tracing: Add support for 'synthetic' events

Synthetic events are user-defined events generated from hist trigger
variables saved from one or more other events.

To define a synthetic event, the user writes a simple specification
consisting of the name of the new event along with one or more
variables and their type(s), to the tracing/synthetic_events file.

For instance, the following creates a new event named 'wakeup_latency'
with 3 fields: lat, pid, and prio:

    # echo 'wakeup_latency u64 lat; pid_t pid; int prio' >> \
      /sys/kernel/debug/tracing/synthetic_events

Reading the tracing/synthetic_events file lists all the
currently-defined synthetic events, in this case the event we defined
above:

    # cat /sys/kernel/debug/tracing/synthetic_events
    wakeup_latency u64 lat; pid_t pid; int prio

At this point, the synthetic event is ready to use, and a histogram
can be defined using it:

    # echo 'hist:keys=pid,prio,lat.log2:sort=pid,lat' >> \
    /sys/kernel/debug/tracing/events/synthetic/wakeup_latency/trigger

The new event is created under the tracing/events/synthetic/ directory
and looks and behaves just like any other event:

    # ls /sys/kernel/debug/tracing/events/synthetic/wakeup_latency
      enable  filter  format  hist  id  trigger

Although a histogram can be defined for it, nothing will happen until
an action tracing that event via the trace_synth() function occurs.
The trace_synth() function is very similar to all the other trace_*
invocations spread throughout the kernel, except in this case the
trace_ function and its corresponding tracepoint isn't statically
generated but defined by the user at run-time.

How this can be automatically hooked up via a hist trigger 'action' is
discussed in a subsequent patch.

Link: http://lkml.kernel.org/r/c68df2284b7d172669daf9be29db62ad49bbc559.1516069914.git.tom.zanussi@linux.intel.com

Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>
[fix noderef.cocci warnings, sizeof pointer for kcalloc of event->fields]
Signed-off-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
This commit is contained in:
Tom Zanussi 2018-01-15 20:51:58 -06:00 committed by Steven Rostedt (VMware)
parent 0212e2aa30
commit 4b147936fa
1 changed files with 893 additions and 2 deletions

