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/ring_buffer.h>
15 #include <generated/utsrelease.h>
16 #include <linux/stacktrace.h>
17 #include <linux/writeback.h>
18 #include <linux/kallsyms.h>
19 #include <linux/seq_file.h>
20 #include <linux/notifier.h>
21 #include <linux/irqflags.h>
22 #include <linux/debugfs.h>
23 #include <linux/pagemap.h>
24 #include <linux/hardirq.h>
25 #include <linux/linkage.h>
26 #include <linux/uaccess.h>
27 #include <linux/kprobes.h>
28 #include <linux/ftrace.h>
29 #include <linux/module.h>
30 #include <linux/percpu.h>
31 #include <linux/splice.h>
32 #include <linux/kdebug.h>
33 #include <linux/string.h>
34 #include <linux/rwsem.h>
35 #include <linux/slab.h>
36 #include <linux/ctype.h>
37 #include <linux/init.h>
38 #include <linux/poll.h>
42 #include "trace_output.h"
45 * On boot up, the ring buffer is set to the minimum size, so that
46 * we do not waste memory on systems that are not using tracing.
48 int ring_buffer_expanded;
51 * We need to change this state when a selftest is running.
52 * A selftest will lurk into the ring-buffer to count the
53 * entries inserted during the selftest although some concurrent
54 * insertions into the ring-buffer such as trace_printk could occurred
55 * at the same time, giving false positive or negative results.
57 static bool __read_mostly tracing_selftest_running;
60 * If a tracer is running, we do not want to run SELFTEST.
62 bool __read_mostly tracing_selftest_disabled;
64 /* For tracers that don't implement custom flags */
65 static struct tracer_opt dummy_tracer_opt[] = {
69 static struct tracer_flags dummy_tracer_flags = {
71 .opts = dummy_tracer_opt
74 static int dummy_set_flag(u32 old_flags, u32 bit, int set)
80 * Kill all tracing for good (never come back).
81 * It is initialized to 1 but will turn to zero if the initialization
82 * of the tracer is successful. But that is the only place that sets
85 static int tracing_disabled = 1;
87 DEFINE_PER_CPU(int, ftrace_cpu_disabled);
89 static inline void ftrace_disable_cpu(void)
92 __this_cpu_inc(ftrace_cpu_disabled);
95 static inline void ftrace_enable_cpu(void)
97 __this_cpu_dec(ftrace_cpu_disabled);
101 cpumask_var_t __read_mostly tracing_buffer_mask;
104 * ftrace_dump_on_oops - variable to dump ftrace buffer on oops
106 * If there is an oops (or kernel panic) and the ftrace_dump_on_oops
107 * is set, then ftrace_dump is called. This will output the contents
108 * of the ftrace buffers to the console. This is very useful for
109 * capturing traces that lead to crashes and outputing it to a
112 * It is default off, but you can enable it with either specifying
113 * "ftrace_dump_on_oops" in the kernel command line, or setting
114 * /proc/sys/kernel/ftrace_dump_on_oops
115 * Set 1 if you want to dump buffers of all CPUs
116 * Set 2 if you want to dump the buffer of the CPU that triggered oops
119 enum ftrace_dump_mode ftrace_dump_on_oops;
121 static int tracing_set_tracer(const char *buf);
123 #define MAX_TRACER_SIZE 100
124 static char bootup_tracer_buf[MAX_TRACER_SIZE] __initdata;
125 static char *default_bootup_tracer;
127 static int __init set_cmdline_ftrace(char *str)
129 strncpy(bootup_tracer_buf, str, MAX_TRACER_SIZE);
130 default_bootup_tracer = bootup_tracer_buf;
131 /* We are using ftrace early, expand it */
132 ring_buffer_expanded = 1;
135 __setup("ftrace=", set_cmdline_ftrace);
137 static int __init set_ftrace_dump_on_oops(char *str)
139 if (*str++ != '=' || !*str) {
140 ftrace_dump_on_oops = DUMP_ALL;
144 if (!strcmp("orig_cpu", str)) {
145 ftrace_dump_on_oops = DUMP_ORIG;
151 __setup("ftrace_dump_on_oops", set_ftrace_dump_on_oops);
153 unsigned long long ns2usecs(cycle_t nsec)
161 * The global_trace is the descriptor that holds the tracing
162 * buffers for the live tracing. For each CPU, it contains
163 * a link list of pages that will store trace entries. The
164 * page descriptor of the pages in the memory is used to hold
165 * the link list by linking the lru item in the page descriptor
166 * to each of the pages in the buffer per CPU.
168 * For each active CPU there is a data field that holds the
169 * pages for the buffer for that CPU. Each CPU has the same number
170 * of pages allocated for its buffer.
172 static struct trace_array global_trace;
174 static DEFINE_PER_CPU(struct trace_array_cpu, global_trace_cpu);
176 int filter_current_check_discard(struct ring_buffer *buffer,
177 struct ftrace_event_call *call, void *rec,
178 struct ring_buffer_event *event)
180 return filter_check_discard(call, rec, buffer, event);
182 EXPORT_SYMBOL_GPL(filter_current_check_discard);
184 cycle_t ftrace_now(int cpu)
188 /* Early boot up does not have a buffer yet */
189 if (!global_trace.buffer)
190 return trace_clock_local();
192 ts = ring_buffer_time_stamp(global_trace.buffer, cpu);
193 ring_buffer_normalize_time_stamp(global_trace.buffer, cpu, &ts);
199 * The max_tr is used to snapshot the global_trace when a maximum
200 * latency is reached. Some tracers will use this to store a maximum
201 * trace while it continues examining live traces.
203 * The buffers for the max_tr are set up the same as the global_trace.
204 * When a snapshot is taken, the link list of the max_tr is swapped
205 * with the link list of the global_trace and the buffers are reset for
206 * the global_trace so the tracing can continue.
208 static struct trace_array max_tr;
210 static DEFINE_PER_CPU(struct trace_array_cpu, max_tr_data);
212 /* tracer_enabled is used to toggle activation of a tracer */
213 static int tracer_enabled = 1;
216 * tracing_is_enabled - return tracer_enabled status
218 * This function is used by other tracers to know the status
219 * of the tracer_enabled flag. Tracers may use this function
220 * to know if it should enable their features when starting
221 * up. See irqsoff tracer for an example (start_irqsoff_tracer).
223 int tracing_is_enabled(void)
225 return tracer_enabled;
229 * trace_buf_size is the size in bytes that is allocated
230 * for a buffer. Note, the number of bytes is always rounded
233 * This number is purposely set to a low number of 16384.
234 * If the dump on oops happens, it will be much appreciated
235 * to not have to wait for all that output. Anyway this can be
236 * boot time and run time configurable.
238 #define TRACE_BUF_SIZE_DEFAULT 1441792UL /* 16384 * 88 (sizeof(entry)) */
240 static unsigned long trace_buf_size = TRACE_BUF_SIZE_DEFAULT;
242 /* trace_types holds a link list of available tracers. */
243 static struct tracer *trace_types __read_mostly;
245 /* current_trace points to the tracer that is currently active */
246 static struct tracer *current_trace __read_mostly;
249 * trace_types_lock is used to protect the trace_types list.
251 static DEFINE_MUTEX(trace_types_lock);
254 * serialize the access of the ring buffer
256 * ring buffer serializes readers, but it is low level protection.
257 * The validity of the events (which returns by ring_buffer_peek() ..etc)
258 * are not protected by ring buffer.
260 * The content of events may become garbage if we allow other process consumes
261 * these events concurrently:
262 * A) the page of the consumed events may become a normal page
263 * (not reader page) in ring buffer, and this page will be rewrited
264 * by events producer.
265 * B) The page of the consumed events may become a page for splice_read,
266 * and this page will be returned to system.
268 * These primitives allow multi process access to different cpu ring buffer
271 * These primitives don't distinguish read-only and read-consume access.
272 * Multi read-only access are also serialized.
276 static DECLARE_RWSEM(all_cpu_access_lock);
277 static DEFINE_PER_CPU(struct mutex, cpu_access_lock);
279 static inline void trace_access_lock(int cpu)
281 if (cpu == TRACE_PIPE_ALL_CPU) {
282 /* gain it for accessing the whole ring buffer. */
283 down_write(&all_cpu_access_lock);
285 /* gain it for accessing a cpu ring buffer. */
287 /* Firstly block other trace_access_lock(TRACE_PIPE_ALL_CPU). */
288 down_read(&all_cpu_access_lock);
290 /* Secondly block other access to this @cpu ring buffer. */
291 mutex_lock(&per_cpu(cpu_access_lock, cpu));
295 static inline void trace_access_unlock(int cpu)
297 if (cpu == TRACE_PIPE_ALL_CPU) {
298 up_write(&all_cpu_access_lock);
300 mutex_unlock(&per_cpu(cpu_access_lock, cpu));
301 up_read(&all_cpu_access_lock);
305 static inline void trace_access_lock_init(void)
309 for_each_possible_cpu(cpu)
310 mutex_init(&per_cpu(cpu_access_lock, cpu));
315 static DEFINE_MUTEX(access_lock);
317 static inline void trace_access_lock(int cpu)
320 mutex_lock(&access_lock);
323 static inline void trace_access_unlock(int cpu)
326 mutex_unlock(&access_lock);
329 static inline void trace_access_lock_init(void)
335 /* trace_wait is a waitqueue for tasks blocked on trace_poll */
336 static DECLARE_WAIT_QUEUE_HEAD(trace_wait);
338 /* trace_flags holds trace_options default values */
339 unsigned long trace_flags = TRACE_ITER_PRINT_PARENT | TRACE_ITER_PRINTK |
340 TRACE_ITER_ANNOTATE | TRACE_ITER_CONTEXT_INFO | TRACE_ITER_SLEEP_TIME |
341 TRACE_ITER_GRAPH_TIME | TRACE_ITER_RECORD_CMD | TRACE_ITER_OVERWRITE |
344 static int trace_stop_count;
345 static DEFINE_RAW_SPINLOCK(tracing_start_lock);
347 static void wakeup_work_handler(struct work_struct *work)
349 wake_up(&trace_wait);
352 static DECLARE_DELAYED_WORK(wakeup_work, wakeup_work_handler);
355 * trace_wake_up - wake up tasks waiting for trace input
357 * Schedules a delayed work to wake up any task that is blocked on the
358 * trace_wait queue. These is used with trace_poll for tasks polling the
361 void trace_wake_up(void)
363 const unsigned long delay = msecs_to_jiffies(2);
365 if (trace_flags & TRACE_ITER_BLOCK)
367 schedule_delayed_work(&wakeup_work, delay);
370 static int __init set_buf_size(char *str)
372 unsigned long buf_size;
376 buf_size = memparse(str, &str);
377 /* nr_entries can not be zero */
380 trace_buf_size = buf_size;
383 __setup("trace_buf_size=", set_buf_size);
385 static int __init set_tracing_thresh(char *str)
387 unsigned long threshhold;
392 ret = strict_strtoul(str, 0, &threshhold);
395 tracing_thresh = threshhold * 1000;
398 __setup("tracing_thresh=", set_tracing_thresh);
400 unsigned long nsecs_to_usecs(unsigned long nsecs)
405 /* These must match the bit postions in trace_iterator_flags */
406 static const char *trace_options[] = {
438 { trace_clock_local, "local" },
439 { trace_clock_global, "global" },
440 { trace_clock_counter, "counter" },
446 * trace_parser_get_init - gets the buffer for trace parser
448 int trace_parser_get_init(struct trace_parser *parser, int size)
450 memset(parser, 0, sizeof(*parser));
452 parser->buffer = kmalloc(size, GFP_KERNEL);
461 * trace_parser_put - frees the buffer for trace parser
463 void trace_parser_put(struct trace_parser *parser)
465 kfree(parser->buffer);
469 * trace_get_user - reads the user input string separated by space
470 * (matched by isspace(ch))
472 * For each string found the 'struct trace_parser' is updated,
473 * and the function returns.
475 * Returns number of bytes read.
477 * See kernel/trace/trace.h for 'struct trace_parser' details.
479 int trace_get_user(struct trace_parser *parser, const char __user *ubuf,
480 size_t cnt, loff_t *ppos)
487 trace_parser_clear(parser);
489 ret = get_user(ch, ubuf++);
497 * The parser is not finished with the last write,
498 * continue reading the user input without skipping spaces.
501 /* skip white space */
502 while (cnt && isspace(ch)) {
503 ret = get_user(ch, ubuf++);
510 /* only spaces were written */
520 /* read the non-space input */
521 while (cnt && !isspace(ch)) {
522 if (parser->idx < parser->size - 1)
523 parser->buffer[parser->idx++] = ch;
528 ret = get_user(ch, ubuf++);
535 /* We either got finished input or we have to wait for another call. */
537 parser->buffer[parser->idx] = 0;
538 parser->cont = false;
541 parser->buffer[parser->idx++] = ch;
551 ssize_t trace_seq_to_user(struct trace_seq *s, char __user *ubuf, size_t cnt)
559 if (s->len <= s->readpos)
562 len = s->len - s->readpos;
565 ret = copy_to_user(ubuf, s->buffer + s->readpos, cnt);
575 static ssize_t trace_seq_to_buffer(struct trace_seq *s, void *buf, size_t cnt)
580 if (s->len <= s->readpos)
583 len = s->len - s->readpos;
586 ret = memcpy(buf, s->buffer + s->readpos, cnt);
595 * ftrace_max_lock is used to protect the swapping of buffers
596 * when taking a max snapshot. The buffers themselves are
597 * protected by per_cpu spinlocks. But the action of the swap
598 * needs its own lock.
600 * This is defined as a arch_spinlock_t in order to help
601 * with performance when lockdep debugging is enabled.
603 * It is also used in other places outside the update_max_tr
604 * so it needs to be defined outside of the
605 * CONFIG_TRACER_MAX_TRACE.
607 static arch_spinlock_t ftrace_max_lock =
608 (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
610 unsigned long __read_mostly tracing_thresh;
612 #ifdef CONFIG_TRACER_MAX_TRACE
613 unsigned long __read_mostly tracing_max_latency;
616 * Copy the new maximum trace into the separate maximum-trace
617 * structure. (this way the maximum trace is permanently saved,
618 * for later retrieval via /sys/kernel/debug/tracing/latency_trace)
621 __update_max_tr(struct trace_array *tr, struct task_struct *tsk, int cpu)
623 struct trace_array_cpu *data = tr->data[cpu];
624 struct trace_array_cpu *max_data;
627 max_tr.time_start = data->preempt_timestamp;
629 max_data = max_tr.data[cpu];
630 max_data->saved_latency = tracing_max_latency;
631 max_data->critical_start = data->critical_start;
632 max_data->critical_end = data->critical_end;
634 memcpy(max_data->comm, tsk->comm, TASK_COMM_LEN);
635 max_data->pid = tsk->pid;
636 max_data->uid = task_uid(tsk);
637 max_data->nice = tsk->static_prio - 20 - MAX_RT_PRIO;
638 max_data->policy = tsk->policy;
639 max_data->rt_priority = tsk->rt_priority;
641 /* record this tasks comm */
642 tracing_record_cmdline(tsk);
646 * update_max_tr - snapshot all trace buffers from global_trace to max_tr
648 * @tsk: the task with the latency
649 * @cpu: The cpu that initiated the trace.
651 * Flip the buffers between the @tr and the max_tr and record information
652 * about which task was the cause of this latency.
