trace-agent-ctl.c
2.61 KB
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/*
* Controller of read/write threads for virtio-trace
*
* Copyright (C) 2012 Hitachi, Ltd.
* Created by Yoshihiro Yunomae <yoshihiro.yunomae.ez@hitachi.com>
* Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
*
* Licensed under GPL version 2 only.
*
*/
#define _GNU_SOURCE
#include <fcntl.h>
#include <poll.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#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);
}