View File

@ -20,10 +20,16 @@
#include <linux/slab.h>
#include <linux/stacktrace.h>
#include <linux/rculist.h>
#include <linux/tracefs.h>
#include "tracing_map.h"
#include "trace.h"
#define SYNTH_SYSTEM "synthetic"
#define SYNTH_FIELDS_MAX 16
#define STR_VAR_LEN_MAX 32 /* must be multiple of sizeof(u64) */
struct hist_field;
typedef u64 (*hist_field_fn_t) (struct hist_field *field,
@ -270,6 +276,26 @@ struct hist_trigger_data {
unsigned int n_actions;
};
struct synth_field {
char *type;
char *name;
size_t size;
bool is_signed;
bool is_string;
};
struct synth_event {
struct list_head list;
int ref;
char *name;
struct synth_field **fields;
unsigned int n_fields;
unsigned int n_u64;
struct trace_event_class class;
struct trace_event_call call;
struct tracepoint *tp;
};
struct action_data;
typedef void (*action_fn_t) (struct hist_trigger_data *hist_data,
@ -282,6 +308,790 @@ struct action_data {
unsigned int var_ref_idx;
};
static LIST_HEAD(synth_event_list);
static DEFINE_MUTEX(synth_event_mutex);
struct synth_trace_event {
struct trace_entry ent;
u64 fields[];
};
static int synth_event_define_fields(struct trace_event_call *call)
{
struct synth_trace_event trace;
int offset = offsetof(typeof(trace), fields);
struct synth_event *event = call->data;
unsigned int i, size, n_u64;
char *name, *type;
bool is_signed;
int ret = 0;
for (i = 0, n_u64 = 0; i < event->n_fields; i++) {
size = event->fields[i]->size;
is_signed = event->fields[i]->is_signed;
type = event->fields[i]->type;
name = event->fields[i]->name;
ret = trace_define_field(call, type, name, offset, size,
is_signed, FILTER_OTHER);
if (ret)
break;
if (event->fields[i]->is_string) {
offset += STR_VAR_LEN_MAX;
n_u64 += STR_VAR_LEN_MAX / sizeof(u64);
} else {
offset += sizeof(u64);
n_u64++;
}
}
event->n_u64 = n_u64;
return ret;
}
static bool synth_field_signed(char *type)
{
if (strncmp(type, "u", 1) == 0)
return false;
return true;
}
static int synth_field_is_string(char *type)
{
if (strstr(type, "char[") != NULL)
return true;
return false;
}
static int synth_field_string_size(char *type)
{
char buf[4], *end, *start;
unsigned int len;
int size, err;
start = strstr(type, "char[");
if (start == NULL)
return -EINVAL;
start += strlen("char[");
end = strchr(type, ']');
if (!end || end < start)
return -EINVAL;
len = end - start;
if (len > 3)
return -EINVAL;
strncpy(buf, start, len);
buf[len] = '\0';
err = kstrtouint(buf, 0, &size);
if (err)
return err;
if (size > STR_VAR_LEN_MAX)
return -EINVAL;
return size;
}
static int synth_field_size(char *type)
{
int size = 0;
if (strcmp(type, "s64") == 0)
size = sizeof(s64);
else if (strcmp(type, "u64") == 0)
size = sizeof(u64);
else if (strcmp(type, "s32") == 0)
size = sizeof(s32);
else if (strcmp(type, "u32") == 0)
size = sizeof(u32);
else if (strcmp(type, "s16") == 0)
size = sizeof(s16);
else if (strcmp(type, "u16") == 0)
size = sizeof(u16);
else if (strcmp(type, "s8") == 0)
size = sizeof(s8);
else if (strcmp(type, "u8") == 0)
size = sizeof(u8);
else if (strcmp(type, "char") == 0)
size = sizeof(char);
else if (strcmp(type, "unsigned char") == 0)
size = sizeof(unsigned char);
else if (strcmp(type, "int") == 0)
size = sizeof(int);
else if (strcmp(type, "unsigned int") == 0)
size = sizeof(unsigned int);
else if (strcmp(type, "long") == 0)
size = sizeof(long);
else if (strcmp(type, "unsigned long") == 0)
