From 108fc82596e3b66b819df9d28c1ebbc9ab5de14c Mon Sep 17 00:00:00 2001 From: Yoshihiro YUNOMAE Date: Thu, 9 Aug 2012 21:31:30 +0900 Subject: tools: Add guest trace agent as a user tool This patch adds a user tool, "trace agent" for sending trace data of a guest to a Host in low overhead. This agent has the following functions: - splice a page of ring-buffer to read_pipe without memory copying - splice the page from write_pipe to virtio-console without memory copying - write trace data to stdout by using -o option - controlled by start/stop orders from a Host Changes in v2: - Cleanup (change fprintf() to pr_err() and an include guard) Signed-off-by: Yoshihiro YUNOMAE Acked-by: Amit Shah Signed-off-by: Rusty Russell --- tools/virtio/virtio-trace/Makefile | 14 ++ tools/virtio/virtio-trace/README | 118 ++++++++++++ tools/virtio/virtio-trace/trace-agent-ctl.c | 137 ++++++++++++++ tools/virtio/virtio-trace/trace-agent-rw.c | 192 ++++++++++++++++++++ tools/virtio/virtio-trace/trace-agent.c | 270 ++++++++++++++++++++++++++++ tools/virtio/virtio-trace/trace-agent.h | 75 ++++++++ 6 files changed, 806 insertions(+) create mode 100644 tools/virtio/virtio-trace/Makefile create mode 100644 tools/virtio/virtio-trace/README create mode 100644 tools/virtio/virtio-trace/trace-agent-ctl.c create mode 100644 tools/virtio/virtio-trace/trace-agent-rw.c create mode 100644 tools/virtio/virtio-trace/trace-agent.c create mode 100644 tools/virtio/virtio-trace/trace-agent.h (limited to 'tools/virtio') diff --git a/tools/virtio/virtio-trace/Makefile b/tools/virtio/virtio-trace/Makefile new file mode 100644 index 00000000000..ef3adfce594 --- /dev/null +++ b/tools/virtio/virtio-trace/Makefile @@ -0,0 +1,14 @@ +CC = gcc +CFLAGS = -O2 -Wall +LFLAG = -lpthread + +all: trace-agent + +.c.o: + $(CC) $(CFLAGS) $(LFLAG) -c $^ -o $@ + +trace-agent: trace-agent.o trace-agent-ctl.o trace-agent-rw.o + $(CC) $(CFLAGS) $(LFLAG) -o $@ $^ + +clean: + rm -f *.o trace-agent diff --git a/tools/virtio/virtio-trace/README b/tools/virtio/virtio-trace/README new file mode 100644 index 00000000000..b64845b823a --- /dev/null +++ b/tools/virtio/virtio-trace/README @@ -0,0 +1,118 @@ +Trace Agent for virtio-trace +============================ + +Trace agent is a user tool for sending trace data of a guest to a Host in low +overhead. Trace agent has the following functions: + - splice a page of ring-buffer to read_pipe without memory copying + - splice the page from write_pipe to virtio-console without memory copying + - write trace data to stdout by using -o option + - controlled by start/stop orders from a Host + +The trace agent operates as follows: + 1) Initialize all structures. + 2) Create a read/write thread per CPU. Each thread is bound to a CPU. + The read/write threads hold it. + 3) A controller thread does poll() for a start order of a host. + 4) After the controller of the trace agent receives a start order from a host, + the controller wake read/write threads. + 5) The read/write threads start to read trace data from ring-buffers and + write the data to virtio-serial. + 6) If the controller receives a stop order from a host, the read/write threads + stop to read trace data. + + +Files +===== + +README: this file +Makefile: Makefile of trace agent for virtio-trace +trace-agent.c: includes main function, sets up for operating trace agent +trace-agent.h: includes all structures and some macros +trace-agent-ctl.c: includes controller function for read/write threads +trace-agent-rw.c: includes read/write threads function + + +Setup +===== + +To use this trace agent for virtio-trace, we need to prepare some virtio-serial +I/Fs. + +1) Make FIFO in a host + virtio-trace uses virtio-serial pipe as trace data paths as to the number +of CPUs and a control path, so FIFO (named pipe) should be created as follows: + # mkdir /tmp/virtio-trace/ + # mkfifo /tmp/virtio-trace/trace-path-cpu{0,1,2,...,X}.