655 update_max_tr(struct trace_array *tr, struct task_struct *tsk, int cpu)
657 struct ring_buffer *buf = tr->buffer;
659 if (trace_stop_count)
662 WARN_ON_ONCE(!irqs_disabled());
663 if (!current_trace->use_max_tr) {
667 arch_spin_lock(&ftrace_max_lock);
669 tr->buffer = max_tr.buffer;
672 __update_max_tr(tr, tsk, cpu);
673 arch_spin_unlock(&ftrace_max_lock);
677 * update_max_tr_single - only copy one trace over, and reset the rest
679 * @tsk - task with the latency
680 * @cpu - the cpu of the buffer to copy.
682 * Flip the trace of a single CPU buffer between the @tr and the max_tr.
685 update_max_tr_single(struct trace_array *tr, struct task_struct *tsk, int cpu)
689 if (trace_stop_count)
692 WARN_ON_ONCE(!irqs_disabled());
693 if (!current_trace->use_max_tr) {
698 arch_spin_lock(&ftrace_max_lock);
700 ftrace_disable_cpu();
702 ret = ring_buffer_swap_cpu(max_tr.buffer, tr->buffer, cpu);
706 * We failed to swap the buffer due to a commit taking
707 * place on this CPU. We fail to record, but we reset
708 * the max trace buffer (no one writes directly to it)
709 * and flag that it failed.
711 trace_array_printk(&max_tr, _THIS_IP_,
712 "Failed to swap buffers due to commit in progress\n");
717 WARN_ON_ONCE(ret && ret != -EAGAIN && ret != -EBUSY);
719 __update_max_tr(tr, tsk, cpu);
720 arch_spin_unlock(&ftrace_max_lock);
722 #endif /* CONFIG_TRACER_MAX_TRACE */
725 * register_tracer - register a tracer with the ftrace system.
726 * @type - the plugin for the tracer
728 * Register a new plugin tracer.
730 int register_tracer(struct tracer *type)
731 __releases(kernel_lock)
732 __acquires(kernel_lock)
738 pr_info("Tracer must have a name\n");
742 if (strlen(type->name) >= MAX_TRACER_SIZE) {
743 pr_info("Tracer has a name longer than %d\n", MAX_TRACER_SIZE);
747 mutex_lock(&trace_types_lock);
749 tracing_selftest_running = true;
751 for (t = trace_types; t; t = t->next) {
752 if (strcmp(type->name, t->name) == 0) {
754 pr_info("Tracer %s already registered\n",
762 type->set_flag = &dummy_set_flag;
764 type->flags = &dummy_tracer_flags;
766 if (!type->flags->opts)
767 type->flags->opts = dummy_tracer_opt;
768 if (!type->wait_pipe)
769 type->wait_pipe = default_wait_pipe;
772 #ifdef CONFIG_FTRACE_STARTUP_TEST
773 if (type->selftest && !tracing_selftest_disabled) {
774 struct tracer *saved_tracer = current_trace;
775 struct trace_array *tr = &global_trace;
778 * Run a selftest on this tracer.
779 * Here we reset the trace buffer, and set the current
780 * tracer to be this tracer. The tracer can then run some
781 * internal tracing to verify that everything is in order.
782 * If we fail, we do not register this tracer.
784 tracing_reset_online_cpus(tr);
786 current_trace = type;
788 /* If we expanded the buffers, make sure the max is expanded too */
789 if (ring_buffer_expanded && type->use_max_tr)
790 ring_buffer_resize(max_tr.buffer, trace_buf_size);
792 /* the test is responsible for initializing and enabling */
793 pr_info("Testing tracer %s: ", type->name);
794 ret = type->selftest(type, tr);
795 /* the test is responsible for resetting too */
796 current_trace = saved_tracer;
798 printk(KERN_CONT "FAILED!\n");
801 /* Only reset on passing, to avoid touching corrupted buffers */
802 tracing_reset_online_cpus(tr);
804 /* Shrink the max buffer again */
805 if (ring_buffer_expanded && type->use_max_tr)
806 ring_buffer_resize(max_tr.buffer, 1);
808 printk(KERN_CONT "PASSED\n");
812 type->next = trace_types;
816 tracing_selftest_running = false;
817 mutex_unlock(&trace_types_lock);
819 if (ret || !default_bootup_tracer)
822 if (strncmp(default_bootup_tracer, type->name, MAX_TRACER_SIZE))
825 printk(KERN_INFO "Starting tracer '%s'\n", type->name);
826 /* Do we want this tracer to start on bootup? */
827 tracing_set_tracer(type->name);
828 default_bootup_tracer = NULL;
829 /* disable other selftests, since this will break it. */
830 tracing_selftest_disabled = 1;
831 #ifdef CONFIG_FTRACE_STARTUP_TEST
832 printk(KERN_INFO "Disabling FTRACE selftests due to running tracer '%s'\n",
840 void unregister_tracer(struct tracer *type)
844 mutex_lock(&trace_types_lock);
845 for (t = &trace_types; *t; t = &(*t)->next) {
849 pr_info("Tracer %s not registered\n", type->name);
855 if (type == current_trace && tracer_enabled) {
858 if (current_trace->stop)
859 current_trace->stop(&global_trace);
860 current_trace = &nop_trace;
863 mutex_unlock(&trace_types_lock);
866 static void __tracing_reset(struct ring_buffer *buffer, int cpu)
868 ftrace_disable_cpu();
869 ring_buffer_reset_cpu(buffer, cpu);
873 void tracing_reset(struct trace_array *tr, int cpu)
875 struct ring_buffer *buffer = tr->buffer;
877 ring_buffer_record_disable(buffer);
879 /* Make sure all commits have finished */
881 __tracing_reset(buffer, cpu);
883 ring_buffer_record_enable(buffer);
886 void tracing_reset_online_cpus(struct trace_array *tr)
888 struct ring_buffer *buffer = tr->buffer;
891 ring_buffer_record_disable(buffer);
893 /* Make sure all commits have finished */
896 tr->time_start = ftrace_now(tr->cpu);
898 for_each_online_cpu(cpu)
899 __tracing_reset(buffer, cpu);
901 ring_buffer_record_enable(buffer);
904 void tracing_reset_current(int cpu)
906 tracing_reset(&global_trace, cpu);
909 void tracing_reset_current_online_cpus(void)
911 tracing_reset_online_cpus(&global_trace);
914 #define SAVED_CMDLINES 128
915 #define NO_CMDLINE_MAP UINT_MAX
916 static unsigned map_pid_to_cmdline[PID_MAX_DEFAULT+1];
917 static unsigned map_cmdline_to_pid[SAVED_CMDLINES];
918 static char saved_cmdlines[SAVED_CMDLINES][TASK_COMM_LEN];
919 static int cmdline_idx;
920 static arch_spinlock_t trace_cmdline_lock = __ARCH_SPIN_LOCK_UNLOCKED;
922 /* temporary disable recording */
923 static atomic_t trace_record_cmdline_disabled __read_mostly;
925 static void trace_init_cmdlines(void)
927 memset(&map_pid_to_cmdline, NO_CMDLINE_MAP, sizeof(map_pid_to_cmdline));
928 memset(&map_cmdline_to_pid, NO_CMDLINE_MAP, sizeof(map_cmdline_to_pid));
932 int is_tracing_stopped(void)
934 return trace_stop_count;
938 * ftrace_off_permanent - disable all ftrace code permanently
940 * This should only be called when a serious anomally has
941 * been detected. This will turn off the function tracing,
942 * ring buffers, and other tracing utilites. It takes no
943 * locks and can be called from any context.
945 void ftrace_off_permanent(void)
947 tracing_disabled = 1;
949 tracing_off_permanent();
953 * tracing_start - quick start of the tracer
955 * If tracing is enabled but was stopped by tracing_stop,
956 * this will start the tracer back up.
958 void tracing_start(void)
960 struct ring_buffer *buffer;
963 if (tracing_disabled)
966 raw_spin_lock_irqsave(&tracing_start_lock, flags);
967 if (--trace_stop_count) {
968 if (trace_stop_count < 0) {
969 /* Someone screwed up their debugging */
971 trace_stop_count = 0;
976 /* Prevent the buffers from switching */
977 arch_spin_lock(&ftrace_max_lock);
979 buffer = global_trace.buffer;
981 ring_buffer_record_enable(buffer);
983 buffer = max_tr.buffer;
985 ring_buffer_record_enable(buffer);
987 arch_spin_unlock(&ftrace_max_lock);
991 raw_spin_unlock_irqrestore(&tracing_start_lock, flags);
995 * tracing_stop - quick stop of the tracer
997 * Light weight way to stop tracing. Use in conjunction with
1000 void tracing_stop(void)
1002 struct ring_buffer *buffer;
1003 unsigned long flags;
1006 raw_spin_lock_irqsave(&tracing_start_lock, flags);
1007 if (trace_stop_count++)
1010 /* Prevent the buffers from switching */
1011 arch_spin_lock(&ftrace_max_lock);
1013 buffer = global_trace.buffer;
1015 ring_buffer_record_disable(buffer);
1017 buffer = max_tr.buffer;
1019 ring_buffer_record_disable(buffer);
1021 arch_spin_unlock(&ftrace_max_lock);
1024 raw_spin_unlock_irqrestore(&tracing_start_lock, flags);
1027 void trace_stop_cmdline_recording(void);
1029 static void trace_save_cmdline(struct task_struct *tsk)
1033 if (!tsk->pid || unlikely(tsk->pid > PID_MAX_DEFAULT))
1037 * It's not the end of the world if we don't get
1038 * the lock, but we also don't want to spin
1039 * nor do we want to disable interrupts,
1040 * so if we miss here, then better luck next time.
1042 if (!arch_spin_trylock(&trace_cmdline_lock))
1045 idx = map_pid_to_cmdline[tsk->pid];
1046 if (idx == NO_CMDLINE_MAP) {
1047 idx = (cmdline_idx + 1) % SAVED_CMDLINES;
1050 * Check whether the cmdline buffer at idx has a pid
1051 * mapped. We are going to overwrite that entry so we
1052 * need to clear the map_pid_to_cmdline. Otherwise we
1053 * would read the new comm for the old pid.
1055 pid = map_cmdline_to_pid[idx];
1056 if (pid != NO_CMDLINE_MAP)
1057 map_pid_to_cmdline[pid] = NO_CMDLINE_MAP;
1059 map_cmdline_to_pid[idx] = tsk->pid;
1060 map_pid_to_cmdline[tsk->pid] = idx;
1065 memcpy(&saved_cmdlines[idx], tsk->comm, TASK_COMM_LEN);
1067 arch_spin_unlock(&trace_cmdline_lock);
1070 void trace_find_cmdline(int pid, char comm[])
1075 strcpy(comm, "<idle>");
1079 if (WARN_ON_ONCE(pid < 0)) {
1080 strcpy(comm, "<XXX>");
1084 if (pid > PID_MAX_DEFAULT) {
1085 strcpy(comm, "<...>");
1090 arch_spin_lock(&trace_cmdline_lock);
1091 map = map_pid_to_cmdline[pid];
1092 if (map != NO_CMDLINE_MAP)
1093 strcpy(comm, saved_cmdlines[map]);
1095 strcpy(comm, "<...>");
1097 arch_spin_unlock(&trace_cmdline_lock);
1101 void tracing_record_cmdline(struct task_struct *tsk)
1103 if (atomic_read(&trace_record_cmdline_disabled) || !tracer_enabled ||
1107 trace_save_cmdline(tsk);
1111 tracing_generic_entry_update(struct trace_entry *entry, unsigned long flags,
1114 struct task_struct *tsk = current;
1116 entry->preempt_count = pc & 0xff;
1117 entry->pid = (tsk) ? tsk->pid : 0;
1120 #ifdef CONFIG_TRACE_IRQFLAGS_SUPPORT
1121 (irqs_disabled_flags(flags) ? TRACE_FLAG_IRQS_OFF : 0) |
1123 TRACE_FLAG_IRQS_NOSUPPORT |
1125 ((pc & HARDIRQ_MASK) ? TRACE_FLAG_HARDIRQ : 0) |
1126 ((pc & SOFTIRQ_MASK) ? TRACE_FLAG_SOFTIRQ : 0) |
1127 (need_resched() ? TRACE_FLAG_NEED_RESCHED : 0);
1129 EXPORT_SYMBOL_GPL(tracing_generic_entry_update);
1131 struct ring_buffer_event *
1132 trace_buffer_lock_reserve(struct ring_buffer *buffer,
1135 unsigned long flags, int pc)
1137 struct ring_buffer_event *event;
1139 event = ring_buffer_lock_reserve(buffer, len);
1140 if (event != NULL) {
1141 struct trace_entry *ent = ring_buffer_event_data(event);
1143 tracing_generic_entry_update(ent, flags, pc);
1151 __trace_buffer_unlock_commit(struct ring_buffer *buffer,
1152 struct ring_buffer_event *event,
1153 unsigned long flags, int pc,
1156 ring_buffer_unlock_commit(buffer, event);
1158 ftrace_trace_stack(buffer, flags, 6, pc);
1159 ftrace_trace_userstack(buffer, flags, pc);
1165 void trace_buffer_unlock_commit(struct ring_buffer *buffer,
1166 struct ring_buffer_event *event,
1167 unsigned long flags, int pc)
1169 __trace_buffer_unlock_commit(buffer, event, flags, pc, 1);
1172 struct ring_buffer_event *
1173 trace_current_buffer_lock_reserve(struct ring_buffer **current_rb,
1174 int type, unsigned long len,
1175 unsigned long flags, int pc)
1177 *current_rb = global_trace.buffer;
1178 return trace_buffer_lock_reserve(*current_rb,
1179 type, len, flags, pc);
1181 EXPORT_SYMBOL_GPL(trace_current_buffer_lock_reserve);
1183 void trace_current_buffer_unlock_commit(struct ring_buffer *buffer,
1184 struct ring_buffer_event *event,
1185 unsigned long flags, int pc)
1187 __trace_buffer_unlock_commit(buffer, event, flags, pc, 1);
1189 EXPORT_SYMBOL_GPL(trace_current_buffer_unlock_commit);
1191 void trace_nowake_buffer_unlock_commit(struct ring_buffer *buffer,
1192 struct ring_buffer_event *event,
1193 unsigned long flags, int pc)
1195 __trace_buffer_unlock_commit(buffer, event, flags, pc, 0);
1197 EXPORT_SYMBOL_GPL(trace_nowake_buffer_unlock_commit);
1199 void trace_nowake_buffer_unlock_commit_regs(struct ring_buffer *buffer,
1200 struct ring_buffer_event *event,
1201 unsigned long flags, int pc,
1202 struct pt_regs *regs)
1204 ring_buffer_unlock_commit(buffer, event);
1206 ftrace_trace_stack_regs(buffer, flags, 0, pc, regs);
1207 ftrace_trace_userstack(buffer, flags, pc);
1209 EXPORT_SYMBOL_GPL(trace_nowake_buffer_unlock_commit_regs);
1211 void trace_current_buffer_discard_commit(struct ring_buffer *buffer,
1212 struct ring_buffer_event *event)
1214 ring_buffer_discard_commit(buffer, event);
1216 EXPORT_SYMBOL_GPL(trace_current_buffer_discard_commit);
1219 trace_function(struct trace_array *tr,
1220 unsigned long ip, unsigned long parent_ip, unsigned long flags,
1223 struct ftrace_event_call *call = &event_function;
1224 struct ring_buffer *buffer = tr->buffer;
1225 struct ring_buffer_event *event;
1226 struct ftrace_entry *entry;
1228 /* If we are reading the ring buffer, don't trace */
1229 if (unlikely(__this_cpu_read(ftrace_cpu_disabled)))
1232 event = trace_buffer_lock_reserve(buffer, TRACE_FN, sizeof(*entry),
1236 entry = ring_buffer_event_data(event);
1238 entry->parent_ip = parent_ip;
1240 if (!filter_check_discard(call, entry, buffer, event))
1241 ring_buffer_unlock_commit(buffer, event);
1245 ftrace(struct trace_array *tr, struct trace_array_cpu *data,
1246 unsigned long ip, unsigned long parent_ip, unsigned long flags,
1249 if (likely(!atomic_read(&data->disabled)))
1250 trace_function(tr, ip, parent_ip, flags, pc);
1253 #ifdef CONFIG_STACKTRACE
1255 #define FTRACE_STACK_MAX_ENTRIES (PAGE_SIZE / sizeof(unsigned long))
1256 struct ftrace_stack {
1257 unsigned long calls[FTRACE_STACK_MAX_ENTRIES];
1260 static DEFINE_PER_CPU(struct ftrace_stack, ftrace_stack);
1261 static DEFINE_PER_CPU(int, ftrace_stack_reserve);
1263 static void __ftrace_trace_stack(struct ring_buffer *buffer,
1264 unsigned long flags,
1265 int skip, int pc, struct pt_regs *regs)
1267 struct ftrace_event_call *call = &event_kernel_stack;
1268 struct ring_buffer_event *event;
1269 struct stack_entry *entry;
1270 struct stack_trace trace;
1272 int size = FTRACE_STACK_ENTRIES;
1274 trace.nr_entries = 0;
1278 * Since events can happen in NMIs there's no safe way to
1279 * use the per cpu ftrace_stacks. We reserve it and if an interrupt
1280 * or NMI comes in, it will just have to use the default
1281 * FTRACE_STACK_SIZE.