size = sizeof(unsigned long);
else if (strcmp(type, "pid_t") == 0)
size = sizeof(pid_t);
else if (synth_field_is_string(type))
size = synth_field_string_size(type);
return size;
}
static const char *synth_field_fmt(char *type)
{
const char *fmt = "%llu";
if (strcmp(type, "s64") == 0)
fmt = "%lld";
else if (strcmp(type, "u64") == 0)
fmt = "%llu";
else if (strcmp(type, "s32") == 0)
fmt = "%d";
else if (strcmp(type, "u32") == 0)
fmt = "%u";
else if (strcmp(type, "s16") == 0)
fmt = "%d";
else if (strcmp(type, "u16") == 0)
fmt = "%u";
else if (strcmp(type, "s8") == 0)
fmt = "%d";
else if (strcmp(type, "u8") == 0)
fmt = "%u";
else if (strcmp(type, "char") == 0)
fmt = "%d";
else if (strcmp(type, "unsigned char") == 0)
fmt = "%u";
else if (strcmp(type, "int") == 0)
fmt = "%d";
else if (strcmp(type, "unsigned int") == 0)
fmt = "%u";
else if (strcmp(type, "long") == 0)
fmt = "%ld";
else if (strcmp(type, "unsigned long") == 0)
fmt = "%lu";
else if (strcmp(type, "pid_t") == 0)
fmt = "%d";
else if (synth_field_is_string(type))
fmt = "%s";
return fmt;
}
static enum print_line_t print_synth_event(struct trace_iterator *iter,
int flags,
struct trace_event *event)
{
struct trace_array *tr = iter->tr;
struct trace_seq *s = &iter->seq;
struct synth_trace_event *entry;
struct synth_event *se;
unsigned int i, n_u64;
char print_fmt[32];
const char *fmt;
entry = (struct synth_trace_event *)iter->ent;
se = container_of(event, struct synth_event, call.event);
trace_seq_printf(s, "%s: ", se->name);
for (i = 0, n_u64 = 0; i < se->n_fields; i++) {
if (trace_seq_has_overflowed(s))
goto end;
fmt = synth_field_fmt(se->fields[i]->type);
/* parameter types */
if (tr->trace_flags & TRACE_ITER_VERBOSE)
trace_seq_printf(s, "%s ", fmt);
snprintf(print_fmt, sizeof(print_fmt), "%%s=%s%%s", fmt);
/* parameter values */
if (se->fields[i]->is_string) {
trace_seq_printf(s, print_fmt, se->fields[i]->name,
(char *)&entry->fields[n_u64],
i == se->n_fields - 1 ? "" : " ");
n_u64 += STR_VAR_LEN_MAX / sizeof(u64);
} else {
trace_seq_printf(s, print_fmt, se->fields[i]->name,
entry->fields[n_u64],
i == se->n_fields - 1 ? "" : " ");
n_u64++;
}
}
end:
trace_seq_putc(s, '\n');
return trace_handle_return(s);
}
static struct trace_event_functions synth_event_funcs = {
.trace = print_synth_event
};
static notrace void trace_event_raw_event_synth(void *__data,
u64 *var_ref_vals,
unsigned int var_ref_idx)
{
struct trace_event_file *trace_file = __data;
struct synth_trace_event *entry;
struct trace_event_buffer fbuffer;
struct synth_event *event;
unsigned int i, n_u64;
int fields_size = 0;
event = trace_file->event_call->data;
if (trace_trigger_soft_disabled(trace_file))
return;
fields_size = event->n_u64 * sizeof(u64);
entry = trace_event_buffer_reserve(&fbuffer, trace_file,
sizeof(*entry) + fields_size);
if (!entry)
return;
for (i = 0, n_u64 = 0; i < event->n_fields; i++) {
if (event->fields[i]->is_string) {
char *str_val = (char *)(long)var_ref_vals[var_ref_idx + i];
char *str_field = (char *)&entry->fields[n_u64];
strncpy(str_field, str_val, STR_VAR_LEN_MAX);
n_u64 += STR_VAR_LEN_MAX / sizeof(u64);
} else {
entry->fields[n_u64] = var_ref_vals[var_ref_idx + i];
n_u64++;
}
}
trace_event_buffer_commit(&fbuffer);
}
static void free_synth_event_print_fmt(struct trace_event_call *call)
{
if (call) {
kfree(call->print_fmt);
call->print_fmt = NULL;
}
}