{in,out} + # mkfifo /tmp/virtio-trace/agent-ctl-path.{in,out} + +For example, if a guest use three CPUs, the names are + trace-path-cpu{0,1,2}.{in.out} +and + agent-ctl-path.{in,out}. + +2) Set up of virtio-serial pipe in a host + Add qemu option to use virtio-serial pipe. + + ##virtio-serial device## + -device virtio-serial-pci,id=virtio-serial0\ + ##control path## + -chardev pipe,id=charchannel0,path=/tmp/virtio-trace/agent-ctl-path\ + -device virtserialport,bus=virtio-serial0.0,nr=1,chardev=charchannel0,\ + id=channel0,name=agent-ctl-path\ + ##data path## + -chardev pipe,id=charchannel1,path=/tmp/virtio-trace/trace-path-cpu0\ + -device virtserialport,bus=virtio-serial0.0,nr=2,chardev=charchannel0,\ + id=channel1,name=trace-path-cpu0\ + ... + +If you manage guests with libvirt, add the following tags to domain XML files. +Then, libvirt passes the same command option to qemu. + + + + +
+ + + + +
+ + ... +Here, chardev names are restricted to trace-path-cpuX and agent-ctl-path. For +example, if a guest use three CPUs, chardev names should be trace-path-cpu0, +trace-path-cpu1, trace-path-cpu2, and agent-ctl-path. + +3) Boot the guest + You can find some chardev in /dev/virtio-ports/ in the guest. + + +Run +=== + +0) Build trace agent in a guest + $ make + +1) Enable ftrace in the guest + + # echo 1 > /sys/kernel/debug/tracing/events/sched/enable + +2) Run trace agent in the guest + This agent must be operated as root. + # ./trace-agent +read/write threads in the agent wait for start order from host. If you add -o +option, trace data are output via stdout in the guest. + +3) Open FIFO in a host + # cat /tmp/virtio-trace/trace-path-cpu0.out +If a host does not open these, trace data get stuck in buffers of virtio. Then, +the guest will stop by specification of chardev in QEMU. This blocking mode may +be solved in the future. + +4) Start to read trace data by ordering from a host + A host injects read start order to the guest via virtio-serial. + # echo 1 > /tmp/virtio-trace/agent-ctl-path.in + +5) Stop to read trace data by ordering from a host + A host injects read stop order to the guest via virtio-serial. + # echo 0 > /tmp/virtio-trace/agent-ctl-path.in diff --git a/tools/virtio/virtio-trace/trace-agent-ctl.c b/tools/virtio/virtio-trace/trace-agent-ctl.c new file mode 100644 index 00000000000..a2d0403c4f9 --- /dev/null +++ b/tools/virtio/virtio-trace/trace-agent-ctl.c @@ -0,0 +1,137 @@ +/* + * Controller of read/write threads for virtio-trace + * + * Copyright (C) 2012 Hitachi, Ltd. + * Created by Yoshihiro Yunomae + * Masami Hiramatsu + * + * Licensed under GPL version 2 only. + * + */ + +#define _GNU_SOURCE +#include +#include +#include +#include +#include +#include +#include "trace-agent.h" + +#define HOST_MSG_SIZE 256 +#define EVENT_WAIT_MSEC 100 + +static volatile sig_atomic_t global_signal_val; +bool global_sig_receive; /* default false */ +bool global_run_operation; /* default false*/ + +/* Handle SIGTERM/SIGINT/SIGQUIT to exit */ +static void signal_handler(int sig) +{ + global_signal_val = sig; +} + +int rw_ctl_init(const char *ctl_path) +{ + int ctl_fd; + + ctl_fd = open(ctl_path, O_RDONLY); + if (ctl_fd == -1) { + pr_err("Cannot open