1283 preempt_disable_notrace();
1285 use_stack = ++__get_cpu_var(ftrace_stack_reserve);
1287 * We don't need any atomic variables, just a barrier.
1288 * If an interrupt comes in, we don't care, because it would
1289 * have exited and put the counter back to what we want.
1290 * We just need a barrier to keep gcc from moving things
1294 if (use_stack == 1) {
1295 trace.entries = &__get_cpu_var(ftrace_stack).calls[0];
1296 trace.max_entries = FTRACE_STACK_MAX_ENTRIES;
1299 save_stack_trace_regs(regs, &trace);
1301 save_stack_trace(&trace);
1303 if (trace.nr_entries > size)
1304 size = trace.nr_entries;
1306 /* From now on, use_stack is a boolean */
1309 size *= sizeof(unsigned long);
1311 event = trace_buffer_lock_reserve(buffer, TRACE_STACK,
1312 sizeof(*entry) + size, flags, pc);
1315 entry = ring_buffer_event_data(event);
1317 memset(&entry->caller, 0, size);
1320 memcpy(&entry->caller, trace.entries,
1321 trace.nr_entries * sizeof(unsigned long));
1323 trace.max_entries = FTRACE_STACK_ENTRIES;
1324 trace.entries = entry->caller;
1326 save_stack_trace_regs(regs, &trace);
1328 save_stack_trace(&trace);
1331 entry->size = trace.nr_entries;
1333 if (!filter_check_discard(call, entry, buffer, event))
1334 ring_buffer_unlock_commit(buffer, event);
1337 /* Again, don't let gcc optimize things here */
1339 __get_cpu_var(ftrace_stack_reserve)--;
1340 preempt_enable_notrace();
1344 void ftrace_trace_stack_regs(struct ring_buffer *buffer, unsigned long flags,
1345 int skip, int pc, struct pt_regs *regs)
1347 if (!(trace_flags & TRACE_ITER_STACKTRACE))
1350 __ftrace_trace_stack(buffer, flags, skip, pc, regs);
1353 void ftrace_trace_stack(struct ring_buffer *buffer, unsigned long flags,
1356 if (!(trace_flags & TRACE_ITER_STACKTRACE))
1359 __ftrace_trace_stack(buffer, flags, skip, pc, NULL);
1362 void __trace_stack(struct trace_array *tr, unsigned long flags, int skip,
1365 __ftrace_trace_stack(tr->buffer, flags, skip, pc, NULL);
1369 * trace_dump_stack - record a stack back trace in the trace buffer
1371 void trace_dump_stack(void)
1373 unsigned long flags;
1375 if (tracing_disabled || tracing_selftest_running)
1378 local_save_flags(flags);
1380 /* skipping 3 traces, seems to get us at the caller of this function */
1381 __ftrace_trace_stack(global_trace.buffer, flags, 3, preempt_count(), NULL);
1384 static DEFINE_PER_CPU(int, user_stack_count);
1387 ftrace_trace_userstack(struct ring_buffer *buffer, unsigned long flags, int pc)
1389 struct ftrace_event_call *call = &event_user_stack;
1390 struct ring_buffer_event *event;
1391 struct userstack_entry *entry;
1392 struct stack_trace trace;
1394 if (!(trace_flags & TRACE_ITER_USERSTACKTRACE))
1398 * NMIs can not handle page faults, even with fix ups.
1399 * The save user stack can (and often does) fault.
1401 if (unlikely(in_nmi()))
1405 * prevent recursion, since the user stack tracing may
1406 * trigger other kernel events.
1409 if (__this_cpu_read(user_stack_count))
1412 __this_cpu_inc(user_stack_count);
1414 event = trace_buffer_lock_reserve(buffer, TRACE_USER_STACK,
1415 sizeof(*entry), flags, pc);
1417 goto out_drop_count;
1418 entry = ring_buffer_event_data(event);
1420 entry->tgid = current->tgid;
1421 memset(&entry->caller, 0, sizeof(entry->caller));
1423 trace.nr_entries = 0;
1424 trace.max_entries = FTRACE_STACK_ENTRIES;
1426 trace.entries = entry->caller;
1428 save_stack_trace_user(&trace);
1429 if (!filter_check_discard(call, entry, buffer, event))
1430 ring_buffer_unlock_commit(buffer, event);
1433 __this_cpu_dec(user_stack_count);
1439 static void __trace_userstack(struct trace_array *tr, unsigned long flags)
1441 ftrace_trace_userstack(tr, flags, preempt_count());
1445 #endif /* CONFIG_STACKTRACE */
1448 * trace_vbprintk - write binary msg to tracing buffer
1451 int trace_vbprintk(unsigned long ip, const char *fmt, va_list args)
1453 static arch_spinlock_t trace_buf_lock =
1454 (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
1455 static u32 trace_buf[TRACE_BUF_SIZE];
1457 struct ftrace_event_call *call = &event_bprint;
1458 struct ring_buffer_event *event;
1459 struct ring_buffer *buffer;
1460 struct trace_array *tr = &global_trace;
1461 struct trace_array_cpu *data;
1462 struct bprint_entry *entry;
1463 unsigned long flags;
1465 int cpu, len = 0, size, pc;
1467 if (unlikely(tracing_selftest_running || tracing_disabled))
1470 /* Don't pollute graph traces with trace_vprintk internals */
1471 pause_graph_tracing();
1473 pc = preempt_count();
1474 preempt_disable_notrace();
1475 cpu = raw_smp_processor_id();
1476 data = tr->data[cpu];
1478 disable = atomic_inc_return(&data->disabled);
1479 if (unlikely(disable != 1))
1482 /* Lockdep uses trace_printk for lock tracing */
1483 local_irq_save(flags);
1484 arch_spin_lock(&trace_buf_lock);
1485 len = vbin_printf(trace_buf, TRACE_BUF_SIZE, fmt, args);
1487 if (len > TRACE_BUF_SIZE || len < 0)
1490 size = sizeof(*entry) + sizeof(u32) * len;
1491 buffer = tr->buffer;
1492 event = trace_buffer_lock_reserve(buffer, TRACE_BPRINT, size,
1496 entry = ring_buffer_event_data(event);
1500 memcpy(entry->buf, trace_buf, sizeof(u32) * len);
1501 if (!filter_check_discard(call, entry, buffer, event)) {
1502 ring_buffer_unlock_commit(buffer, event);
1503 ftrace_trace_stack(buffer, flags, 6, pc);
1507 arch_spin_unlock(&trace_buf_lock);
1508 local_irq_restore(flags);
1511 atomic_dec_return(&data->disabled);
1512 preempt_enable_notrace();
1513 unpause_graph_tracing();
1517 EXPORT_SYMBOL_GPL(trace_vbprintk);
1519 int trace_array_printk(struct trace_array *tr,
1520 unsigned long ip, const char *fmt, ...)
1525 if (!(trace_flags & TRACE_ITER_PRINTK))
1529 ret = trace_array_vprintk(tr, ip, fmt, ap);
1534 int trace_array_vprintk(struct trace_array *tr,
1535 unsigned long ip, const char *fmt, va_list args)
1537 static arch_spinlock_t trace_buf_lock = __ARCH_SPIN_LOCK_UNLOCKED;
1538 static char trace_buf[TRACE_BUF_SIZE];
1540 struct ftrace_event_call *call = &event_print;
1541 struct ring_buffer_event *event;
1542 struct ring_buffer *buffer;
1543 struct trace_array_cpu *data;
1544 int cpu, len = 0, size, pc;
1545 struct print_entry *entry;
1546 unsigned long irq_flags;
1549 if (tracing_disabled || tracing_selftest_running)
1552 pc = preempt_count();
1553 preempt_disable_notrace();
1554 cpu = raw_smp_processor_id();
1555 data = tr->data[cpu];
1557 disable = atomic_inc_return(&data->disabled);
1558 if (unlikely(disable != 1))
1561 pause_graph_tracing();
1562 raw_local_irq_save(irq_flags);
1563 arch_spin_lock(&trace_buf_lock);
1564 len = vsnprintf(trace_buf, TRACE_BUF_SIZE, fmt, args);
1566 size = sizeof(*entry) + len + 1;
1567 buffer = tr->buffer;
1568 event = trace_buffer_lock_reserve(buffer, TRACE_PRINT, size,
1572 entry = ring_buffer_event_data(event);
1575 memcpy(&entry->buf, trace_buf, len);
1576 entry->buf[len] = '\0';
1577 if (!filter_check_discard(call, entry, buffer, event)) {
1578 ring_buffer_unlock_commit(buffer, event);
1579 ftrace_trace_stack(buffer, irq_flags, 6, pc);
1583 arch_spin_unlock(&trace_buf_lock);
1584 raw_local_irq_restore(irq_flags);
1585 unpause_graph_tracing();
1587 atomic_dec_return(&data->disabled);
1588 preempt_enable_notrace();
1593 int trace_vprintk(unsigned long ip, const char *fmt, va_list args)
1595 return trace_array_vprintk(&global_trace, ip, fmt, args);
1597 EXPORT_SYMBOL_GPL(trace_vprintk);
1599 static void trace_iterator_increment(struct trace_iterator *iter)
1601 /* Don't allow ftrace to trace into the ring buffers */
1602 ftrace_disable_cpu();
1605 if (iter->buffer_iter[iter->cpu])
1606 ring_buffer_read(iter->buffer_iter[iter->cpu], NULL);
1608 ftrace_enable_cpu();
1611 static struct trace_entry *
1612 peek_next_entry(struct trace_iterator *iter, int cpu, u64 *ts,
1613 unsigned long *lost_events)
1615 struct ring_buffer_event *event;
1616 struct ring_buffer_iter *buf_iter = iter->buffer_iter[cpu];
1618 /* Don't allow ftrace to trace into the ring buffers */
1619 ftrace_disable_cpu();
1622 event = ring_buffer_iter_peek(buf_iter, ts);
1624 event = ring_buffer_peek(iter->tr->buffer, cpu, ts,
1627 ftrace_enable_cpu();
1630 iter->ent_size = ring_buffer_event_length(event);
1631 return ring_buffer_event_data(event);
1637 static struct trace_entry *
1638 __find_next_entry(struct trace_iterator *iter, int *ent_cpu,
1639 unsigned long *missing_events, u64 *ent_ts)
1641 struct ring_buffer *buffer = iter->tr->buffer;
1642 struct trace_entry *ent, *next = NULL;
1643 unsigned long lost_events = 0, next_lost = 0;
1644 int cpu_file = iter->cpu_file;
1645 u64 next_ts = 0, ts;
1650 * If we are in a per_cpu trace file, don't bother by iterating over
1651 * all cpu and peek directly.
1653 if (cpu_file > TRACE_PIPE_ALL_CPU) {
1654 if (ring_buffer_empty_cpu(buffer, cpu_file))
1656 ent = peek_next_entry(iter, cpu_file, ent_ts, missing_events);
1658 *ent_cpu = cpu_file;
1663 for_each_tracing_cpu(cpu) {
1665 if (ring_buffer_empty_cpu(buffer, cpu))
1668 ent = peek_next_entry(iter, cpu, &ts, &lost_events);
1671 * Pick the entry with the smallest timestamp:
1673 if (ent && (!next || ts < next_ts)) {
1677 next_lost = lost_events;
1682 *ent_cpu = next_cpu;
1688 *missing_events = next_lost;
1693 /* Find the next real entry, without updating the iterator itself */
1694 struct trace_entry *trace_find_next_entry(struct trace_iterator *iter,
1695 int *ent_cpu, u64 *ent_ts)
1697 return __find_next_entry(iter, ent_cpu, NULL, ent_ts);
1700 /* Find the next real entry, and increment the iterator to the next entry */
1701 void *trace_find_next_entry_inc(struct trace_iterator *iter)
1703 iter->ent = __find_next_entry(iter, &iter->cpu,
1704 &iter->lost_events, &iter->ts);
1707 trace_iterator_increment(iter);
1709 return iter->ent ? iter : NULL;
1712 static void trace_consume(struct trace_iterator *iter)
1714 /* Don't allow ftrace to trace into the ring buffers */
1715 ftrace_disable_cpu();
1716 ring_buffer_consume(iter->tr->buffer, iter->cpu, &iter->ts,
1717 &iter->lost_events);
1718 ftrace_enable_cpu();
1721 static void *s_next(struct seq_file *m, void *v, loff_t *pos)
1723 struct trace_iterator *iter = m->private;
1727 WARN_ON_ONCE(iter->leftover);
1731 /* can't go backwards */
1736 ent = trace_find_next_entry_inc(iter);
1740 while (ent && iter->idx < i)
1741 ent = trace_find_next_entry_inc(iter);
1748 void tracing_iter_reset(struct trace_iterator *iter, int cpu)
1750 struct trace_array *tr = iter->tr;
1751 struct ring_buffer_event *event;
1752 struct ring_buffer_iter *buf_iter;
1753 unsigned long entries = 0;
1756 tr->data[cpu]->skipped_entries = 0;
1758 if (!iter->buffer_iter[cpu])
1761 buf_iter = iter->buffer_iter[cpu];
1762 ring_buffer_iter_reset(buf_iter);
1765 * We could have the case with the max latency tracers
1766 * that a reset never took place on a cpu. This is evident
1767 * by the timestamp being before the start of the buffer.
1769 while ((event = ring_buffer_iter_peek(buf_iter, &ts))) {
1770 if (ts >= iter->tr->time_start)
1773 ring_buffer_read(buf_iter, NULL);
1776 tr->data[cpu]->skipped_entries = entries;
1780 * The current tracer is copied to avoid a global locking
1783 static void *s_start(struct seq_file *m, loff_t *pos)
1785 struct trace_iterator *iter = m->private;
1786 static struct tracer *old_tracer;
1787 int cpu_file = iter->cpu_file;
1792 /* copy the tracer to avoid using a global lock all around */
1793 mutex_lock(&trace_types_lock);
1794 if (unlikely(old_tracer != current_trace && current_trace)) {
1795 old_tracer = current_trace;
1796 *iter->trace = *current_trace;
1798 mutex_unlock(&trace_types_lock);
1800 atomic_inc(&trace_record_cmdline_disabled);
1802 if (*pos != iter->pos) {
1807 ftrace_disable_cpu();
1809 if (cpu_file == TRACE_PIPE_ALL_CPU) {
1810 for_each_tracing_cpu(cpu)
1811 tracing_iter_reset(iter, cpu);
1813 tracing_iter_reset(iter, cpu_file);
1815 ftrace_enable_cpu();
1818 for (p = iter; p && l < *pos; p = s_next(m, p, &l))
1823 * If we overflowed the seq_file before, then we want
1824 * to just reuse the trace_seq buffer again.