static int __set_synth_event_print_fmt(struct synth_event *event,
char *buf, int len)
{
const char *fmt;
int pos = 0;
int i;
/* When len=0, we just calculate the needed length */
#define LEN_OR_ZERO (len ? len - pos : 0)
pos += snprintf(buf + pos, LEN_OR_ZERO, "\"");
for (i = 0; i < event->n_fields; i++) {
fmt = synth_field_fmt(event->fields[i]->type);
pos += snprintf(buf + pos, LEN_OR_ZERO, "%s=%s%s",
event->fields[i]->name, fmt,
i == event->n_fields - 1 ? "" : ", ");
}
pos += snprintf(buf + pos, LEN_OR_ZERO, "\"");
for (i = 0; i < event->n_fields; i++) {
pos += snprintf(buf + pos, LEN_OR_ZERO,
", REC->%s", event->fields[i]->name);
}
#undef LEN_OR_ZERO
/* return the length of print_fmt */
return pos;
}
static int set_synth_event_print_fmt(struct trace_event_call *call)
{
struct synth_event *event = call->data;
char *print_fmt;
int len;
/* First: called with 0 length to calculate the needed length */
len = __set_synth_event_print_fmt(event, NULL, 0);
print_fmt = kmalloc(len + 1, GFP_KERNEL);
if (!print_fmt)
return -ENOMEM;
/* Second: actually write the @print_fmt */
__set_synth_event_print_fmt(event, print_fmt, len + 1);
call->print_fmt = print_fmt;
return 0;
}
static void free_synth_field(struct synth_field *field)
{
kfree(field->type);
kfree(field->name);
kfree(field);
}
static struct synth_field *parse_synth_field(char *field_type,
char *field_name)
{
struct synth_field *field;
int len, ret = 0;
char *array;
if (field_type[0] == ';')
field_type++;
len = strlen(field_name);
if (field_name[len - 1] == ';')
field_name[len - 1] = '\0';
field = kzalloc(sizeof(*field), GFP_KERNEL);
if (!field)
return ERR_PTR(-ENOMEM);
len = strlen(field_type) + 1;
array = strchr(field_name, '[');
if (array)
len += strlen(array);
field->type = kzalloc(len, GFP_KERNEL);
if (!field->type) {
ret = -ENOMEM;
goto free;
}
strcat(field->type, field_type);
if (array) {
strcat(field->type, array);
*array = '\0';
}
field->size = synth_field_size(field->type);
if (!field->size) {
ret = -EINVAL;
goto free;
}
if (synth_field_is_string(field->type))
field->is_string = true;
field->is_signed = synth_field_signed(field->type);
field->name = kstrdup(field_name, GFP_KERNEL);
if (!field->name) {
ret = -ENOMEM;
goto free;
}
out:
return field;
free:
free_synth_field(field);
field = ERR_PTR(ret);
goto out;
}
static void free_synth_tracepoint(struct tracepoint *tp)
{
if (!tp)
return;
kfree(tp->name);
kfree(tp);
}
static struct tracepoint *alloc_synth_tracepoint(char *name)
{
struct tracepoint *tp;
tp = kzalloc(sizeof(*tp), GFP_KERNEL);
if (!tp)
return ERR_PTR(-ENOMEM);
tp->name = kstrdup(name, GFP_KERNEL);
if (!tp->name) {
kfree(tp);
return ERR_PTR(-ENOMEM);
}
return tp;
}
typedef void (*synth_probe_func_t) (void *__data, u64 *var_ref_vals,
unsigned int var_ref_idx);
static inline void trace_synth(struct synth_event *event, u64 *var_ref_vals,
unsigned int var_ref_idx)
{
struct tracepoint *tp = event->tp;
if (unlikely(atomic_read(&tp->key.enabled) > 0)) {
struct tracepoint_func *probe_func_ptr;
synth_probe_func_t probe_func;
void *__data;
if (!(cpu_online(raw_smp_processor_id())))
return;
probe_func_ptr = rcu_dereference_sched((tp)->funcs);
if (probe_func_ptr) {
do {
probe_func = probe_func_ptr->func;
__data = probe_func_ptr->data;
probe_func(__data, var_ref_vals, var_ref_idx);
} while ((++probe_func_ptr)->func);
}
}
}