ctl_fd\n"); + goto error; + } + + return ctl_fd; + +error: + exit(EXIT_FAILURE); +} + +static int wait_order(int ctl_fd) +{ + struct pollfd poll_fd; + int ret = 0; + + while (!global_sig_receive) { + poll_fd.fd = ctl_fd; + poll_fd.events = POLLIN; + + ret = poll(&poll_fd, 1, EVENT_WAIT_MSEC); + + if (global_signal_val) { + global_sig_receive = true; + pr_info("Receive interrupt %d\n", global_signal_val); + + /* Wakes rw-threads when they are sleeping */ + if (!global_run_operation) + pthread_cond_broadcast(&cond_wakeup); + + ret = -1; + break; + } + + if (ret < 0) { + pr_err("Polling error\n"); + goto error; + } + + if (ret) + break; + }; + + return ret; + +error: + exit(EXIT_FAILURE); +} + +/* + * contol read/write threads by handling global_run_operation + */ +void *rw_ctl_loop(int ctl_fd) +{ + ssize_t rlen; + char buf[HOST_MSG_SIZE]; + int ret; + + /* Setup signal handlers */ + signal(SIGTERM, signal_handler); + signal(SIGINT, signal_handler); + signal(SIGQUIT, signal_handler); + + while (!global_sig_receive) { + + ret = wait_order(ctl_fd); + if (ret < 0) + break; + + rlen = read(ctl_fd, buf, sizeof(buf)); + if (rlen < 0) { + pr_err("read data error in ctl thread\n"); + goto error; + } + + if (rlen == 2 && buf[0] == '1') { + /* + * If host writes '1' to a control path, + * this controller wakes all read/write threads. + */ + global_run_operation = true; + pthread_cond_broadcast(&cond_wakeup); + pr_debug("Wake up all read/write threads\n"); + } else if (rlen == 2 && buf[0] == '0') { + /* + * If host writes '0' to a control path, read/write + * threads will wait for notification from Host. + */ + global_run_operation = false; + pr_debug("Stop all read/write threads\n"); + } else + pr_info("Invalid host notification: %s\n", buf); + } + + return NULL; + +error: + exit(EXIT_FAILURE); +} diff --git a/tools/virtio/virtio-trace/trace-agent-rw.c b/tools/virtio/virtio-trace/trace-agent-rw.c new file mode 100644 index 00000000000..3aace5ea484 --- /dev/null +++ b/tools/virtio/virtio-trace/trace-agent-rw.c @@ -0,0 +1,192 @@ +/* + * Read/write thread of a guest agent for virtio-trace + * + * Copyright (C) 2012 Hitachi, Ltd. + * Created by Yoshihiro Yunomae + * Masami Hiramatsu + * + * Licensed under GPL version 2 only. + * + */ + +#define _GNU_SOURCE +#include +#include +#include +#include +#include +#include "trace-agent.h" + +#define READ_WAIT_USEC 100000 + +void *rw_thread_info_new(void) +{ + struct rw_thread_info *rw_ti; + + rw_ti = zalloc(sizeof(struct rw_thread_info)); + if (rw_ti == NULL) { + pr_err("rw_thread_info zalloc error\n"); + exit(EXIT_FAILURE); + } + + rw_ti->cpu_num = -1; + rw_ti->in_fd = -1; + rw_ti->out_fd = -1; + rw_ti->read_pipe = -1; + rw_ti->write_pipe = -1; + rw_ti->pipe_size = PIPE_INIT; + + return rw_ti; +} + +void *rw_thread_init(int cpu, const char *in_path, const char *out_path, + bool stdout_flag, unsigned long pipe_size, + struct rw_thread_info *rw_ti) +{ + int data_pipe[2]; + + rw_ti->cpu_num = cpu; + + /* set read(input) fd */ + rw_ti->in_fd = open(in_path, O_RDONLY); + if (rw_ti->in_fd == -1) { + pr_err("Could not open in_fd (CPU:%d)\n", cpu); + goto error; + } + + /* set write(output) fd */ + if (!stdout_flag) { + /* virtio-serial output mode */ + rw_ti->out_fd = open(out_path, O_WRONLY); + if (rw_ti->out_fd == -1) { + pr_err("Could not open out_fd (CPU:%d)\n", cpu); + goto error; + } + } else + /* stdout mode */ + rw_ti->out_fd = STDOUT_FILENO; + + if (pipe2(data_pipe, O_NONBLOCK) < 0) { + pr_err("Could not create pipe in rw-thread(%d)\n", cpu); + goto error; + } + + /* + * Size