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/*
* trace event based perf counter profiling
*
* Copyright (C) 2009 Red Hat Inc, Peter Zijlstra <pzijlstr@redhat.com>
*
*/
#include <linux/module.h>
#include "trace.h"
/*
* We can't use a size but a type in alloc_percpu()
* So let's create a dummy type that matches the desired size
*/
typedef struct {char buf[FTRACE_MAX_PROFILE_SIZE];} profile_buf_t;
char *trace_profile_buf;
EXPORT_SYMBOL_GPL(trace_profile_buf);
char *trace_profile_buf_nmi;
EXPORT_SYMBOL_GPL(trace_profile_buf_nmi);
/* Count the events in use (per event id, not per instance) */
static int total_profile_count;
static int ftrace_profile_enable_event(struct ftrace_event_call *event)
{
char *buf;
int ret = -ENOMEM;
if (atomic_inc_return(&event->profile_count))
return 0;
if (!total_profile_count) {
buf = (char *)alloc_percpu(profile_buf_t);
if (!buf)
goto fail_buf;
rcu_assign_pointer(trace_profile_buf, buf);
buf = (char *)alloc_percpu(profile_buf_t);
if (!buf)
goto fail_buf_nmi;
rcu_assign_pointer(trace_profile_buf_nmi, buf);
}
ret = event->profile_enable();
if (!ret) {
total_profile_count++;
return 0;
}
fail_buf_nmi:
if (!total_profile_count) {
free_percpu(trace_profile_buf_nmi);
free_percpu(trace_profile_buf);
trace_profile_buf_nmi = NULL;
trace_profile_buf = NULL;
}
fail_buf:
atomic_dec(&event->profile_count);
return ret;
}
int ftrace_profile_enable(int event_id)
{
struct ftrace_event_call *event;
int ret = -EINVAL;
mutex_lock(&event_mutex);
list_for_each_entry(event, &ftrace_events, list) {
if (event->id == event_id && event->profile_enable &&
try_module_get(event->mod)) {
ret = ftrace_profile_enable_event(event);
break;
}
}
mutex_unlock(&event_mutex);
return ret;
}
static void ftrace_profile_disable_event(struct ftrace_event_call *event)
{
char *buf, *nmi_buf;
if (!atomic_add_negative(-1, &event->profile_count))
return;
event->profile_disable();
if (!--total_profile_count) {
buf = trace_profile_buf;
rcu_assign_pointer(trace_profile_buf, NULL);
nmi_buf = trace_profile_buf_nmi;
rcu_assign_pointer(trace_profile_buf_nmi, NULL);
/*
* Ensure every events in profiling have finished before
* releasing the buffers
*/
synchronize_sched();
free_percpu(buf);
free_percpu(nmi_buf);
}
}
void ftrace_profile_disable(int event_id)
{
struct ftrace_event_call *event;
mutex_lock(&event_mutex);
list_for_each_entry(event, &ftrace_events, list) {
if (event->id == event_id) {
ftrace_profile_disable_event(event);
module_put(event->mod);
break;
}
}
mutex_unlock(&event_mutex);
}
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