static struct synth_event *find_synth_event(const char *name)
{
struct synth_event *event;
list_for_each_entry(event, &synth_event_list, list) {
if (strcmp(event->name, name) == 0)
return event;
}
return NULL;
}
static int register_synth_event(struct synth_event *event)
{
struct trace_event_call *call = &event->call;
int ret = 0;
event->call.class = &event->class;
event->class.system = kstrdup(SYNTH_SYSTEM, GFP_KERNEL);
if (!event->class.system) {
ret = -ENOMEM;
goto out;
}
event->tp = alloc_synth_tracepoint(event->name);
if (IS_ERR(event->tp)) {
ret = PTR_ERR(event->tp);
event->tp = NULL;
goto out;
}
INIT_LIST_HEAD(&call->class->fields);
call->event.funcs = &synth_event_funcs;
call->class->define_fields = synth_event_define_fields;
ret = register_trace_event(&call->event);
if (!ret) {
ret = -ENODEV;
goto out;
}
call->flags = TRACE_EVENT_FL_TRACEPOINT;
call->class->reg = trace_event_reg;
call->class->probe = trace_event_raw_event_synth;
call->data = event;
call->tp = event->tp;
ret = trace_add_event_call(call);
if (ret) {
pr_warn("Failed to register synthetic event: %s\n",
trace_event_name(call));
goto err;
}
ret = set_synth_event_print_fmt(call);
if (ret < 0) {
trace_remove_event_call(call);
goto err;
}
out:
return ret;
err:
unregister_trace_event(&call->event);
goto out;
}
static int unregister_synth_event(struct synth_event *event)
{
struct trace_event_call *call = &event->call;
int ret;
ret = trace_remove_event_call(call);
return ret;
}
static void free_synth_event(struct synth_event *event)
{
unsigned int i;
if (!event)
return;
for (i = 0; i < event->n_fields; i++)
free_synth_field(event->fields[i]);
kfree(event->fields);
kfree(event->name);
kfree(event->class.system);
free_synth_tracepoint(event->tp);
free_synth_event_print_fmt(&event->call);
kfree(event);
}
static struct synth_event *alloc_synth_event(char *event_name, int n_fields,
struct synth_field **fields)
{
struct synth_event *event;
unsigned int i;
event = kzalloc(sizeof(*event), GFP_KERNEL);
if (!event) {
event = ERR_PTR(-ENOMEM);
goto out;
}
event->name = kstrdup(event_name, GFP_KERNEL);
if (!event->name) {
kfree(event);
event = ERR_PTR(-ENOMEM);
goto out;
}
event->fields = kcalloc(n_fields, sizeof(*event->fields), GFP_KERNEL);
if (!event->fields) {
free_synth_event(event);
event = ERR_PTR(-ENOMEM);
goto out;
}
for (i = 0; i < n_fields; i++)
event->fields[i] = fields[i];
event->n_fields = n_fields;
out:
return event;
}
static void add_or_delete_synth_event(struct synth_event *event, int delete)
{
if (delete)
free_synth_event(event);
else {
mutex_lock(&synth_event_mutex);
if (!find_synth_event(event->name))
list_add(&event->list, &synth_event_list);
else
free_synth_event(event);
mutex_unlock(&synth_event_mutex);
}
}
static int create_synth_event(int argc, char **argv)
{
struct synth_field *field, *fields[SYNTH_FIELDS_MAX];
struct synth_event *event = NULL;
bool delete_event = false;
int i, n_fields = 0, ret = 0;
char *name;
mutex_lock(&synth_event_mutex);
/*
* Argument syntax:
* - Add synthetic event: <event_name> field[;field] ...
* - Remove synthetic event: !<event_name> field[;field] ...
* where 'field' = type field_name
*/
if (argc < 1) {
ret = -EINVAL;
goto out;
}
name = argv[0];
if (name[0] == '!') {
delete_event = true;
name++;
}
event = find_synth_event(name);
if (event) {
if (delete_event) {
if (event->ref) {
event = NULL;
ret = -EBUSY;