of pipe is 64kB in default based on fs/pipe.c. + * To read/write trace data speedy, pipe size is changed. + */ + if (fcntl(*data_pipe, F_SETPIPE_SZ, pipe_size) < 0) { + pr_err("Could not change pipe size in rw-thread(%d)\n", cpu); + goto error; + } + + rw_ti->read_pipe = data_pipe[1]; + rw_ti->write_pipe = data_pipe[0]; + rw_ti->pipe_size = pipe_size; + + return NULL; + +error: + exit(EXIT_FAILURE); +} + +/* Bind a thread to a cpu */ +static void bind_cpu(int cpu_num) +{ + cpu_set_t mask; + + CPU_ZERO(&mask); + CPU_SET(cpu_num, &mask); + + /* bind my thread to cpu_num by assigning zero to the first argument */ + if (sched_setaffinity(0, sizeof(mask), &mask) == -1) + pr_err("Could not set CPU#%d affinity\n", (int)cpu_num); +} + +static void *rw_thread_main(void *thread_info) +{ + ssize_t rlen, wlen; + ssize_t ret; + struct rw_thread_info *ts = (struct rw_thread_info *)thread_info; + + bind_cpu(ts->cpu_num); + + while (1) { + /* Wait for a read order of trace data by Host OS */ + if (!global_run_operation) { + pthread_mutex_lock(&mutex_notify); + pthread_cond_wait(&cond_wakeup, &mutex_notify); + pthread_mutex_unlock(&mutex_notify); + } + + if (global_sig_receive) + break; + + /* + * Each thread read trace_pipe_raw of each cpu bounding the + * thread, so contention of multi-threads does not occur. + */ + rlen = splice(ts->in_fd, NULL, ts->read_pipe, NULL, + ts->pipe_size, SPLICE_F_MOVE | SPLICE_F_MORE); + + if (rlen < 0) { + pr_err("Splice_read in rw-thread(%d)\n", ts->cpu_num); + goto error; + } else if (rlen == 0) { + /* + * If trace data do not exist or are unreadable not + * for exceeding the page size, splice_read returns + * NULL. Then, this waits for being filled the data in a + * ring-buffer. + */ + usleep(READ_WAIT_USEC); + pr_debug("Read retry(cpu:%d)\n", ts->cpu_num); + continue; + } + + wlen = 0; + + do { + ret = splice(ts->write_pipe, NULL, ts->out_fd, NULL, + rlen - wlen, + SPLICE_F_MOVE | SPLICE_F_MORE); + + if (ret < 0) { + pr_err("Splice_write in rw-thread(%d)\n", + ts->cpu_num); + goto error; + } else if (ret == 0) + /* + * When host reader is not in time for reading + * trace data, guest will be stopped. This is + * because char dev in QEMU is not supported + * non-blocking mode. Then, writer might be + * sleep in that case. + * This sleep will be removed by supporting + * non-blocking mode. + */ + sleep(1); + wlen += ret; + } while (wlen < rlen); + } + + return NULL; + +error: + exit(EXIT_FAILURE); +} + + +pthread_t rw_thread_run(struct rw_thread_info *rw_ti) +{ + int ret; + pthread_t rw_thread_per_cpu; + + ret = pthread_create(&rw_thread_per_cpu, NULL, rw_thread_main, rw_ti); + if (ret != 0) { + pr_err("Could not create a rw thread(%d)\n", rw_ti->cpu_num); + exit(EXIT_FAILURE); + } + + return rw_thread_per_cpu; +} diff --git a/tools/virtio/virtio-trace/trace-agent.c b/tools/virtio/virtio-trace/trace-agent.c new file mode 100644 index 00000000000..0a0a7dd4eff --- /dev/null +++ b/tools/virtio/virtio-trace/trace-agent.c @@ -0,0 +1,270 @@ +/* + * Guest agent for virtio-trace + * + * Copyright (C) 2012 Hitachi, Ltd. + * Created by Yoshihiro Yunomae + * Masami Hiramatsu + * + * Licensed under GPL version 2 only. + * + */ + +#define _GNU_SOURCE +#include +#include +#include +#include +#include "trace-agent.h" + +#define PAGE_SIZE (sysconf(_SC_PAGE_SIZE)) +#define PIPE_DEF_BUFS 16 +#define PIPE_MIN_SIZE (PAGE_SIZE*PIPE_DEF_BUFS) +#define PIPE_MAX_SIZE (1024*1024) +#define READ_PATH_FMT \ + "/sys/kernel/debug/tracing/per_cpu/cpu%d/trace_pipe_raw" +#define WRITE_PATH_FMT "/dev/virtio-ports/trace-path-cpu%d" +#define CTL_PATH "/dev/virtio-ports/agent-ctl-path" + +pthread_mutex_t mutex_notify = PTHREAD_MUTEX_INITIALIZER; +pthread_cond_t cond_wakeup = PTHREAD_COND_INITIALIZER; + +static int get_total_cpus(void) +{ + int nr_cpus = (int)sysconf(_SC_NPROCESSORS_CONF); + + if (nr_cpus <= 0) { + pr_err("Could not read cpus\n"); + goto error; + } else if (nr_cpus > MAX_CPUS) { + pr_err("Exceed max cpus(%d)\n", (int)MAX_CPUS); + goto error; + } + + return nr_cpus; + +error: + exit(EXIT_FAILURE); +} + +static void *agent_info_new(void) +{ + struct agent_info *s; + int i; + + s = zalloc(sizeof(struct agent_info)); + if (s == NULL) { + pr_err("agent_info zalloc error\n"); + exit(EXIT_FAILURE); + } + + s->pipe_size = PIPE_INIT; + s->use_stdout = false; + s->cpus = get_total_cpus(); + s->ctl_fd = -1; + + /* read/write threads init */ + for (i = 0; i < s->cpus; i++) + s->rw_ti[i] = rw_thread_info_new(); + + return s; +} + +static unsigned long parse_size(const char *arg) +{ + unsigned long value, round; + char *ptr; + + value = strtoul(arg, &ptr, 10); + switch (*ptr) { + case 'K': case 'k': + value <<= 10; + break; + case 'M': case 'm': + value <<= 20; + break; + default: + break; + } + + if (value > PIPE_MAX_SIZE) { + pr_err("Pipe size must be less than 1MB\n"); + goto error; + } else if (value < PIPE_MIN_SIZE) { + pr_err("Pipe size must be over 64KB\n"); + goto error; + } + + /* Align buffer size with page unit */ + round = value & (PAGE_SIZE - 1); + value = value - round; + + return value; +error: + return 0; +} + +static void usage(char const *prg) +{ + pr_err("usage: %s [-h] [-o] [-s ]\n", prg); +} + +static const char *make_path(int cpu_num, bool this_is_write_path) +{ + int ret; + char *buf; + + buf = zalloc(PATH_MAX); + if (buf == NULL) { + pr_err("Could not allocate buffer\n"); + goto error; + } + + if (this_is_write_path) + /* write(output) path */ + ret = snprintf(buf, PATH_MAX, WRITE_PATH_FMT, cpu_num); + else + /* read(input) path */ + ret = snprintf(buf, PATH_MAX, READ_PATH_FMT, cpu_num); + + if (ret <= 0) { + pr_err("Failed to generate %s path(CPU#%d):%d\n", + this_is_write_path ? "read" : "write", cpu_num, ret); + goto error; + } + + return buf; + +error: + free(buf); + return NULL; +} + +static const char *make_input_path(int cpu_num) +{ + return make_path(cpu_num, false); +} + +static const char *make_output_path(int cpu_num) +{ + return make_path(cpu_num, true); +} + +static void *agent_info_init(struct agent_info *s) +{ + int cpu; + const char *in_path = NULL; + const char *out_path = NULL; + + /* init read/write threads */ + for (cpu = 0; cpu < s->cpus; cpu++) { + /* set read(input) path per read/write thread */ + in_path = make_input_path(cpu); + if (in_path == NULL) + goto error; + + /* set write(output) path per read/write thread*/ + if (!s->use_stdout) { + out_path = make_output_path(cpu); + if (out_path == NULL) + goto error; + } else + /* stdout mode */ + pr_debug("stdout mode\n"); + + rw_thread_init(cpu, in_path, out_path, s->use_stdout, + s->pipe_size, s->rw_ti[cpu]); + } + + /* init controller of read/write threads */ + s->ctl_fd = rw_ctl_init((const char *)CTL_PATH); + + return NULL; + +error: + exit(EXIT_FAILURE); +} + +static void *parse_args(int argc, char *argv[], struct agent_info *s) +{ + int cmd; + unsigned long size; + + while ((cmd = getopt(argc, argv, "hos:")) != -1) { + switch (cmd) { + /* stdout mode */ + case 'o': + s->use_stdout = true; + break; + /* size of pipe */ + case 's': + size = parse_size(optarg); + if (size == 0) + goto