1830 p = s_next(m, p, &l);
1834 trace_event_read_lock();
1835 trace_access_lock(cpu_file);
1839 static void s_stop(struct seq_file *m, void *p)
1841 struct trace_iterator *iter = m->private;
1843 atomic_dec(&trace_record_cmdline_disabled);
1844 trace_access_unlock(iter->cpu_file);
1845 trace_event_read_unlock();
1849 get_total_entries(struct trace_array *tr, unsigned long *total, unsigned long *entries)
1851 unsigned long count;
1857 for_each_tracing_cpu(cpu) {
1858 count = ring_buffer_entries_cpu(tr->buffer, cpu);
1860 * If this buffer has skipped entries, then we hold all
1861 * entries for the trace and we need to ignore the
1862 * ones before the time stamp.
1864 if (tr->data[cpu]->skipped_entries) {
1865 count -= tr->data[cpu]->skipped_entries;
1866 /* total is the same as the entries */
1870 ring_buffer_overrun_cpu(tr->buffer, cpu);
1875 static void print_lat_help_header(struct seq_file *m)
1877 seq_puts(m, "# _------=> CPU# \n");
1878 seq_puts(m, "# / _-----=> irqs-off \n");
1879 seq_puts(m, "# | / _----=> need-resched \n");
1880 seq_puts(m, "# || / _---=> hardirq/softirq \n");
1881 seq_puts(m, "# ||| / _--=> preempt-depth \n");
1882 seq_puts(m, "# |||| / delay \n");
1883 seq_puts(m, "# cmd pid ||||| time | caller \n");
1884 seq_puts(m, "# \\ / ||||| \\ | / \n");
1887 static void print_event_info(struct trace_array *tr, struct seq_file *m)
1889 unsigned long total;
1890 unsigned long entries;
1892 get_total_entries(tr, &total, &entries);
1893 seq_printf(m, "# entries-in-buffer/entries-written: %lu/%lu #P:%d\n",
1894 entries, total, num_online_cpus());
1898 static void print_func_help_header(struct trace_array *tr, struct seq_file *m)
1900 print_event_info(tr, m);
1901 seq_puts(m, "# TASK-PID CPU# TIMESTAMP FUNCTION\n");
1902 seq_puts(m, "# | | | | |\n");
1905 static void print_func_help_header_irq(struct trace_array *tr, struct seq_file *m)
1907 print_event_info(tr, m);
1908 seq_puts(m, "# _-----=> irqs-off\n");
1909 seq_puts(m, "# / _----=> need-resched\n");
1910 seq_puts(m, "# | / _---=> hardirq/softirq\n");
1911 seq_puts(m, "# || / _--=> preempt-depth\n");
1912 seq_puts(m, "# ||| / delay\n");
1913 seq_puts(m, "# TASK-PID CPU# |||| TIMESTAMP FUNCTION\n");
1914 seq_puts(m, "# | | | |||| | |\n");
1918 print_trace_header(struct seq_file *m, struct trace_iterator *iter)
1920 unsigned long sym_flags = (trace_flags & TRACE_ITER_SYM_MASK);
1921 struct trace_array *tr = iter->tr;
1922 struct trace_array_cpu *data = tr->data[tr->cpu];
1923 struct tracer *type = current_trace;
1924 unsigned long entries;
1925 unsigned long total;
1926 const char *name = "preemption";
1931 get_total_entries(tr, &total, &entries);
1933 seq_printf(m, "# %s latency trace v1.1.5 on %s\n",
1935 seq_puts(m, "# -----------------------------------"
1936 "---------------------------------\n");
1937 seq_printf(m, "# latency: %lu us, #%lu/%lu, CPU#%d |"
1938 " (M:%s VP:%d, KP:%d, SP:%d HP:%d",
1939 nsecs_to_usecs(data->saved_latency),
1943 #if defined(CONFIG_PREEMPT_NONE)
1945 #elif defined(CONFIG_PREEMPT_VOLUNTARY)
1947 #elif defined(CONFIG_PREEMPT)
1952 /* These are reserved for later use */
1955 seq_printf(m, " #P:%d)\n", num_online_cpus());
1959 seq_puts(m, "# -----------------\n");
1960 seq_printf(m, "# | task: %.16s-%d "
1961 "(uid:%d nice:%ld policy:%ld rt_prio:%ld)\n",
1962 data->comm, data->pid, data->uid, data->nice,
1963 data->policy, data->rt_priority);
1964 seq_puts(m, "# -----------------\n");
1966 if (data->critical_start) {
1967 seq_puts(m, "# => started at: ");
1968 seq_print_ip_sym(&iter->seq, data->critical_start, sym_flags);
1969 trace_print_seq(m, &iter->seq);
1970 seq_puts(m, "\n# => ended at: ");
1971 seq_print_ip_sym(&iter->seq, data->critical_end, sym_flags);
1972 trace_print_seq(m, &iter->seq);
1973 seq_puts(m, "\n#\n");
1979 static void test_cpu_buff_start(struct trace_iterator *iter)
1981 struct trace_seq *s = &iter->seq;
1983 if (!(trace_flags & TRACE_ITER_ANNOTATE))
1986 if (!(iter->iter_flags & TRACE_FILE_ANNOTATE))
1989 if (cpumask_test_cpu(iter->cpu, iter->started))
1992 if (iter->tr->data[iter->cpu]->skipped_entries)
1995 cpumask_set_cpu(iter->cpu, iter->started);
1997 /* Don't print started cpu buffer for the first entry of the trace */
1999 trace_seq_printf(s, "##### CPU %u buffer started ####\n",
2003 static enum print_line_t print_trace_fmt(struct trace_iterator *iter)
2005 struct trace_seq *s = &iter->seq;
2006 unsigned long sym_flags = (trace_flags & TRACE_ITER_SYM_MASK);
2007 struct trace_entry *entry;
2008 struct trace_event *event;
2012 test_cpu_buff_start(iter);
2014 event = ftrace_find_event(entry->type);
2016 if (trace_flags & TRACE_ITER_CONTEXT_INFO) {
2017 if (iter->iter_flags & TRACE_FILE_LAT_FMT) {
2018 if (!trace_print_lat_context(iter))
2021 if (!trace_print_context(iter))
2027 return event->funcs->trace(iter, sym_flags, event);
2029 if (!trace_seq_printf(s, "Unknown type %d\n", entry->type))
2032 return TRACE_TYPE_HANDLED;
2034 return TRACE_TYPE_PARTIAL_LINE;
2037 static enum print_line_t print_raw_fmt(struct trace_iterator *iter)
2039 struct trace_seq *s = &iter->seq;
2040 struct trace_entry *entry;
2041 struct trace_event *event;
2045 if (trace_flags & TRACE_ITER_CONTEXT_INFO) {
2046 if (!trace_seq_printf(s, "%d %d %llu ",
2047 entry->pid, iter->cpu, iter->ts))
2051 event = ftrace_find_event(entry->type);
2053 return event->funcs->raw(iter, 0, event);
2055 if (!trace_seq_printf(s, "%d ?\n", entry->type))
2058 return TRACE_TYPE_HANDLED;
2060 return TRACE_TYPE_PARTIAL_LINE;
2063 static enum print_line_t print_hex_fmt(struct trace_iterator *iter)
2065 struct trace_seq *s = &iter->seq;
2066 unsigned char newline = '\n';
2067 struct trace_entry *entry;
2068 struct trace_event *event;
2072 if (trace_flags & TRACE_ITER_CONTEXT_INFO) {
2073 SEQ_PUT_HEX_FIELD_RET(s, entry->pid);
2074 SEQ_PUT_HEX_FIELD_RET(s, iter->cpu);
2075 SEQ_PUT_HEX_FIELD_RET(s, iter->ts);
2078 event = ftrace_find_event(entry->type);
2080 enum print_line_t ret = event->funcs->hex(iter, 0, event);
2081 if (ret != TRACE_TYPE_HANDLED)
2085 SEQ_PUT_FIELD_RET(s, newline);
2087 return TRACE_TYPE_HANDLED;
2090 static enum print_line_t print_bin_fmt(struct trace_iterator *iter)
2092 struct trace_seq *s = &iter->seq;
2093 struct trace_entry *entry;
2094 struct trace_event *event;
2098 if (trace_flags & TRACE_ITER_CONTEXT_INFO) {
2099 SEQ_PUT_FIELD_RET(s, entry->pid);
2100 SEQ_PUT_FIELD_RET(s, iter->cpu);
2101 SEQ_PUT_FIELD_RET(s, iter->ts);
2104 event = ftrace_find_event(entry->type);
2105 return event ? event->funcs->binary(iter, 0, event) :
2109 int trace_empty(struct trace_iterator *iter)
2113 /* If we are looking at one CPU buffer, only check that one */
2114 if (iter->cpu_file != TRACE_PIPE_ALL_CPU) {
2115 cpu = iter->cpu_file;
2116 if (iter->buffer_iter[cpu]) {
2117 if (!ring_buffer_iter_empty(iter->buffer_iter[cpu]))
2120 if (!ring_buffer_empty_cpu(iter->tr->buffer, cpu))
2126 for_each_tracing_cpu(cpu) {
2127 if (iter->buffer_iter[cpu]) {
2128 if (!ring_buffer_iter_empty(iter->buffer_iter[cpu]))
2131 if (!ring_buffer_empty_cpu(iter->tr->buffer, cpu))
2139 /* Called with trace_event_read_lock() held. */
2140 enum print_line_t print_trace_line(struct trace_iterator *iter)
2142 enum print_line_t ret;
2144 if (iter->lost_events &&
2145 !trace_seq_printf(&iter->seq, "CPU:%d [LOST %lu EVENTS]\n",
2146 iter->cpu, iter->lost_events))
2147 return TRACE_TYPE_PARTIAL_LINE;
2149 if (iter->trace && iter->trace->print_line) {
2150 ret = iter->trace->print_line(iter);
2151 if (ret != TRACE_TYPE_UNHANDLED)
2155 if (iter->ent->type == TRACE_BPRINT &&
2156 trace_flags & TRACE_ITER_PRINTK &&
2157 trace_flags & TRACE_ITER_PRINTK_MSGONLY)
2158 return trace_print_bprintk_msg_only(iter);
2160 if (iter->ent->type == TRACE_PRINT &&
2161 trace_flags & TRACE_ITER_PRINTK &&
2162 trace_flags & TRACE_ITER_PRINTK_MSGONLY)
2163 return trace_print_printk_msg_only(iter);
2165 if (trace_flags & TRACE_ITER_BIN)
2166 return print_bin_fmt(iter);
2168 if (trace_flags & TRACE_ITER_HEX)
2169 return print_hex_fmt(iter);
2171 if (trace_flags & TRACE_ITER_RAW)
2172 return print_raw_fmt(iter);
2174 return print_trace_fmt(iter);
2177 void trace_latency_header(struct seq_file *m)
2179 struct trace_iterator *iter = m->private;
2181 /* print nothing if the buffers are empty */
2182 if (trace_empty(iter))
2185 if (iter->iter_flags & TRACE_FILE_LAT_FMT)
2186 print_trace_header(m, iter);
2188 if (!(trace_flags & TRACE_ITER_VERBOSE))
2189 print_lat_help_header(m);
2192 void trace_default_header(struct seq_file *m)
2194 struct trace_iterator *iter = m->private;
2196 if (!(trace_flags & TRACE_ITER_CONTEXT_INFO))
2199 if (iter->iter_flags & TRACE_FILE_LAT_FMT) {
2200 /* print nothing if the buffers are empty */
2201 if (trace_empty(iter))
2203 print_trace_header(m, iter);
2204 if (!(trace_flags & TRACE_ITER_VERBOSE))
2205 print_lat_help_header(m);
2207 if (!(trace_flags & TRACE_ITER_VERBOSE)) {
2208 if (trace_flags & TRACE_ITER_IRQ_INFO)
2209 print_func_help_header_irq(iter->tr, m);
2211 print_func_help_header(iter->tr, m);
2216 static void test_ftrace_alive(struct seq_file *m)
2218 if (!ftrace_is_dead())
2220 seq_printf(m, "# WARNING: FUNCTION TRACING IS CORRUPTED\n");
2221 seq_printf(m, "# MAY BE MISSING FUNCTION EVENTS\n");
2224 static int s_show(struct seq_file *m, void *v)
2226 struct trace_iterator *iter = v;
2229 if (iter->ent == NULL) {
2231 seq_printf(m, "# tracer: %s\n", iter->trace->name);
2233 test_ftrace_alive(m);
2235 if (iter->trace && iter->trace->print_header)
2236 iter->trace->print_header(m);
2238 trace_default_header(m);
2240 } else if (iter->leftover) {
2242 * If we filled the seq_file buffer earlier, we
2243 * want to just show it now.
2245 ret = trace_print_seq(m, &iter->seq);
2247 /* ret should this time be zero, but you never know */
2248 iter->leftover = ret;
2251 print_trace_line(iter);
2252 ret = trace_print_seq(m, &iter->seq);
2254 * If we overflow the seq_file buffer, then it will
2255 * ask us for this data again at start up.
2257 * ret is 0 if seq_file write succeeded.
2260 iter->leftover = ret;
2266 static const struct seq_operations tracer_seq_ops = {
2273 static struct trace_iterator *
2274 __tracing_open(struct inode *inode, struct file *file)
2276 long cpu_file = (long) inode->i_private;
2277 void *fail_ret = ERR_PTR(-ENOMEM);
2278 struct trace_iterator *iter;
2282 if (tracing_disabled)
2283 return ERR_PTR(-ENODEV);
2285 iter = kzalloc(sizeof(*iter), GFP_KERNEL);
2287 return ERR_PTR(-ENOMEM);
2290 * We make a copy of the current tracer to avoid concurrent
2291 * changes on it while we are reading.