goto out;
}
list_del(&event->list);
goto out;
}
event = NULL;
ret = -EEXIST;
goto out;
} else if (delete_event)
goto out;
if (argc < 2) {
ret = -EINVAL;
goto out;
}
for (i = 1; i < argc - 1; i++) {
if (strcmp(argv[i], ";") == 0)
continue;
if (n_fields == SYNTH_FIELDS_MAX) {
ret = -EINVAL;
goto err;
}
field = parse_synth_field(argv[i], argv[i + 1]);
if (IS_ERR(field)) {
ret = PTR_ERR(field);
goto err;
}
fields[n_fields] = field;
i++; n_fields++;
}
if (i < argc) {
ret = -EINVAL;
goto err;
}
event = alloc_synth_event(name, n_fields, fields);
if (IS_ERR(event)) {
ret = PTR_ERR(event);
event = NULL;
goto err;
}
out:
mutex_unlock(&synth_event_mutex);
if (event) {
if (delete_event) {
ret = unregister_synth_event(event);
add_or_delete_synth_event(event, !ret);
} else {
ret = register_synth_event(event);
add_or_delete_synth_event(event, ret);
}
}
return ret;
err:
mutex_unlock(&synth_event_mutex);
for (i = 0; i < n_fields; i++)
free_synth_field(fields[i]);
free_synth_event(event);
return ret;
}
static int release_all_synth_events(void)
{
struct list_head release_events;
struct synth_event *event, *e;
int ret = 0;
INIT_LIST_HEAD(&release_events);
mutex_lock(&synth_event_mutex);
list_for_each_entry(event, &synth_event_list, list) {
if (event->ref) {
mutex_unlock(&synth_event_mutex);
return -EBUSY;
}
}
list_splice_init(&event->list, &release_events);
mutex_unlock(&synth_event_mutex);
list_for_each_entry_safe(event, e, &release_events, list) {
list_del(&event->list);
ret = unregister_synth_event(event);
add_or_delete_synth_event(event, !ret);
}
return ret;
}
static void *synth_events_seq_start(struct seq_file *m, loff_t *pos)
{
mutex_lock(&synth_event_mutex);
return seq_list_start(&synth_event_list, *pos);
}
static void *synth_events_seq_next(struct seq_file *m, void *v, loff_t *pos)
{
return seq_list_next(v, &synth_event_list, pos);
}
static void synth_events_seq_stop(struct seq_file *m, void *v)
{
mutex_unlock(&synth_event_mutex);
}
static int synth_events_seq_show(struct seq_file *m, void *v)
{
struct synth_field *field;
struct synth_event *event = v;
unsigned int i;
seq_printf(m, "%s\t", event->name);
for (i = 0; i < event->n_fields; i++) {
field = event->fields[i];
/* parameter values */
seq_printf(m, "%s %s%s", field->type, field->name,
i == event->n_fields - 1 ? "" : "; ");
}
seq_putc(m, '\n');
return 0;
}
static const struct seq_operations synth_events_seq_op = {
.start = synth_events_seq_start,
.next = synth_events_seq_next,
.stop = synth_events_seq_stop,
.show = synth_events_seq_show
};
static int synth_events_open(struct inode *inode, struct file *file)
{
int ret;
if ((file->f_mode & FMODE_WRITE) && (file->f_flags & O_TRUNC)) {
ret = release_all_synth_events();
if (ret < 0)
return ret;
}
return seq_open(file, &synth_events_seq_op);
}
static ssize_t synth_events_write(struct file *file,
const char __user *buffer,
size_t count, loff_t *ppos)
{
return trace_parse_run_command(file, buffer, count, ppos,
create_synth_event);
}
static const struct file_operations synth_events_fops = {
.open = synth_events_open,
.write = synth_events_write,
.read = seq_read,
.llseek = seq_lseek,
.release = seq_release,
};
static u64 hist_field_timestamp(struct hist_field *hist_field,
struct tracing_map_elt *elt,
struct ring_buffer_event *rbe,
@ -2963,6 +3773,28 @@ static int hist_trigger_enable(struct event_trigger_data *data,
