text: // SPDX-License-Identifier: GPL-2.0-only
  /*
   * Guest agent for virtio-trace
   *
   * Copyright (C) 2012 Hitachi, Ltd.
   * Created by Yoshihiro Yunomae <yoshihiro.yunomae.ez@hitachi.com>
   *            Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
   */
  
  #define _GNU_SOURCE
  #include <limits.h>
  #include <stdio.h>
  #include <stdlib.h>
  #include <unistd.h>
  #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 <size of pipe>]\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;
  }
  