2293 mutex_lock(&trace_types_lock);
2294 iter->trace = kzalloc(sizeof(*iter->trace), GFP_KERNEL);
2299 *iter->trace = *current_trace;
2301 if (!zalloc_cpumask_var(&iter->started, GFP_KERNEL))
2304 if (current_trace && current_trace->print_max)
2307 iter->tr = &global_trace;
2309 mutex_init(&iter->mutex);
2310 iter->cpu_file = cpu_file;
2312 /* Notify the tracer early; before we stop tracing. */
2313 if (iter->trace && iter->trace->open)
2314 iter->trace->open(iter);
2316 /* Annotate start of buffers if we had overruns */
2317 if (ring_buffer_overruns(iter->tr->buffer))
2318 iter->iter_flags |= TRACE_FILE_ANNOTATE;
2320 /* stop the trace while dumping */
2323 if (iter->cpu_file == TRACE_PIPE_ALL_CPU) {
2324 for_each_tracing_cpu(cpu) {
2325 iter->buffer_iter[cpu] =
2326 ring_buffer_read_prepare(iter->tr->buffer, cpu);
2328 ring_buffer_read_prepare_sync();
2329 for_each_tracing_cpu(cpu) {
2330 ring_buffer_read_start(iter->buffer_iter[cpu]);
2331 tracing_iter_reset(iter, cpu);
2334 cpu = iter->cpu_file;
2335 iter->buffer_iter[cpu] =
2336 ring_buffer_read_prepare(iter->tr->buffer, cpu);
2337 ring_buffer_read_prepare_sync();
2338 ring_buffer_read_start(iter->buffer_iter[cpu]);
2339 tracing_iter_reset(iter, cpu);
2342 ret = seq_open(file, &tracer_seq_ops);
2344 fail_ret = ERR_PTR(ret);
2348 m = file->private_data;
2351 mutex_unlock(&trace_types_lock);
2356 for_each_tracing_cpu(cpu) {
2357 if (iter->buffer_iter[cpu])
2358 ring_buffer_read_finish(iter->buffer_iter[cpu]);
2360 free_cpumask_var(iter->started);
2363 mutex_unlock(&trace_types_lock);
2370 int tracing_open_generic(struct inode *inode, struct file *filp)
2372 if (tracing_disabled)
2375 filp->private_data = inode->i_private;
2379 static int tracing_release(struct inode *inode, struct file *file)
2381 struct seq_file *m = file->private_data;
2382 struct trace_iterator *iter;
2385 if (!(file->f_mode & FMODE_READ))
2390 mutex_lock(&trace_types_lock);
2391 for_each_tracing_cpu(cpu) {
2392 if (iter->buffer_iter[cpu])
2393 ring_buffer_read_finish(iter->buffer_iter[cpu]);
2396 if (iter->trace && iter->trace->close)
2397 iter->trace->close(iter);
2399 /* reenable tracing if it was previously enabled */
2401 mutex_unlock(&trace_types_lock);
2403 seq_release(inode, file);
2404 mutex_destroy(&iter->mutex);
2405 free_cpumask_var(iter->started);
2411 static int tracing_open(struct inode *inode, struct file *file)
2413 struct trace_iterator *iter;
2416 /* If this file was open for write, then erase contents */
2417 if ((file->f_mode & FMODE_WRITE) &&
2418 (file->f_flags & O_TRUNC)) {
2419 long cpu = (long) inode->i_private;
2421 if (cpu == TRACE_PIPE_ALL_CPU)
2422 tracing_reset_online_cpus(&global_trace);
2424 tracing_reset(&global_trace, cpu);
2427 if (file->f_mode & FMODE_READ) {
2428 iter = __tracing_open(inode, file);
2430 ret = PTR_ERR(iter);
2431 else if (trace_flags & TRACE_ITER_LATENCY_FMT)
2432 iter->iter_flags |= TRACE_FILE_LAT_FMT;
2438 t_next(struct seq_file *m, void *v, loff_t *pos)
2440 struct tracer *t = v;
2450 static void *t_start(struct seq_file *m, loff_t *pos)
2455 mutex_lock(&trace_types_lock);
2456 for (t = trace_types; t && l < *pos; t = t_next(m, t, &l))
2462 static void t_stop(struct seq_file *m, void *p)
2464 mutex_unlock(&trace_types_lock);
2467 static int t_show(struct seq_file *m, void *v)
2469 struct tracer *t = v;
2474 seq_printf(m, "%s", t->name);
2483 static const struct seq_operations show_traces_seq_ops = {
2490 static int show_traces_open(struct inode *inode, struct file *file)
2492 if (tracing_disabled)
2495 return seq_open(file, &show_traces_seq_ops);
2499 tracing_write_stub(struct file *filp, const char __user *ubuf,
2500 size_t count, loff_t *ppos)
2505 static loff_t tracing_seek(struct file *file, loff_t offset, int origin)
2507 if (file->f_mode & FMODE_READ)
2508 return seq_lseek(file, offset, origin);
2513 static const struct file_operations tracing_fops = {
2514 .open = tracing_open,
2516 .write = tracing_write_stub,
2517 .llseek = tracing_seek,
2518 .release = tracing_release,
2521 static const struct file_operations show_traces_fops = {
2522 .open = show_traces_open,
2524 .release = seq_release,
2525 .llseek = seq_lseek,
2529 * Only trace on a CPU if the bitmask is set:
2531 static cpumask_var_t tracing_cpumask;
2534 * The tracer itself will not take this lock, but still we want
2535 * to provide a consistent cpumask to user-space:
2537 static DEFINE_MUTEX(tracing_cpumask_update_lock);
2540 * Temporary storage for the character representation of the
2541 * CPU bitmask (and one more byte for the newline):
2543 static char mask_str[NR_CPUS + 1];
2546 tracing_cpumask_read(struct file *filp, char __user *ubuf,
2547 size_t count, loff_t *ppos)
2551 mutex_lock(&tracing_cpumask_update_lock);
2553 len = cpumask_scnprintf(mask_str, count, tracing_cpumask);
2554 if (count - len < 2) {
2558 len += sprintf(mask_str + len, "\n");
2559 count = simple_read_from_buffer(ubuf, count, ppos, mask_str, NR_CPUS+1);
2562 mutex_unlock(&tracing_cpumask_update_lock);
2568 tracing_cpumask_write(struct file *filp, const char __user *ubuf,
2569 size_t count, loff_t *ppos)
2572 cpumask_var_t tracing_cpumask_new;
2574 if (!alloc_cpumask_var(&tracing_cpumask_new, GFP_KERNEL))
2577 err = cpumask_parse_user(ubuf, count, tracing_cpumask_new);
2581 mutex_lock(&tracing_cpumask_update_lock);
2583 local_irq_disable();
2584 arch_spin_lock(&ftrace_max_lock);
2585 for_each_tracing_cpu(cpu) {
2587 * Increase/decrease the disabled counter if we are
2588 * about to flip a bit in the cpumask:
2590 if (cpumask_test_cpu(cpu, tracing_cpumask) &&
2591 !cpumask_test_cpu(cpu, tracing_cpumask_new)) {
2592 atomic_inc(&global_trace.data[cpu]->disabled);
2594 if (!cpumask_test_cpu(cpu, tracing_cpumask) &&
2595 cpumask_test_cpu(cpu, tracing_cpumask_new)) {
2596 atomic_dec(&global_trace.data[cpu]->disabled);
2599 arch_spin_unlock(&ftrace_max_lock);
2602 cpumask_copy(tracing_cpumask, tracing_cpumask_new);
2604 mutex_unlock(&tracing_cpumask_update_lock);
2605 free_cpumask_var(tracing_cpumask_new);
2610 free_cpumask_var(tracing_cpumask_new);
2615 static const struct file_operations tracing_cpumask_fops = {
2616 .open = tracing_open_generic,
2617 .read = tracing_cpumask_read,
2618 .write = tracing_cpumask_write,
2619 .llseek = generic_file_llseek,
2622 static int tracing_trace_options_show(struct seq_file *m, void *v)
2624 struct tracer_opt *trace_opts;
2628 mutex_lock(&trace_types_lock);
2629 tracer_flags = current_trace->flags->val;
2630 trace_opts = current_trace->flags->opts;
2632 for (i = 0; trace_options[i]; i++) {
2633 if (trace_flags & (1 << i))
2634 seq_printf(m, "%s\n", trace_options[i]);
2636 seq_printf(m, "no%s\n", trace_options[i]);
2639 for (i = 0; trace_opts[i].name; i++) {
2640 if (tracer_flags & trace_opts[i].bit)
2641 seq_printf(m, "%s\n", trace_opts[i].name);
2643 seq_printf(m, "no%s\n", trace_opts[i].name);
2645 mutex_unlock(&trace_types_lock);
2650 static int __set_tracer_option(struct tracer *trace,
2651 struct tracer_flags *tracer_flags,
2652 struct tracer_opt *opts, int neg)
2656 ret = trace->set_flag(tracer_flags->val, opts->bit, !neg);
2661 tracer_flags->val &= ~opts->bit;
2663 tracer_flags->val |= opts->bit;
2667 /* Try to assign a tracer specific option */
2668 static int set_tracer_option(struct tracer *trace, char *cmp, int neg)
2670 struct tracer_flags *tracer_flags = trace->flags;
2671 struct tracer_opt *opts = NULL;
2674 for (i = 0; tracer_flags->opts[i].name; i++) {
2675 opts = &tracer_flags->opts[i];
2677 if (strcmp(cmp, opts->name) == 0)
2678 return __set_tracer_option(trace, trace->flags,
2685 static void set_tracer_flags(unsigned int mask, int enabled)
2687 /* do nothing if flag is already set */
2688 if (!!(trace_flags & mask) == !!enabled)
2692 trace_flags |= mask;
2694 trace_flags &= ~mask;
2696 if (mask == TRACE_ITER_RECORD_CMD)
2697 trace_event_enable_cmd_record(enabled);
2699 if (mask == TRACE_ITER_OVERWRITE)
2700 ring_buffer_change_overwrite(global_trace.buffer, enabled);
2704 tracing_trace_options_write(struct file *filp, const char __user *ubuf,
2705 size_t cnt, loff_t *ppos)
2713 if (cnt >= sizeof(buf))
2716 if (copy_from_user(&buf, ubuf, cnt))
2720 cmp = strstrip(buf);
2722 if (strncmp(cmp, "no", 2) == 0) {
2727 for (i = 0; trace_options[i]; i++) {
2728 if (strcmp(cmp, trace_options[i]) == 0) {
2729 set_tracer_flags(1 << i, !neg);
2734 /* If no option could be set, test the specific tracer options */
2735 if (!trace_options[i]) {
2736 mutex_lock(&trace_types_lock);
2737 ret = set_tracer_option(current_trace, cmp, neg);
2738 mutex_unlock(&trace_types_lock);
2748 static int tracing_trace_options_open(struct inode *inode, struct file *file)
2750 if (tracing_disabled)
2752 return single_open(file, tracing_trace_options_show, NULL);
2755 static const struct file_operations tracing_iter_fops = {
2756 .open = tracing_trace_options_open,
2758 .llseek = seq_lseek,
2759 .release = single_release,
2760 .write = tracing_trace_options_write,
2763 static const char readme_msg[] =
2764 "tracing mini-HOWTO:\n\n"
2765 "# mount -t debugfs nodev /sys/kernel/debug\n\n"
2766 "# cat /sys/kernel/debug/tracing/available_tracers\n"
2767 "wakeup preemptirqsoff preemptoff irqsoff function sched_switch nop\n\n"
2768 "# cat /sys/kernel/debug/tracing/current_tracer\n"
2770 "# echo sched_switch > /sys/kernel/debug/tracing/current_tracer\n"
2771 "# cat /sys/kernel/debug/tracing/current_tracer\n"
2773 "# cat /sys/kernel/debug/tracing/trace_options\n"
2774 "noprint-parent nosym-offset nosym-addr noverbose\n"
2775 "# echo print-parent > /sys/kernel/debug/tracing/trace_options\n"
2776 "# echo 1 > /sys/kernel/debug/tracing/tracing_on\n"
2777 "# cat /sys/kernel/debug/tracing/trace > /tmp/trace.txt\n"
2778 "# echo 0 > /sys/kernel/debug/tracing/tracing_on\n"
2782 tracing_readme_read(struct file *filp, char __user *ubuf,
2783 size_t cnt, loff_t *ppos)
2785 return simple_read_from_buffer(ubuf, cnt, ppos,
2786 readme_msg, strlen(readme_msg));
2789 static const struct file_operations tracing_readme_fops = {
2790 .open = tracing_open_generic,
2791 .read = tracing_readme_read,
2792 .llseek = generic_file_llseek,
2796 tracing_saved_cmdlines_read(struct file *file, char __user *ubuf,
2797 size_t cnt, loff_t *ppos)
2806 file_buf = kmalloc(SAVED_CMDLINES*(16+TASK_COMM_LEN), GFP_KERNEL);
2810 buf_comm = kmalloc(TASK_COMM_LEN, GFP_KERNEL);
2818 for (i = 0; i < SAVED_CMDLINES; i++) {
2821 pid = map_cmdline_to_pid[i];
2822 if (pid == -1 || pid == NO_CMDLINE_MAP)
2825 trace_find_cmdline(pid, buf_comm);
2826 r = sprintf(buf, "%d %s\n", pid, buf_comm);
2831 len = simple_read_from_buffer(ubuf, cnt, ppos,
2840 static const struct file_operations tracing_saved_cmdlines_fops = {
2841 .open = tracing_open_generic,
2842 .read = tracing_saved_cmdlines_read,
2843 .llseek = generic_file_llseek,
2847 tracing_ctrl_read(struct file *filp, char __user *ubuf,
2848 size_t cnt, loff_t *ppos)
2853 r = sprintf(buf, "%u\n", tracer_enabled);
2854 return simple_read_from_buffer(ubuf, cnt, ppos, buf, r);
2858 tracing_ctrl_write(struct file *filp, const char __user *ubuf,
2859 size_t cnt, loff_t *ppos)
2861 struct trace_array *tr = filp->private_data;
2865 ret = kstrtoul_from_user(ubuf, cnt, 10, &val);
2871 mutex_lock(&trace_types_lock);
2872 if (tracer_enabled ^ val) {
2874 /* Only need to warn if this is used to change the state */
2875 WARN_ONCE(1, "tracing_enabled is deprecated. Use tracing_on");
2879 if (current_trace->start)
2880 current_trace->start(tr);
2885 if (current_trace->stop)
2886 current_trace->stop(tr);
2889 mutex_unlock(&trace_types_lock);
2897 tracing_set_trace_read(struct file *filp, char __user *ubuf,
2898 size_t cnt, loff_t *ppos)
2900 char buf[MAX_TRACER_SIZE+2];
2903 mutex_lock(&trace_types_lock);
2905 r = sprintf(buf, "%s\n", current_trace->name);
2907 r = sprintf(buf, "\n");
2908 mutex_unlock(&trace_types_lock);
2910 return simple_read_from_buffer(ubuf, cnt, ppos, buf, r);
2913 int tracer_init(struct tracer *t, struct trace_array *tr)
2915 tracing_reset_online_cpus(tr);
2919 static int __tracing_resize_ring_buffer(unsigned long size)
2924 * If kernel or user changes the size of the ring buffer
2925 * we use the size that was given, and we can forget about
2926 * expanding it later.
2928 ring_buffer_expanded = 1;
2930 ret = ring_buffer_resize(global_trace.buffer, size);
2934 if (!current_trace->use_max_tr)
2937 ret = ring_buffer_resize(max_tr.buffer, size);
2941 r = ring_buffer_resize(global_trace.buffer,
2942 global_trace.entries);
2945 * AARGH! We are left with different
2946 * size max buffer!!!!
2947 * The max buffer is our "snapshot" buffer.
2948 * When a tracer needs a snapshot (one of the
2949 * latency tracers), it swaps the max buffer
2950 * with the saved snap shot. We succeeded to
2951 * update the size of the main buffer, but failed to
2952 * update the size of the max buffer. But when we tried
2953 * to reset the main buffer to the original size, we
2954 * failed there too. This is very unlikely to
2955 * happen, but if it does, warn and kill all
2959 tracing_disabled = 1;
2964 max_tr.entries = size;
2966 global_trace.entries = size;
2971 static ssize_t tracing_resize_ring_buffer(unsigned long size)
2973 int cpu, ret = size;
2975 mutex_lock(&trace_types_lock);
2979 /* disable all cpu buffers */
2980 for_each_tracing_cpu(cpu) {
2981 if (global_trace.data[cpu])
2982 atomic_inc(&global_trace.data[cpu]->disabled);
2983 if (max_tr.data[cpu])
2984 atomic_inc(&max_tr.data[cpu]->disabled);
2987 if (size != global_trace.entries)
2988 ret = __tracing_resize_ring_buffer(size);
2993 for_each_tracing_cpu(cpu) {
2994 if (global_trace.data[cpu])
2995 atomic_dec(&global_trace.data[cpu]->disabled);
2996 if (max_tr.data[cpu])
2997 atomic_dec(&max_tr.data[cpu]->disabled);
3001 mutex_unlock(&trace_types_lock);
3008 * tracing_update_buffers - used by tracing facility to expand ring buffers
3010 * To save on memory when the tracing is never used on a system with it
3011 * configured in. The ring buffers are set to a minimum size. But once
3012 * a user starts to use the tracing facility, then they need to grow
3013 * to their default size.