return ret;
}
static bool have_hist_trigger_match(struct event_trigger_data *data,
struct trace_event_file *file)
{
struct hist_trigger_data *hist_data = data->private_data;
struct event_trigger_data *test, *named_data = NULL;
bool match = false;
if (hist_data->attrs->name)
named_data = find_named_trigger(hist_data->attrs->name);
list_for_each_entry_rcu(test, &file->triggers, list) {
if (test->cmd_ops->trigger_type == ETT_EVENT_HIST) {
if (hist_trigger_match(data, test, named_data, false)) {
match = true;
break;
}
}
}
return match;
}
static bool hist_trigger_check_refs(struct event_trigger_data *data,
struct trace_event_file *file)
{
@ -3038,6 +3870,8 @@ static void hist_unreg_all(struct trace_event_file *file)
{
struct event_trigger_data *test, *n;
struct hist_trigger_data *hist_data;
struct synth_event *se;
const char *se_name;
if (hist_file_check_refs(file))
return;
@ -3047,6 +3881,14 @@ static void hist_unreg_all(struct trace_event_file *file)
hist_data = test->private_data;
list_del_rcu(&test->list);
trace_event_trigger_enable_disable(file, 0);
mutex_lock(&synth_event_mutex);
se_name = trace_event_name(file->event_call);
se = find_synth_event(se_name);
if (se)
se->ref--;
mutex_unlock(&synth_event_mutex);
update_cond_flag(file);
if (hist_data->enable_timestamps)
tracing_set_time_stamp_abs(file->tr, false);
@ -3065,6 +3907,8 @@ static int event_hist_trigger_func(struct event_command *cmd_ops,
struct hist_trigger_attrs *attrs;
struct event_trigger_ops *trigger_ops;
struct hist_trigger_data *hist_data;
struct synth_event *se;
const char *se_name;
bool remove = false;
char *trigger;
int ret = 0;
@ -3095,10 +3939,11 @@ static int event_hist_trigger_func(struct event_command *cmd_ops,
trigger_ops = cmd_ops->get_trigger_ops(cmd, trigger);
ret = -ENOMEM;
trigger_data = kzalloc(sizeof(*trigger_data), GFP_KERNEL);
if (!trigger_data)
if (!trigger_data) {
ret = -ENOMEM;
goto out_free;
}
trigger_data->count = -1;
trigger_data->ops = trigger_ops;
@ -3117,12 +3962,23 @@ static int event_hist_trigger_func(struct event_command *cmd_ops,
}
if (remove) {
if (!have_hist_trigger_match(trigger_data, file))
goto out_free;
if (hist_trigger_check_refs(trigger_data, file)) {
ret = -EBUSY;
goto out_free;
}
cmd_ops->unreg(glob+1, trigger_ops, trigger_data, file);
mutex_lock(&synth_event_mutex);
se_name = trace_event_name(file->event_call);
se = find_synth_event(se_name);
if (se)
se->ref--;
mutex_unlock(&synth_event_mutex);
ret = 0;
goto out_free;
}
@ -3158,6 +4014,13 @@ enable:
if (ret)
goto out_unreg;
mutex_lock(&synth_event_mutex);
se_name = trace_event_name(file->event_call);
se = find_synth_event(se_name);
if (se)
se->ref++;
mutex_unlock(&synth_event_mutex);
/* Just return zero, not the number of registered triggers */
ret = 0;
out:
@ -3330,3 +4193,31 @@ __init int register_trigger_hist_enable_disable_cmds(void)
return ret;
}
static __init int trace_events_hist_init(void)
{
struct dentry *entry = NULL;
struct dentry *d_tracer;
int err = 0;
d_tracer = tracing_init_dentry();
if (IS_ERR(d_tracer)) {
err = PTR_ERR(d_tracer);
goto err;
}
entry = tracefs_create_file("synthetic_events", 0644, d_tracer,
NULL, &synth_events_fops);
if (!entry) {
err = -ENODEV;
goto err;
}
return err;
err:
pr_warn("Could not create tracefs 'synthetic_events' entry\n");
return err;
}
fs_initcall(trace_events_hist_init);