error; + s->pipe_size = size; + break; + case 'h': + default: + usage(argv[0]); + goto error; + } + } + + agent_info_init(s); + + return NULL; + +error: + exit(EXIT_FAILURE); +} + +static void agent_main_loop(struct agent_info *s) +{ + int cpu; + pthread_t rw_thread_per_cpu[MAX_CPUS]; + + /* Start all read/write threads */ + for (cpu = 0; cpu < s->cpus; cpu++) + rw_thread_per_cpu[cpu] = rw_thread_run(s->rw_ti[cpu]); + + rw_ctl_loop(s->ctl_fd); + + /* Finish all read/write threads */ + for (cpu = 0; cpu < s->cpus; cpu++) { + int ret; + + ret = pthread_join(rw_thread_per_cpu[cpu], NULL); + if (ret != 0) { + pr_err("pthread_join() error:%d (cpu %d)\n", ret, cpu); + exit(EXIT_FAILURE); + } + } +} + +static void agent_info_free(struct agent_info *s) +{ + int i; + + close(s->ctl_fd); + for (i = 0; i < s->cpus; i++) { + close(s->rw_ti[i]->in_fd); + close(s->rw_ti[i]->out_fd); + close(s->rw_ti[i]->read_pipe); + close(s->rw_ti[i]->write_pipe); + free(s->rw_ti[i]); + } + free(s); +} + +int main(int argc, char *argv[]) +{ + struct agent_info *s = NULL; + + s = agent_info_new(); + parse_args(argc, argv, s); + + agent_main_loop(s); + + agent_info_free(s); + + return 0; +} diff --git a/tools/virtio/virtio-trace/trace-agent.h b/tools/virtio/virtio-trace/trace-agent.h new file mode 100644 index 00000000000..8de79bfeaa7 --- /dev/null +++ b/tools/virtio/virtio-trace/trace-agent.h @@ -0,0 +1,75 @@ +#ifndef __TRACE_AGENT_H__ +#define __TRACE_AGENT_H__ +#include +#include + +#define MAX_CPUS 256 +#define PIPE_INIT (1024*1024) + +/* + * agent_info - structure managing total information of guest agent + * @pipe_size: size of pipe (default 1MB) + * @use_stdout: set to true when o option is added (default false) + * @cpus: total number of CPUs + * @ctl_fd: fd of control path, /dev/virtio-ports/agent-ctl-path + * @rw_ti: structure managing information of read/write threads + */ +struct agent_info { + unsigned long pipe_size; + bool use_stdout; + int cpus; + int ctl_fd; + struct rw_thread_info *rw_ti[MAX_CPUS]; +}; + +/* + * rw_thread_info - structure managing a read/write thread a cpu + * @cpu_num: cpu number operating this read/write thread + * @in_fd: fd of reading trace data path in cpu_num + * @out_fd: fd of writing trace data path in cpu_num + * @read_pipe: fd of read pipe + * @write_pipe: fd of write pipe + * @pipe_size: size of pipe (default 1MB) + */ +struct rw_thread_info { + int cpu_num; + int in_fd; + int out_fd; + int read_pipe; + int write_pipe; + unsigned long pipe_size; +}; + +/* use for stopping rw threads */ +extern bool global_sig_receive; + +/* use for notification */ +extern bool global_run_operation; +extern pthread_mutex_t mutex_notify; +extern pthread_cond_t cond_wakeup; + +/* for controller of read/write threads */ +extern int rw_ctl_init(const char *ctl_path); +extern void *rw_ctl_loop(int ctl_fd); + +/* for trace read/write thread */ +extern void *rw_thread_info_new(void); +extern void *rw_thread_init(int cpu, const char *in_path, const char *out_path, + bool stdout_flag, unsigned long pipe_size, + struct rw_thread_info *rw_ti); +extern pthread_t rw_thread_run(struct rw_thread_info *rw_ti); + +static inline void *zalloc(size_t size) +{ + return calloc(1, size); +} + +#define pr_err(format, ...) fprintf(stderr, format, ## __VA_ARGS__) +#define pr_info(format, ...) fprintf(stdout, format, ## __VA_ARGS__) +#ifdef DEBUG +#define pr_debug(format, ...) fprintf(stderr, format, ## __VA_ARGS__) +#else +#define pr_debug(format, ...) do {} while (0) +#endif + +#endif /*__TRACE_AGENT_H__*/ -- cgit v1.2.3