3015 * This function is to be called when a tracer is about to be used.
3017 int tracing_update_buffers(void)
3021 mutex_lock(&trace_types_lock);
3022 if (!ring_buffer_expanded)
3023 ret = __tracing_resize_ring_buffer(trace_buf_size);
3024 mutex_unlock(&trace_types_lock);
3029 struct trace_option_dentry;
3031 static struct trace_option_dentry *
3032 create_trace_option_files(struct tracer *tracer);
3035 destroy_trace_option_files(struct trace_option_dentry *topts);
3037 static int tracing_set_tracer(const char *buf)
3039 static struct trace_option_dentry *topts;
3040 struct trace_array *tr = &global_trace;
3044 mutex_lock(&trace_types_lock);
3046 if (!ring_buffer_expanded) {
3047 ret = __tracing_resize_ring_buffer(trace_buf_size);
3053 for (t = trace_types; t; t = t->next) {
3054 if (strcmp(t->name, buf) == 0)
3061 if (t == current_trace)
3064 trace_branch_disable();
3065 if (current_trace && current_trace->reset)
3066 current_trace->reset(tr);
3067 if (current_trace && current_trace->use_max_tr) {
3069 * We don't free the ring buffer. instead, resize it because
3070 * The max_tr ring buffer has some state (e.g. ring->clock) and
3071 * we want preserve it.
3073 ring_buffer_resize(max_tr.buffer, 1);
3076 destroy_trace_option_files(topts);
3080 topts = create_trace_option_files(current_trace);
3081 if (current_trace->use_max_tr) {
3082 ret = ring_buffer_resize(max_tr.buffer, global_trace.entries);
3085 max_tr.entries = global_trace.entries;
3089 ret = tracer_init(t, tr);
3094 trace_branch_enable(tr);
3096 mutex_unlock(&trace_types_lock);
3102 tracing_set_trace_write(struct file *filp, const char __user *ubuf,
3103 size_t cnt, loff_t *ppos)
3105 char buf[MAX_TRACER_SIZE+1];
3112 if (cnt > MAX_TRACER_SIZE)
3113 cnt = MAX_TRACER_SIZE;
3115 if (copy_from_user(&buf, ubuf, cnt))
3120 /* strip ending whitespace. */
3121 for (i = cnt - 1; i > 0 && isspace(buf[i]); i--)
3124 err = tracing_set_tracer(buf);
3134 tracing_max_lat_read(struct file *filp, char __user *ubuf,
3135 size_t cnt, loff_t *ppos)
3137 unsigned long *ptr = filp->private_data;
3141 r = snprintf(buf, sizeof(buf), "%ld\n",
3142 *ptr == (unsigned long)-1 ? -1 : nsecs_to_usecs(*ptr));
3143 if (r > sizeof(buf))
3145 return simple_read_from_buffer(ubuf, cnt, ppos, buf, r);
3149 tracing_max_lat_write(struct file *filp, const char __user *ubuf,
3150 size_t cnt, loff_t *ppos)
3152 unsigned long *ptr = filp->private_data;
3156 ret = kstrtoul_from_user(ubuf, cnt, 10, &val);
3165 static int tracing_open_pipe(struct inode *inode, struct file *filp)
3167 long cpu_file = (long) inode->i_private;
3168 struct trace_iterator *iter;
3171 if (tracing_disabled)
3174 mutex_lock(&trace_types_lock);
3176 /* create a buffer to store the information to pass to userspace */
3177 iter = kzalloc(sizeof(*iter), GFP_KERNEL);
3184 * We make a copy of the current tracer to avoid concurrent
3185 * changes on it while we are reading.
3187 iter->trace = kmalloc(sizeof(*iter->trace), GFP_KERNEL);
3193 *iter->trace = *current_trace;
3195 if (!alloc_cpumask_var(&iter->started, GFP_KERNEL)) {
3200 /* trace pipe does not show start of buffer */
3201 cpumask_setall(iter->started);
3203 if (trace_flags & TRACE_ITER_LATENCY_FMT)
3204 iter->iter_flags |= TRACE_FILE_LAT_FMT;
3206 iter->cpu_file = cpu_file;
3207 iter->tr = &global_trace;
3208 mutex_init(&iter->mutex);
3209 filp->private_data = iter;
3211 if (iter->trace->pipe_open)
3212 iter->trace->pipe_open(iter);
3214 nonseekable_open(inode, filp);
3216 mutex_unlock(&trace_types_lock);
3222 mutex_unlock(&trace_types_lock);
3226 static int tracing_release_pipe(struct inode *inode, struct file *file)
3228 struct trace_iterator *iter = file->private_data;
3230 mutex_lock(&trace_types_lock);
3232 if (iter->trace->pipe_close)
3233 iter->trace->pipe_close(iter);
3235 mutex_unlock(&trace_types_lock);
3237 free_cpumask_var(iter->started);
3238 mutex_destroy(&iter->mutex);
3246 tracing_poll_pipe(struct file *filp, poll_table *poll_table)
3248 struct trace_iterator *iter = filp->private_data;
3250 if (trace_flags & TRACE_ITER_BLOCK) {
3252 * Always select as readable when in blocking mode
3254 return POLLIN | POLLRDNORM;
3256 if (!trace_empty(iter))
3257 return POLLIN | POLLRDNORM;
3258 poll_wait(filp, &trace_wait, poll_table);
3259 if (!trace_empty(iter))
3260 return POLLIN | POLLRDNORM;
3267 void default_wait_pipe(struct trace_iterator *iter)
3271 prepare_to_wait(&trace_wait, &wait, TASK_INTERRUPTIBLE);
3273 if (trace_empty(iter))
3276 finish_wait(&trace_wait, &wait);
3280 * This is a make-shift waitqueue.
3281 * A tracer might use this callback on some rare cases:
3283 * 1) the current tracer might hold the runqueue lock when it wakes up
3284 * a reader, hence a deadlock (sched, function, and function graph tracers)
3285 * 2) the function tracers, trace all functions, we don't want
3286 * the overhead of calling wake_up and friends
3287 * (and tracing them too)
3289 * Anyway, this is really very primitive wakeup.
3291 void poll_wait_pipe(struct trace_iterator *iter)
3293 set_current_state(TASK_INTERRUPTIBLE);
3294 /* sleep for 100 msecs, and try again. */
3295 schedule_timeout(HZ / 10);
3298 /* Must be called with trace_types_lock mutex held. */
3299 static int tracing_wait_pipe(struct file *filp)
3301 struct trace_iterator *iter = filp->private_data;
3303 while (trace_empty(iter)) {
3305 if ((filp->f_flags & O_NONBLOCK)) {
3309 mutex_unlock(&iter->mutex);
3311 iter->trace->wait_pipe(iter);
3313 mutex_lock(&iter->mutex);
3315 if (signal_pending(current))
3319 * We block until we read something and tracing is disabled.
3320 * We still block if tracing is disabled, but we have never
3321 * read anything. This allows a user to cat this file, and
3322 * then enable tracing. But after we have read something,
3323 * we give an EOF when tracing is again disabled.
3325 * iter->pos will be 0 if we haven't read anything.
3327 if (!tracer_enabled && iter->pos)
3338 tracing_read_pipe(struct file *filp, char __user *ubuf,
3339 size_t cnt, loff_t *ppos)
3341 struct trace_iterator *iter = filp->private_data;
3342 static struct tracer *old_tracer;
3345 /* return any leftover data */
3346 sret = trace_seq_to_user(&iter->seq, ubuf, cnt);
3350 trace_seq_init(&iter->seq);
3352 /* copy the tracer to avoid using a global lock all around */
3353 mutex_lock(&trace_types_lock);
3354 if (unlikely(old_tracer != current_trace && current_trace)) {
3355 old_tracer = current_trace;
3356 *iter->trace = *current_trace;
3358 mutex_unlock(&trace_types_lock);
3361 * Avoid more than one consumer on a single file descriptor
3362 * This is just a matter of traces coherency, the ring buffer itself
3365 mutex_lock(&iter->mutex);
3366 if (iter->trace->read) {
3367 sret = iter->trace->read(iter, filp, ubuf, cnt, ppos);
3373 sret = tracing_wait_pipe(filp);
3377 /* stop when tracing is finished */
3378 if (trace_empty(iter)) {
3383 if (cnt >= PAGE_SIZE)
3384 cnt = PAGE_SIZE - 1;
3386 /* reset all but tr, trace, and overruns */
3387 memset(&iter->seq, 0,
3388 sizeof(struct trace_iterator) -
3389 offsetof(struct trace_iterator, seq));
3392 trace_event_read_lock();
3393 trace_access_lock(iter->cpu_file);
3394 while (trace_find_next_entry_inc(iter) != NULL) {
3395 enum print_line_t ret;
3396 int len = iter->seq.len;
3398 ret = print_trace_line(iter);
3399 if (ret == TRACE_TYPE_PARTIAL_LINE) {
3400 /* don't print partial lines */
3401 iter->seq.len = len;
3404 if (ret != TRACE_TYPE_NO_CONSUME)
3405 trace_consume(iter);
3407 if (iter->seq.len >= cnt)
3411 * Setting the full flag means we reached the trace_seq buffer
3412 * size and we should leave by partial output condition above.
3413 * One of the trace_seq_* functions is not used properly.
3415 WARN_ONCE(iter->seq.full, "full flag set for trace type %d",
3418 trace_access_unlock(iter->cpu_file);
3419 trace_event_read_unlock();
3421 /* Now copy what we have to the user */
3422 sret = trace_seq_to_user(&iter->seq, ubuf, cnt);
3423 if (iter->seq.readpos >= iter->seq.len)
3424 trace_seq_init(&iter->seq);
3427 * If there was nothing to send to user, in spite of consuming trace
3428 * entries, go back to wait for more entries.
3434 mutex_unlock(&iter->mutex);
3439 static void tracing_pipe_buf_release(struct pipe_inode_info *pipe,
3440 struct pipe_buffer *buf)
3442 __free_page(buf->page);
3445 static void tracing_spd_release_pipe(struct splice_pipe_desc *spd,
3448 __free_page(spd->pages[idx]);
3451 static const struct pipe_buf_operations tracing_pipe_buf_ops = {
3453 .map = generic_pipe_buf_map,
3454 .unmap = generic_pipe_buf_unmap,
3455 .confirm = generic_pipe_buf_confirm,
3456 .release = tracing_pipe_buf_release,
3457 .steal = generic_pipe_buf_steal,
3458 .get = generic_pipe_buf_get,
3462 tracing_fill_pipe_page(size_t rem, struct trace_iterator *iter)
3467 /* Seq buffer is page-sized, exactly what we need. */
3469 count = iter->seq.len;
3470 ret = print_trace_line(iter);
3471 count = iter->seq.len - count;
3474 iter->seq.len -= count;
3477 if (ret == TRACE_TYPE_PARTIAL_LINE) {
3478 iter->seq.len -= count;
3482 if (ret != TRACE_TYPE_NO_CONSUME)
3483 trace_consume(iter);
3485 if (!trace_find_next_entry_inc(iter)) {
3495 static ssize_t tracing_splice_read_pipe(struct file *filp,
3497 struct pipe_inode_info *pipe,
3501 struct page *pages_def[PIPE_DEF_BUFFERS];
3502 struct partial_page partial_def[PIPE_DEF_BUFFERS];
3503 struct trace_iterator *iter = filp->private_data;
3504 struct splice_pipe_desc spd = {
3506 .partial = partial_def,
3507 .nr_pages = 0, /* This gets updated below. */
3509 .ops = &tracing_pipe_buf_ops,
3510 .spd_release = tracing_spd_release_pipe,
3512 static struct tracer *old_tracer;
3517 if (splice_grow_spd(pipe, &spd))
3520 /* copy the tracer to avoid using a global lock all around */
3521 mutex_lock(&trace_types_lock);
3522 if (unlikely(old_tracer != current_trace && current_trace)) {
3523 old_tracer = current_trace;
3524 *iter->trace = *current_trace;
3526 mutex_unlock(&trace_types_lock);
3528 mutex_lock(&iter->mutex);
3530 if (iter->trace->splice_read) {
3531 ret = iter->trace->splice_read(iter, filp,
3532 ppos, pipe, len, flags);
3537 ret = tracing_wait_pipe(filp);
3541 if (!iter->ent && !trace_find_next_entry_inc(iter)) {
3546 trace_event_read_lock();
3547 trace_access_lock(iter->cpu_file);
3549 /* Fill as many pages as possible. */
3550 for (i = 0, rem = len; i < pipe->buffers && rem; i++) {
3551 spd.pages[i] = alloc_page(GFP_KERNEL);
3555 rem = tracing_fill_pipe_page(rem, iter);
3557 /* Copy the data into the page, so we can start over. */
3558 ret = trace_seq_to_buffer(&iter->seq,
3559 page_address(spd.pages[i]),
3562 __free_page(spd.pages[i]);
3565 spd.partial[i].offset = 0;
3566 spd.partial[i].len = iter->seq.len;
3568 trace_seq_init(&iter->seq);
3571 trace_access_unlock(iter->cpu_file);
3572 trace_event_read_unlock();
3573 mutex_unlock(&iter->mutex);
3577 ret = splice_to_pipe(pipe, &spd);
3579 splice_shrink_spd(pipe, &spd);
3583 mutex_unlock(&iter->mutex);
3588 tracing_entries_read(struct file *filp, char __user *ubuf,
3589 size_t cnt, loff_t *ppos)
3591 struct trace_array *tr = filp->private_data;
3595 mutex_lock(&trace_types_lock);
3596 if (!ring_buffer_expanded)
3597 r = sprintf(buf, "%lu (expanded: %lu)\n",
3599 trace_buf_size >> 10);
3601 r = sprintf(buf, "%lu\n", tr->entries >> 10);
3602 mutex_unlock(&trace_types_lock);
3604 return simple_read_from_buffer(ubuf, cnt, ppos, buf, r);
3608 tracing_entries_write(struct file *filp, const char __user *ubuf,
3609 size_t cnt, loff_t *ppos)
3614 ret = kstrtoul_from_user(ubuf, cnt, 10, &val);
3618 /* must have at least 1 entry */
3622 /* value is in KB */
3625 ret = tracing_resize_ring_buffer(val);
3635 tracing_total_entries_read(struct file *filp, char __user *ubuf,
3636 size_t cnt, loff_t *ppos)
3638 struct trace_array *tr = filp->private_data;
3641 unsigned long size = 0, expanded_size = 0;
3643 mutex_lock(&trace_types_lock);
3644 for_each_tracing_cpu(cpu) {
3645 size += tr->entries >> 10;
3646 if (!ring_buffer_expanded)
3647 expanded_size += trace_buf_size >> 10;
3649 if (ring_buffer_expanded)
3650 r = sprintf(buf, "%lu\n", size);
3652 r = sprintf(buf, "%lu (expanded: %lu)\n", size, expanded_size);
3653 mutex_unlock(&trace_types_lock);
3655 return simple_read_from_buffer(ubuf, cnt, ppos, buf, r);
3659 tracing_free_buffer_write(struct file *filp, const char __user *ubuf,
3660 size_t cnt, loff_t *ppos)
3663 * There is no need to read what the user has written, this function
3664 * is just to make sure that there is no error when "echo" is used
3673 tracing_free_buffer_release(struct inode *inode, struct file *filp)
3675 /* disable tracing ? */
3676 if (trace_flags & TRACE_ITER_STOP_ON_FREE)
3678 /* resize the ring buffer to 0 */
3679 tracing_resize_ring_buffer(0);
3685 tracing_mark_write(struct file *filp, const char __user *ubuf,
3686 size_t cnt, loff_t *fpos)
3688 unsigned long addr = (unsigned long)ubuf;
3689 struct ring_buffer_event *event;
3690 struct ring_buffer *buffer;
3691 struct print_entry *entry;
3692 unsigned long irq_flags;
3693 struct page *pages[2];
3703 if (tracing_disabled)
3706 if (cnt > TRACE_BUF_SIZE)
3707 cnt = TRACE_BUF_SIZE;
3710 * Userspace is injecting traces into the kernel trace buffer.
