning("Could not create debugfs "
2704 "'tracing_max_latency' entry\n");
2706 entry = debugfs_create_file("tracing_thresh", 0644, d_tracer,
2707 &tracing_thresh, &tracing_max_lat_fops);
2709 pr_warning("Could not create debugfs "
2710 "'tracing_threash' entry\n");
2711 entry = debugfs_create_file("README", 0644, d_tracer,
2712 NULL, &tracing_readme_fops);
2714 pr_warning("Could not create debugfs 'README' entry\n");
2716 entry = debugfs_create_file("trace_pipe", 0644, d_tracer,
2717 NULL, &tracing_pipe_fops);
2719 pr_warning("Could not create debugfs "
2720 "'tracing_threash' entry\n");
2722 entry = debugfs_create_file("trace_entries", 0644, d_tracer,
2723 &global_trace, &tracing_entries_fops);
2725 pr_warning("Could not create debugfs "
2726 "'tracing_threash' entry\n");
2728 #ifdef CONFIG_DYNAMIC_FTRACE
2729 entry = debugfs_create_file("dyn_ftrace_total_info", 0444, d_tracer,
2730 &ftrace_update_tot_cnt,
2731 &tracing_read_long_fops);
2733 pr_warning("Could not create debugfs "
2734 "'dyn_ftrace_total_info' entry\n");
2738 static int trace_alloc_page(void)
2740 struct trace_array_cpu *data;
2741 struct page *page, *tmp;
2746 /* first allocate a page for each CPU */
2747 for_each_tracing_cpu(i) {
2748 array = (void *)__get_free_page(GFP_KERNEL);
2749 if (array == NULL) {
2750 printk(KERN_ERR "tracer: failed to allocate page"
2751 "for trace buffer!\n");
2755 page = virt_to_page(array);
2756 list_add(&page->lru, &pages);
2758 /* Only allocate if we are actually using the max trace */
2759 #ifdef CONFIG_TRACER_MAX_TRACE
2760 array = (void *)__get_free_page(GFP_KERNEL);
2761 if (array == NULL) {
2762 printk(KERN_ERR "tracer: failed to allocate page"
2763 "for trace buffer!\n");
2766 page = virt_to_page(array);
2767 list_add(&page->lru, &pages);
2771 /* Now that we successfully allocate a page per CPU, add them */
2772 for_each_tracing_cpu(i) {
2773 data = global_trace.data[i];
2774 page = list_entry(pages.next, struct page, lru);
2775 list_del_init(&page->lru);
2776 list_add_tail(&page->lru, &data->trace_pages);
2779 #ifdef CONFIG_TRACER_MAX_TRACE
2780 data = max_tr.data[i];
2781 page = list_entry(pages.next, struct page, lru);
2782 list_del_init(&page->lru);
2783 list_add_tail(&page->lru, &data->trace_pages);
2787 global_trace.entries += ENTRIES_PER_PAGE;
2792 list_for_each_entry_safe(page, tmp, &pages, lru) {
2793 list_del_init(&page->lru);
2799 static int trace_free_page(void)
2801 struct trace_array_cpu *data;
2803 struct list_head *p;
2807 /* free one page from each buffer */
2808 for_each_tracing_cpu(i) {
2809 data = global_trace.data[i];
2810 p = data->trace_pages.next;
2811 if (p == &data->trace_pages) {
2812 /* should never happen */
2814 tracing_disabled = 1;
2818 page = list_entry(p, struct page, lru);
2820 list_del(&page->lru);
2823 tracing_reset(data);
2825 #ifdef CONFIG_TRACER_MAX_TRACE
2826 data = max_tr.data[i];
2827 p = data->trace_pages.next;
2828 if (p == &data->trace_pages) {
2829 /* should never happen */
2831 tracing_disabled = 1;
2835 page = list_entry(p, struct page, lru);
2837 list_del(&page->lru);
2840 tracing_reset(data);
2843 global_trace.entries -= ENTRIES_PER_PAGE;
2848 __init static int tracer_alloc_buffers(void)
2850 struct trace_array_cpu *data;
2857 global_trace.ctrl = tracer_enabled;
2859 /* TODO: make the number of buffers hot pluggable with CPUS */
2860 tracing_nr_buffers = num_possible_cpus();
2861 tracing_buffer_mask = cpu_possible_map;
2863 /* Allocate the first page for all buffers */
2864 for_each_tracing_cpu(i) {
2865 data = global_trace.data[i] = &per_cpu(global_trace_cpu, i);
2866 max_tr.data[i] = &per_cpu(max_data, i);
2868 array = (void *)__get_free_page(GFP_KERNEL);
2869 if (array == NULL) {
2870 printk(KERN_ERR "tracer: failed to allocate page"
2871 "for trace buffer!\n");
2875 /* set the array to the list */
2876 INIT_LIST_HEAD(&data->trace_pages);
2877 page = virt_to_page(array);
2878 list_add(&page->lru, &data->trace_pages);
2879 /* use the LRU flag to differentiate the two buffers */
2882 data->lock = (raw_spinlock_t)__RAW_SPIN_LOCK_UNLOCKED;
2883 max_tr.data[i]->lock = (raw_spinlock_t)__RAW_SPIN_LOCK_UNLOCKED;
2885 /* Only allocate if we are actually using the max trace */
2886 #ifdef CONFIG_TRACER_MAX_TRACE
2887 array = (void *)__get_free_page(GFP_KERNEL);
2888 if (array == NULL) {
2889 printk(KERN_ERR "tracer: failed to allocate page"
2890 "for trace buffer!\n");
2894 INIT_LIST_HEAD(&max_tr.data[i]->trace_pages);
2895 page = virt_to_page(array);
2896 list_add(&page->lru, &max_tr.data[i]->trace_pages);
2902 * Since we allocate by orders of pages, we may be able to
2905 global_trace.entries = ENTRIES_PER_PAGE;
2908 while (global_trace.entries < trace_nr_entries) {
2909 if (trace_alloc_page())
2913 max_tr.entries = global_trace.entries;
2915 pr_info("tracer: %d pages allocated for %ld",
2916 pages, trace_nr_entries);
2917 pr_info(" entries of %ld bytes\n", (long)TRACE_ENTRY_SIZE);
2918 pr_info(" actual entries %ld\n", global_trace.entries);
2920 tracer_init_debugfs();
2922 trace_init_cmdlines();
2924 register_tracer(&no_tracer);
2925 current_trace = &no_tracer;
2927 /* All seems OK, enable tracing */
2928 tracing_disabled = 0;
2933 for (i-- ; i >= 0; i--) {
2934 struct page *page, *tmp;
2935 struct trace_array_cpu *data = global_trace.data[i];
2938 list_for_each_entry_safe(page, tmp,
2939 &data->trace_pages, lru) {
2940 list_del_init(&page->lru);
2945 #ifdef CONFIG_TRACER_MAX_TRACE
2946 data = max_tr.data[i];
2948 list_for_each_entry_safe(page, tmp,
2949 &data->trace_pages, lru) {
2950 list_del_init(&page->lru);
2958 fs_initcall(tracer_alloc_buffers);