1/*
2 * Controller of read/write threads for virtio-trace
3 *
4 * Copyright (C) 2012 Hitachi, Ltd.
5 * Created by Yoshihiro Yunomae <yoshihiro.yunomae.ez@hitachi.com>
6 *            Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
7 *
8 * Licensed under GPL version 2 only.
9 *
10 */
11
12#define _GNU_SOURCE
13#include <fcntl.h>
14#include <poll.h>
15#include <signal.h>
16#include <stdio.h>
17#include <stdlib.h>
18#include <unistd.h>
19#include "trace-agent.h"
20
21#define HOST_MSG_SIZE		256
22#define EVENT_WAIT_MSEC		100
23
24static volatile sig_atomic_t global_signal_val;
25bool global_sig_receive;	/* default false */
26bool global_run_operation;	/* default false*/
27
28/* Handle SIGTERM/SIGINT/SIGQUIT to exit */
29static void signal_handler(int sig)
30{
31	global_signal_val = sig;
32}
33
34int rw_ctl_init(const char *ctl_path)
35{
36	int ctl_fd;
37
38	ctl_fd = open(ctl_path, O_RDONLY);
39	if (ctl_fd == -1) {
40		pr_err("Cannot open ctl_fd\n");
41		goto error;
42	}
43
44	return ctl_fd;
45
46error:
47	exit(EXIT_FAILURE);
48}
49
50static int wait_order(int ctl_fd)
51{
52	struct pollfd poll_fd;
53	int ret = 0;
54
55	while (!global_sig_receive) {
56		poll_fd.fd = ctl_fd;
57		poll_fd.events = POLLIN;
58
59		ret = poll(&poll_fd, 1, EVENT_WAIT_MSEC);
60
61		if (global_signal_val) {
62			global_sig_receive = true;
63			pr_info("Receive interrupt %d\n", global_signal_val);
64
65			/* Wakes rw-threads when they are sleeping */
66			if (!global_run_operation)
67				pthread_cond_broadcast(&cond_wakeup);
68
69			ret = -1;
70			break;
71		}
72
73		if (ret < 0) {
74			pr_err("Polling error\n");
75			goto error;
76		}
77
78		if (ret)
79			break;
80	};
81
82	return ret;
83
84error:
85	exit(EXIT_FAILURE);
86}
87
88/*
89 * contol read/write threads by handling global_run_operation
90 */
91void *rw_ctl_loop(int ctl_fd)
92{
93	ssize_t rlen;
94	char buf[HOST_MSG_SIZE];
95	int ret;
96
97	/* Setup signal handlers */
98	signal(SIGTERM, signal_handler);
99	signal(SIGINT, signal_handler);
100	signal(SIGQUIT, signal_handler);
101
102	while (!global_sig_receive) {
103
104		ret = wait_order(ctl_fd);
105		if (ret < 0)
106			break;
107
108		rlen = read(ctl_fd, buf, sizeof(buf));
109		if (rlen < 0) {
110			pr_err("read data error in ctl thread\n");
111			goto error;
112		}
113
114		if (rlen == 2 && buf[0] == '1') {
115			/*
116			 * If host writes '1' to a control path,
117			 * this controller wakes all read/write threads.
118			 */
119			global_run_operation = true;
120			pthread_cond_broadcast(&cond_wakeup);
121			pr_debug("Wake up all read/write threads\n");
122		} else if (rlen == 2 && buf[0] == '0') {
123			/*
124			 * If host writes '0' to a control path, read/write
125			 * threads will wait for notification from Host.
126			 */
127			global_run_operation = false;
128			pr_debug("Stop all read/write threads\n");
129		} else
130			pr_info("Invalid host notification: %s\n", buf);
131	}
132
133	return NULL;
134
135error:
136	exit(EXIT_FAILURE);
137}
138