3711 * We want to be as non intrusive as possible.
3712 * To do so, we do not want to allocate any special buffers
3713 * or take any locks, but instead write the userspace data
3714 * straight into the ring buffer.
3716 * First we need to pin the userspace buffer into memory,
3717 * which, most likely it is, because it just referenced it.
3718 * But there's no guarantee that it is. By using get_user_pages_fast()
3719 * and kmap_atomic/kunmap_atomic() we can get access to the
3720 * pages directly. We then write the data directly into the
3723 BUILD_BUG_ON(TRACE_BUF_SIZE >= PAGE_SIZE);
3725 /* check if we cross pages */
3726 if ((addr & PAGE_MASK) != ((addr + cnt) & PAGE_MASK))
3729 offset = addr & (PAGE_SIZE - 1);
3732 ret = get_user_pages_fast(addr, nr_pages, 0, pages);
3733 if (ret < nr_pages) {
3735 put_page(pages[ret]);
3740 page1 = kmap_atomic(pages[0]);
3742 page2 = kmap_atomic(pages[1]);
3744 local_save_flags(irq_flags);
3745 size = sizeof(*entry) + cnt + 2; /* possible \n added */
3746 buffer = global_trace.buffer;
3747 event = trace_buffer_lock_reserve(buffer, TRACE_PRINT, size,
3748 irq_flags, preempt_count());
3750 /* Ring buffer disabled, return as if not open for write */
3755 entry = ring_buffer_event_data(event);
3756 entry->ip = _THIS_IP_;
3758 if (nr_pages == 2) {
3759 len = PAGE_SIZE - offset;
3760 memcpy(&entry->buf, page1 + offset, len);
3761 memcpy(&entry->buf[len], page2, cnt - len);
3763 memcpy(&entry->buf, page1 + offset, cnt);
3765 if (entry->buf[cnt - 1] != '\n') {
3766 entry->buf[cnt] = '\n';
3767 entry->buf[cnt + 1] = '\0';
3769 entry->buf[cnt] = '\0';
3771 ring_buffer_unlock_commit(buffer, event);
3779 kunmap_atomic(page2);
3780 kunmap_atomic(page1);
3781 while (nr_pages > 0)
3782 put_page(pages[--nr_pages]);
3787 static int tracing_clock_show(struct seq_file *m, void *v)
3791 for (i = 0; i < ARRAY_SIZE(trace_clocks); i++)
3793 "%s%s%s%s", i ? " " : "",
3794 i == trace_clock_id ? "[" : "", trace_clocks[i].name,
3795 i == trace_clock_id ? "]" : "");
3801 static ssize_t tracing_clock_write(struct file *filp, const char __user *ubuf,
3802 size_t cnt, loff_t *fpos)
3805 const char *clockstr;
3808 if (cnt >= sizeof(buf))
3811 if (copy_from_user(&buf, ubuf, cnt))
3816 clockstr = strstrip(buf);
3818 for (i = 0; i < ARRAY_SIZE(trace_clocks); i++) {
3819 if (strcmp(trace_clocks[i].name, clockstr) == 0)
3822 if (i == ARRAY_SIZE(trace_clocks))
3827 mutex_lock(&trace_types_lock);
3829 ring_buffer_set_clock(global_trace.buffer, trace_clocks[i].func);
3831 ring_buffer_set_clock(max_tr.buffer, trace_clocks[i].func);
3833 mutex_unlock(&trace_types_lock);
3840 static int tracing_clock_open(struct inode *inode, struct file *file)
3842 if (tracing_disabled)
3844 return single_open(file, tracing_clock_show, NULL);
3847 static const struct file_operations tracing_max_lat_fops = {
3848 .open = tracing_open_generic,
3849 .read = tracing_max_lat_read,
3850 .write = tracing_max_lat_write,
3851 .llseek = generic_file_llseek,
3854 static const struct file_operations tracing_ctrl_fops = {
3855 .open = tracing_open_generic,
3856 .read = tracing_ctrl_read,
3857 .write = tracing_ctrl_write,
3858 .llseek = generic_file_llseek,
3861 static const struct file_operations set_tracer_fops = {
3862 .open = tracing_open_generic,
3863 .read = tracing_set_trace_read,
3864 .write = tracing_set_trace_write,
3865 .llseek = generic_file_llseek,
3868 static const struct file_operations tracing_pipe_fops = {
3869 .open = tracing_open_pipe,
3870 .poll = tracing_poll_pipe,
3871 .read = tracing_read_pipe,
3872 .splice_read = tracing_splice_read_pipe,
3873 .release = tracing_release_pipe,
3874 .llseek = no_llseek,
3877 static const struct file_operations tracing_entries_fops = {
3878 .open = tracing_open_generic,
3879 .read = tracing_entries_read,
3880 .write = tracing_entries_write,
3881 .llseek = generic_file_llseek,
3884 static const struct file_operations tracing_total_entries_fops = {
3885 .open = tracing_open_generic,
3886 .read = tracing_total_entries_read,
3887 .llseek = generic_file_llseek,
3890 static const struct file_operations tracing_free_buffer_fops = {
3891 .write = tracing_free_buffer_write,
3892 .release = tracing_free_buffer_release,
3895 static const struct file_operations tracing_mark_fops = {
3896 .open = tracing_open_generic,
3897 .write = tracing_mark_write,
3898 .llseek = generic_file_llseek,
3901 static const struct file_operations trace_clock_fops = {
3902 .open = tracing_clock_open,
3904 .llseek = seq_lseek,
3905 .release = single_release,
3906 .write = tracing_clock_write,
3909 struct ftrace_buffer_info {
3910 struct trace_array *tr;
3916 static int tracing_buffers_open(struct inode *inode, struct file *filp)
3918 int cpu = (int)(long)inode->i_private;
3919 struct ftrace_buffer_info *info;
3921 if (tracing_disabled)
3924 info = kzalloc(sizeof(*info), GFP_KERNEL);
3928 info->tr = &global_trace;
3931 /* Force reading ring buffer for first read */
3932 info->read = (unsigned int)-1;
3934 filp->private_data = info;
3936 return nonseekable_open(inode, filp);
3940 tracing_buffers_read(struct file *filp, char __user *ubuf,
3941 size_t count, loff_t *ppos)
3943 struct ftrace_buffer_info *info = filp->private_data;
3951 info->spare = ring_buffer_alloc_read_page(info->tr->buffer, info->cpu);
3955 /* Do we have previous read data to read? */
3956 if (info->read < PAGE_SIZE)
3959 trace_access_lock(info->cpu);
3960 ret = ring_buffer_read_page(info->tr->buffer,
3964 trace_access_unlock(info->cpu);
3971 size = PAGE_SIZE - info->read;
3975 ret = copy_to_user(ubuf, info->spare + info->read, size);
3986 static int tracing_buffers_release(struct inode *inode, struct file *file)
3988 struct ftrace_buffer_info *info = file->private_data;
3991 ring_buffer_free_read_page(info->tr->buffer, info->spare);
3998 struct ring_buffer *buffer;
4003 static void buffer_pipe_buf_release(struct pipe_inode_info *pipe,
4004 struct pipe_buffer *buf)
4006 struct buffer_ref *ref = (struct buffer_ref *)buf->private;
4011 ring_buffer_free_read_page(ref->buffer, ref->page);
4016 static int buffer_pipe_buf_steal(struct pipe_inode_info *pipe,
4017 struct pipe_buffer *buf)
4022 static void buffer_pipe_buf_get(struct pipe_inode_info *pipe,
4023 struct pipe_buffer *buf)
4025 struct buffer_ref *ref = (struct buffer_ref *)buf->private;
4030 /* Pipe buffer operations for a buffer. */
4031 static const struct pipe_buf_operations buffer_pipe_buf_ops = {
4033 .map = generic_pipe_buf_map,
4034 .unmap = generic_pipe_buf_unmap,
4035 .confirm = generic_pipe_buf_confirm,
4036 .release = buffer_pipe_buf_release,
4037 .steal = buffer_pipe_buf_steal,
4038 .get = buffer_pipe_buf_get,
4042 * Callback from splice_to_pipe(), if we need to release some pages
4043 * at the end of the spd in case we error'ed out in filling the pipe.
4045 static void buffer_spd_release(struct splice_pipe_desc *spd, unsigned int i)
4047 struct buffer_ref *ref =
4048 (struct buffer_ref *)spd->partial[i].private;
4053 ring_buffer_free_read_page(ref->buffer, ref->page);
4055 spd->partial[i].private = 0;
4059 tracing_buffers_splice_read(struct file *file, loff_t *ppos,
4060 struct pipe_inode_info *pipe, size_t len,
4063 struct ftrace_buffer_info *info = file->private_data;
4064 struct partial_page partial_def[PIPE_DEF_BUFFERS];
4065 struct page *pages_def[PIPE_DEF_BUFFERS];
4066 struct splice_pipe_desc spd = {
4068 .partial = partial_def,
4070 .ops = &buffer_pipe_buf_ops,
4071 .spd_release = buffer_spd_release,
4073 struct buffer_ref *ref;
4074 int entries, size, i;
4077 if (splice_grow_spd(pipe, &spd))
4080 if (*ppos & (PAGE_SIZE - 1)) {
4081 WARN_ONCE(1, "Ftrace: previous read must page-align\n");
4086 if (len & (PAGE_SIZE - 1)) {
4087 WARN_ONCE(1, "Ftrace: splice_read should page-align\n");
4088 if (len < PAGE_SIZE) {
4095 trace_access_lock(info->cpu);
4096 entries = ring_buffer_entries_cpu(info->tr->buffer, info->cpu);
4098 for (i = 0; i < pipe->buffers && len && entries; i++, len -= PAGE_SIZE) {
4102 ref = kzalloc(sizeof(*ref), GFP_KERNEL);
4107 ref->buffer = info->tr->buffer;
4108 ref->page = ring_buffer_alloc_read_page(ref->buffer, info->cpu);
4114 r = ring_buffer_read_page(ref->buffer, &ref->page,
4117 ring_buffer_free_read_page(ref->buffer, ref->page);
4123 * zero out any left over data, this is going to
4126 size = ring_buffer_page_len(ref->page);
4127 if (size < PAGE_SIZE)
4128 memset(ref->page + size, 0, PAGE_SIZE - size);
4130 page = virt_to_page(ref->page);
4132 spd.pages[i] = page;
4133 spd.partial[i].len = PAGE_SIZE;
4134 spd.partial[i].offset = 0;
4135 spd.partial[i].private = (unsigned long)ref;
4139 entries = ring_buffer_entries_cpu(info->tr->buffer, info->cpu);
4142 trace_access_unlock(info->cpu);
4145 /* did we read anything? */
4146 if (!spd.nr_pages) {
4147 if (flags & SPLICE_F_NONBLOCK)
4155 ret = splice_to_pipe(pipe, &spd);
4156 splice_shrink_spd(pipe, &spd);
4161 static const struct file_operations tracing_buffers_fops = {
4162 .open = tracing_buffers_open,
4163 .read = tracing_buffers_read,
4164 .release = tracing_buffers_release,
4165 .splice_read = tracing_buffers_splice_read,
4166 .llseek = no_llseek,
4170 tracing_stats_read(struct file *filp, char __user *ubuf,
4171 size_t count, loff_t *ppos)
4173 unsigned long cpu = (unsigned long)filp->private_data;
4174 struct trace_array *tr = &global_trace;
4175 struct trace_seq *s;
4177 unsigned long long t;
4178 unsigned long usec_rem;
4180 s = kmalloc(sizeof(*s), GFP_KERNEL);
4186 cnt = ring_buffer_entries_cpu(tr->buffer, cpu);
4187 trace_seq_printf(s, "entries: %ld\n", cnt);
4189 cnt = ring_buffer_overrun_cpu(tr->buffer, cpu);
4190 trace_seq_printf(s, "overrun: %ld\n", cnt);
4192 cnt = ring_buffer_commit_overrun_cpu(tr->buffer, cpu);
4193 trace_seq_printf(s, "commit overrun: %ld\n", cnt);
4195 cnt = ring_buffer_bytes_cpu(tr->buffer, cpu);
4196 trace_seq_printf(s, "bytes: %ld\n", cnt);
4198 t = ns2usecs(ring_buffer_oldest_event_ts(tr->buffer, cpu));
4199 usec_rem = do_div(t, USEC_PER_SEC);
4200 trace_seq_printf(s, "oldest event ts: %5llu.%06lu\n", t, usec_rem);
4202 t = ns2usecs(ring_buffer_time_stamp(tr->buffer, cpu));
4203 usec_rem = do_div(t, USEC_PER_SEC);
4204 trace_seq_printf(s, "now ts: %5llu.%06lu\n", t, usec_rem);
4206 count = simple_read_from_buffer(ubuf, count, ppos, s->buffer, s->len);
4213 static const struct file_operations tracing_stats_fops = {
4214 .open = tracing_open_generic,
4215 .read = tracing_stats_read,
4216 .llseek = generic_file_llseek,
4219 #ifdef CONFIG_DYNAMIC_FTRACE
4221 int __weak ftrace_arch_read_dyn_info(char *buf, int size)
4227 tracing_read_dyn_info(struct file *filp, char __user *ubuf,
4228 size_t cnt, loff_t *ppos)
4230 static char ftrace_dyn_info_buffer[1024];
4231 static DEFINE_MUTEX(dyn_info_mutex);
4232 unsigned long *p = filp->private_data;
4233 char *buf = ftrace_dyn_info_buffer;
4234 int size = ARRAY_SIZE(ftrace_dyn_info_buffer);
4237 mutex_lock(&dyn_info_mutex);
4238 r = sprintf(buf, "%ld ", *p);
4240 r += ftrace_arch_read_dyn_info(buf+r, (size-1)-r);
4243 r = simple_read_from_buffer(ubuf, cnt, ppos, buf, r);
4245 mutex_unlock(&dyn_info_mutex);
4250 static const struct file_operations tracing_dyn_info_fops = {
4251 .open = tracing_open_generic,
4252 .read = tracing_read_dyn_info,
4253 .llseek = generic_file_llseek,
4257 static struct dentry *d_tracer;
4259 struct dentry *tracing_init_dentry(void)
4266 if (!debugfs_initialized())
4269 d_tracer = debugfs_create_dir("tracing", NULL);
4271 if (!d_tracer && !once) {
4273 pr_warning("Could not create debugfs directory 'tracing'\n");
4280 static struct dentry *d_percpu;
4282 struct dentry *tracing_dentry_percpu(void)
4285 struct dentry *d_tracer;
4290 d_tracer = tracing_init_dentry();
4295 d_percpu = debugfs_create_dir("per_cpu", d_tracer);
4297 if (!d_percpu && !once) {
4299 pr_warning("Could not create debugfs directory 'per_cpu'\n");
4306 static void tracing_init_debugfs_percpu(long cpu)
4308 struct dentry *d_percpu = tracing_dentry_percpu();
4309 struct dentry *d_cpu;
4310 char cpu_dir[30]; /* 30 characters should be more than enough */
4312 snprintf(cpu_dir, 30, "cpu%ld", cpu);
4313 d_cpu = debugfs_create_dir(cpu_dir, d_percpu);
4315 pr_warning("Could not create debugfs '%s' entry\n", cpu_dir);
4319 /* per cpu trace_pipe */
4320 trace_create_file("trace_pipe", 0444, d_cpu,
