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// SPDX-License-Identifier: LGPL-2.1
/*
* Copyright (C) 2021, VMware, Tzvetomir Stoyanov <tz.stoyanov@gmail.com>
*
*/
#include <stdlib.h>
#include <unistd.h>
#include <stdio.h>
#include <pthread.h>
#include "tracefs.h"
#include "tracefs-local.h"
/* File descriptors for Top level trace markers */
static int ftrace_marker_fd = -1;
static int ftrace_marker_raw_fd = -1;
static inline int *get_marker_fd(struct tracefs_instance *instance, bool raw)
{
if (raw)
return instance ? &instance->ftrace_marker_raw_fd : &ftrace_marker_raw_fd;
return instance ? &instance->ftrace_marker_fd : &ftrace_marker_fd;
}
static int marker_init(struct tracefs_instance *instance, bool raw)
{
const char *file = raw ? "trace_marker_raw" : "trace_marker";
pthread_mutex_t *lock = trace_get_lock(instance);
int *fd = get_marker_fd(instance, raw);
int ret;
if (*fd >= 0)
return 0;
/*
* The mutex is only to hold the integrity of the file descriptor
* to prevent opening it more than once, or closing the same
* file descriptor more than once. It does not protect against
* one thread closing the file descriptor and another thread
* writing to it. That is up to the application to prevent
* from happening.
*/
pthread_mutex_lock(lock);
/* The file could have been opened since we taken the lock */
if (*fd < 0)
*fd = tracefs_instance_file_open(instance, file, O_WRONLY | O_CLOEXEC);
ret = *fd < 0 ? -1 : 0;
pthread_mutex_unlock(lock);
return ret;
}
static void marker_close(struct tracefs_instance *instance, bool raw)
{
pthread_mutex_t *lock = trace_get_lock(instance);
int *fd = get_marker_fd(instance, raw);
pthread_mutex_lock(lock);
if (*fd >= 0) {
close(*fd);
*fd = -1;
}
pthread_mutex_unlock(lock);
}
static int marker_write(struct tracefs_instance *instance, bool raw, void *data, int len)
{
int *fd = get_marker_fd(instance, raw);
int ret;
/*
* The lock does not need to be taken for writes. As a write
* does not modify the file descriptor. It's up to the application
* to prevent it from being closed if another thread is doing a write.
*/
if (!data || len < 1)
return -1;
if (*fd < 0) {
ret = marker_init(instance, raw);
if (ret < 0)
return ret;
}
ret = write(*fd, data, len);
return ret == len ? 0 : -1;
}
/**
* tracefs_print_init - Open trace marker of selected instance for writing
* @instance: ftrace instance, can be NULL for top tracing instance.
*
* Returns 0 if the trace marker is opened successfully, or -1 in case of an error
*/
int tracefs_print_init(struct tracefs_instance *instance)
{
return marker_init(instance, false);
}
/**
* tracefs_vprintf - Write a formatted string in the trace marker
* @instance: ftrace instance, can be NULL for top tracing instance.
* @fmt: pritnf formatted string
* @ap: list of arguments for the formatted string
*
* If the trace marker of the desired instance is not open already,
* this API will open it for writing. It will stay open until
* tracefs_print_close() is called.
*
* Returns 0 if the string is written correctly, or -1 in case of an error
*/
int tracefs_vprintf(struct tracefs_instance *instance, const char *fmt, va_list ap)
{
char *str = NULL;
int ret;
ret = vasprintf(&str, fmt, ap);
if (ret < 0)
return ret;
ret = marker_write(instance, false, str, strlen(str));
free(str);
return ret;
}
/**
* tracefs_printf - Write a formatted string in the trace marker
* @instance: ftrace instance, can be NULL for top tracing instance.
* @fmt: pritnf formatted string with variable arguments ...
*
* If the trace marker of the desired instance is not open already,
* this API will open it for writing. It will stay open until
* tracefs_print_close() is called.
*
* Returns 0 if the string is written correctly, or -1 in case of an error
*/
int tracefs_printf(struct tracefs_instance *instance, const char *fmt, ...)
{
va_list ap;
int ret;
va_start(ap, fmt);
ret = tracefs_vprintf(instance, fmt, ap);
va_end(ap);
return ret;
}
/**
* tracefs_print_close - Close trace marker of selected instance
* @instance: ftrace instance, can be NULL for top tracing instance.
*
* Closes the trace marker, previously opened with any of the other tracefs_print APIs
*/
void tracefs_print_close(struct tracefs_instance *instance)
{
marker_close(instance, false);
}
/**
* tracefs_binary_init - Open raw trace marker of selected instance for writing
* @instance: ftrace instance, can be NULL for top tracing instance.
*
* Returns 0 if the raw trace marker is opened successfully, or -1 in case of an error
*/
int tracefs_binary_init(struct tracefs_instance *instance)
{
return marker_init(instance, true);
}
/**
* tracefs_binary_write - Write binary data in the raw trace marker
* @instance: ftrace instance, can be NULL for top tracing instance.
* @data: binary data, that is going to be written in the trace marker
* @len: length of the @data
*
* If the raw trace marker of the desired instance is not open already,
* this API will open it for writing. It will stay open until
* tracefs_binary_close() is called.
*
* Returns 0 if the data is written correctly, or -1 in case of an error
*/
int tracefs_binary_write(struct tracefs_instance *instance, void *data, int len)
{
return marker_write(instance, true, data, len);
}
/**
* tracefs_binary_close - Close raw trace marker of selected instance
* @instance: ftrace instance, can be NULL for top tracing instance.
*
* Closes the raw trace marker, previously opened with any of the other tracefs_binary APIs
*/
void tracefs_binary_close(struct tracefs_instance *instance)
{
marker_close(instance, true);
}
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