4321 (void *) cpu, &tracing_pipe_fops);
4324 trace_create_file("trace", 0644, d_cpu,
4325 (void *) cpu, &tracing_fops);
4327 trace_create_file("trace_pipe_raw", 0444, d_cpu,
4328 (void *) cpu, &tracing_buffers_fops);
4330 trace_create_file("stats", 0444, d_cpu,
4331 (void *) cpu, &tracing_stats_fops);
4334 #ifdef CONFIG_FTRACE_SELFTEST
4335 /* Let selftest have access to static functions in this file */
4336 #include "trace_selftest.c"
4339 struct trace_option_dentry {
4340 struct tracer_opt *opt;
4341 struct tracer_flags *flags;
4342 struct dentry *entry;
4346 trace_options_read(struct file *filp, char __user *ubuf, size_t cnt,
4349 struct trace_option_dentry *topt = filp->private_data;
4352 if (topt->flags->val & topt->opt->bit)
4357 return simple_read_from_buffer(ubuf, cnt, ppos, buf, 2);
4361 trace_options_write(struct file *filp, const char __user *ubuf, size_t cnt,
4364 struct trace_option_dentry *topt = filp->private_data;
4368 ret = kstrtoul_from_user(ubuf, cnt, 10, &val);
4372 if (val != 0 && val != 1)
4375 if (!!(topt->flags->val & topt->opt->bit) != val) {
4376 mutex_lock(&trace_types_lock);
4377 ret = __set_tracer_option(current_trace, topt->flags,
4379 mutex_unlock(&trace_types_lock);
4390 static const struct file_operations trace_options_fops = {
4391 .open = tracing_open_generic,
4392 .read = trace_options_read,
4393 .write = trace_options_write,
4394 .llseek = generic_file_llseek,
4398 trace_options_core_read(struct file *filp, char __user *ubuf, size_t cnt,
4401 long index = (long)filp->private_data;
4404 if (trace_flags & (1 << index))
4409 return simple_read_from_buffer(ubuf, cnt, ppos, buf, 2);
4413 trace_options_core_write(struct file *filp, const char __user *ubuf, size_t cnt,
4416 long index = (long)filp->private_data;
4420 ret = kstrtoul_from_user(ubuf, cnt, 10, &val);
4424 if (val != 0 && val != 1)
4426 set_tracer_flags(1 << index, val);
4433 static const struct file_operations trace_options_core_fops = {
4434 .open = tracing_open_generic,
4435 .read = trace_options_core_read,
4436 .write = trace_options_core_write,
4437 .llseek = generic_file_llseek,
4440 struct dentry *trace_create_file(const char *name,
4442 struct dentry *parent,
4444 const struct file_operations *fops)
4448 ret = debugfs_create_file(name, mode, parent, data, fops);
4450 pr_warning("Could not create debugfs '%s' entry\n", name);
4456 static struct dentry *trace_options_init_dentry(void)
4458 struct dentry *d_tracer;
4459 static struct dentry *t_options;
4464 d_tracer = tracing_init_dentry();
4468 t_options = debugfs_create_dir("options", d_tracer);
4470 pr_warning("Could not create debugfs directory 'options'\n");
4478 create_trace_option_file(struct trace_option_dentry *topt,
4479 struct tracer_flags *flags,
4480 struct tracer_opt *opt)
4482 struct dentry *t_options;
4484 t_options = trace_options_init_dentry();
4488 topt->flags = flags;
4491 topt->entry = trace_create_file(opt->name, 0644, t_options, topt,
4492 &trace_options_fops);
4496 static struct trace_option_dentry *
4497 create_trace_option_files(struct tracer *tracer)
4499 struct trace_option_dentry *topts;
4500 struct tracer_flags *flags;
4501 struct tracer_opt *opts;
4507 flags = tracer->flags;
4509 if (!flags || !flags->opts)
4514 for (cnt = 0; opts[cnt].name; cnt++)
4517 topts = kcalloc(cnt + 1, sizeof(*topts), GFP_KERNEL);
4521 for (cnt = 0; opts[cnt].name; cnt++)
4522 create_trace_option_file(&topts[cnt], flags,
4529 destroy_trace_option_files(struct trace_option_dentry *topts)
4536 for (cnt = 0; topts[cnt].opt; cnt++) {
4537 if (topts[cnt].entry)
4538 debugfs_remove(topts[cnt].entry);
4544 static struct dentry *
4545 create_trace_option_core_file(const char *option, long index)
4547 struct dentry *t_options;
4549 t_options = trace_options_init_dentry();
4553 return trace_create_file(option, 0644, t_options, (void *)index,
4554 &trace_options_core_fops);
4557 static __init void create_trace_options_dir(void)
4559 struct dentry *t_options;
4562 t_options = trace_options_init_dentry();
4566 for (i = 0; trace_options[i]; i++)
4567 create_trace_option_core_file(trace_options[i], i);
4570 static __init int tracer_init_debugfs(void)
4572 struct dentry *d_tracer;
4575 trace_access_lock_init();
4577 d_tracer = tracing_init_dentry();
4579 trace_create_file("tracing_enabled", 0644, d_tracer,
4580 &global_trace, &tracing_ctrl_fops);
4582 trace_create_file("trace_options", 0644, d_tracer,
4583 NULL, &tracing_iter_fops);
4585 trace_create_file("tracing_cpumask", 0644, d_tracer,
4586 NULL, &tracing_cpumask_fops);
4588 trace_create_file("trace", 0644, d_tracer,
4589 (void *) TRACE_PIPE_ALL_CPU, &tracing_fops);
4591 trace_create_file("available_tracers", 0444, d_tracer,
4592 &global_trace, &show_traces_fops);
4594 trace_create_file("current_tracer", 0644, d_tracer,
4595 &global_trace, &set_tracer_fops);
4597 #ifdef CONFIG_TRACER_MAX_TRACE
4598 trace_create_file("tracing_max_latency", 0644, d_tracer,
4599 &tracing_max_latency, &tracing_max_lat_fops);
4602 trace_create_file("tracing_thresh", 0644, d_tracer,
4603 &tracing_thresh, &tracing_max_lat_fops);
4605 trace_create_file("README", 0444, d_tracer,
4606 NULL, &tracing_readme_fops);
4608 trace_create_file("trace_pipe", 0444, d_tracer,
4609 (void *) TRACE_PIPE_ALL_CPU, &tracing_pipe_fops);
4611 trace_create_file("buffer_size_kb", 0644, d_tracer,
4612 &global_trace, &tracing_entries_fops);
4614 trace_create_file("buffer_total_size_kb", 0444, d_tracer,
4615 &global_trace, &tracing_total_entries_fops);
4617 trace_create_file("free_buffer", 0644, d_tracer,
4618 &global_trace, &tracing_free_buffer_fops);
4620 trace_create_file("trace_marker", 0220, d_tracer,
4621 NULL, &tracing_mark_fops);
4623 trace_create_file("saved_cmdlines", 0444, d_tracer,
4624 NULL, &tracing_saved_cmdlines_fops);
4626 trace_create_file("trace_clock", 0644, d_tracer, NULL,
4629 #ifdef CONFIG_DYNAMIC_FTRACE
4630 trace_create_file("dyn_ftrace_total_info", 0444, d_tracer,
4631 &ftrace_update_tot_cnt, &tracing_dyn_info_fops);
4634 create_trace_options_dir();
4636 for_each_tracing_cpu(cpu)
4637 tracing_init_debugfs_percpu(cpu);
4642 static int trace_panic_handler(struct notifier_block *this,
4643 unsigned long event, void *unused)
4645 if (ftrace_dump_on_oops)
4646 ftrace_dump(ftrace_dump_on_oops);
4650 static struct notifier_block trace_panic_notifier = {
4651 .notifier_call = trace_panic_handler,
4653 .priority = 150 /* priority: INT_MAX >= x >= 0 */
4656 static int trace_die_handler(struct notifier_block *self,
4662 if (ftrace_dump_on_oops)
4663 ftrace_dump(ftrace_dump_on_oops);
4671 static struct notifier_block trace_die_notifier = {
4672 .notifier_call = trace_die_handler,
4677 * printk is set to max of 1024, we really don't need it that big.
4678 * Nothing should be printing 1000 characters anyway.
4680 #define TRACE_MAX_PRINT 1000
4683 * Define here KERN_TRACE so that we have one place to modify
4684 * it if we decide to change what log level the ftrace dump
4687 #define KERN_TRACE KERN_EMERG
4690 trace_printk_seq(struct trace_seq *s)
4692 /* Probably should print a warning here. */
4696 /* should be zero ended, but we are paranoid. */
4697 s->buffer[s->len] = 0;
4699 printk(KERN_TRACE "%s", s->buffer);
4704 void trace_init_global_iter(struct trace_iterator *iter)
4706 iter->tr = &global_trace;
4707 iter->trace = current_trace;
4708 iter->cpu_file = TRACE_PIPE_ALL_CPU;
4712 __ftrace_dump(bool disable_tracing, enum ftrace_dump_mode oops_dump_mode)
4714 static arch_spinlock_t ftrace_dump_lock =
4715 (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
4716 /* use static because iter can be a bit big for the stack */
4717 static struct trace_iterator iter;
4718 unsigned int old_userobj;
4719 static int dump_ran;
4720 unsigned long flags;
4724 local_irq_save(flags);
4725 arch_spin_lock(&ftrace_dump_lock);
4733 /* Did function tracer already get disabled? */
4734 if (ftrace_is_dead()) {
4735 printk("# WARNING: FUNCTION TRACING IS CORRUPTED\n");
4736 printk("# MAY BE MISSING FUNCTION EVENTS\n");
4739 if (disable_tracing)
4742 trace_init_global_iter(&iter);
4744 for_each_tracing_cpu(cpu) {
4745 atomic_inc(&iter.tr->data[cpu]->disabled);
4748 old_userobj = trace_flags & TRACE_ITER_SYM_USEROBJ;
4750 /* don't look at user memory in panic mode */
4751 trace_flags &= ~TRACE_ITER_SYM_USEROBJ;
4753 /* Simulate the iterator */
4754 iter.tr = &global_trace;
4755 iter.trace = current_trace;
4757 switch (oops_dump_mode) {
4759 iter.cpu_file = TRACE_PIPE_ALL_CPU;
4762 iter.cpu_file = raw_smp_processor_id();
4767 printk(KERN_TRACE "Bad dumping mode, switching to all CPUs dump\n");
4768 iter.cpu_file = TRACE_PIPE_ALL_CPU;
4771 printk(KERN_TRACE "Dumping ftrace buffer:\n");
4774 * We need to stop all tracing on all CPUS to read the
4775 * the next buffer. This is a bit expensive, but is
4776 * not done often. We fill all what we can read,
4777 * and then release the locks again.
4780 while (!trace_empty(&iter)) {
4783 printk(KERN_TRACE "---------------------------------\n");
4787 /* reset all but tr, trace, and overruns */
4788 memset(&iter.seq, 0,
4789 sizeof(struct trace_iterator) -
4790 offsetof(struct trace_iterator, seq));
4791 iter.iter_flags |= TRACE_FILE_LAT_FMT;
4794 if (trace_find_next_entry_inc(&iter) != NULL) {
4797 ret = print_trace_line(&iter);
4798 if (ret != TRACE_TYPE_NO_CONSUME)
4799 trace_consume(&iter);
4802 trace_printk_seq(&iter.seq);
4806 printk(KERN_TRACE " (ftrace buffer empty)\n");
4808 printk(KERN_TRACE "---------------------------------\n");
4811 /* Re-enable tracing if requested */
4812 if (!disable_tracing) {
4813 trace_flags |= old_userobj;
4815 for_each_tracing_cpu(cpu) {
4816 atomic_dec(&iter.tr->data[cpu]->disabled);
4822 arch_spin_unlock(&ftrace_dump_lock);
4823 local_irq_restore(flags);
4826 /* By default: disable tracing after the dump */
4827 void ftrace_dump(enum ftrace_dump_mode oops_dump_mode)
4829 __ftrace_dump(true, oops_dump_mode);
4831 EXPORT_SYMBOL_GPL(ftrace_dump);
4833 __init static int tracer_alloc_buffers(void)
4836 enum ring_buffer_flags rb_flags;
4841 if (!alloc_cpumask_var(&tracing_buffer_mask, GFP_KERNEL))
4844 if (!alloc_cpumask_var(&tracing_cpumask, GFP_KERNEL))
4845 goto out_free_buffer_mask;
4847 /* To save memory, keep the ring buffer size to its minimum */
4848 if (ring_buffer_expanded)
4849 ring_buf_size = trace_buf_size;
4853 rb_flags = trace_flags & TRACE_ITER_OVERWRITE ? RB_FL_OVERWRITE : 0;
4855 cpumask_copy(tracing_buffer_mask, cpu_possible_mask);
4856 cpumask_copy(tracing_cpumask, cpu_all_mask);
4858 /* TODO: make the number of buffers hot pluggable with CPUS */
4859 global_trace.buffer = ring_buffer_alloc(ring_buf_size, rb_flags);
4860 if (!global_trace.buffer) {
4861 printk(KERN_ERR "tracer: failed to allocate ring buffer!\n");
4863 goto out_free_cpumask;
4865 global_trace.entries = ring_buffer_size(global_trace.buffer);
4868 #ifdef CONFIG_TRACER_MAX_TRACE
4869 max_tr.buffer = ring_buffer_alloc(1, rb_flags);
4870 if (!max_tr.buffer) {
4871 printk(KERN_ERR "tracer: failed to allocate max ring buffer!\n");
4873 ring_buffer_free(global_trace.buffer);
4874 goto out_free_cpumask;
4879 /* Allocate the first page for all buffers */
4880 for_each_tracing_cpu(i) {
4881 global_trace.data[i] = &per_cpu(global_trace_cpu, i);
4882 max_tr.data[i] = &per_cpu(max_tr_data, i);
4885 trace_init_cmdlines();
4887 register_tracer(&nop_trace);
4888 current_trace = &nop_trace;
4889 /* All seems OK, enable tracing */
4890 tracing_disabled = 0;
4892 atomic_notifier_chain_register(&panic_notifier_list,
4893 &trace_panic_notifier);
4895 register_die_notifier(&trace_die_notifier);
4900 free_cpumask_var(tracing_cpumask);
4901 out_free_buffer_mask:
4902 free_cpumask_var(tracing_buffer_mask);
4907 __init static int clear_boot_tracer(void)
4910 * The default tracer at boot buffer is an init section.
4911 * This function is called in lateinit. If we did not
4912 * find the boot tracer, then clear it out, to prevent
4913 * later registration from accessing the buffer that is
4914 * about to be freed.
4916 if (!default_bootup_tracer)
4919 printk(KERN_INFO "ftrace bootup tracer '%s' not registered.\n",
4920 default_bootup_tracer);
4921 default_bootup_tracer = NULL;
4926 early_initcall(tracer_alloc_buffers);
4927 fs_initcall(tracer_init_debugfs);
4928 late_initcall(clear_boot_tracer);