1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Controller of read/write threads for virtio-trace
4 *
5 * Copyright (C) 2012 Hitachi, Ltd.
6 * Created by Yoshihiro Yunomae <yoshihiro.yunomae.ez@hitachi.com>
7 *            Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
8 */
9
10#define _GNU_SOURCE
11#include <fcntl.h>
12#include <poll.h>
13#include <signal.h>
14#include <stdio.h>
15#include <stdlib.h>
16#include <unistd.h>
17#include "trace-agent.h"
18
19#define HOST_MSG_SIZE		256
20#define EVENT_WAIT_MSEC		100
21
22static volatile sig_atomic_t global_signal_val;
23bool global_sig_receive;	/* default false */
24bool global_run_operation;	/* default false*/
25
26/* Handle SIGTERM/SIGINT/SIGQUIT to exit */
27static void signal_handler(int sig)
28{
29	global_signal_val = sig;
30}
31
32int rw_ctl_init(const char *ctl_path)
33{
34	int ctl_fd;
35
36	ctl_fd = open(ctl_path, O_RDONLY);
37	if (ctl_fd == -1) {
38		pr_err("Cannot open ctl_fd\n");
39		goto error;
40	}
41
42	return ctl_fd;
43
44error:
45	exit(EXIT_FAILURE);
46}
47
48static int wait_order(int ctl_fd)
49{
50	struct pollfd poll_fd;
51	int ret = 0;
52
53	while (!global_sig_receive) {
54		poll_fd.fd = ctl_fd;
55		poll_fd.events = POLLIN;
56
57		ret = poll(&poll_fd, 1, EVENT_WAIT_MSEC);
58
59		if (global_signal_val) {
60			global_sig_receive = true;
61			pr_info("Receive interrupt %d\n", global_signal_val);
62
63			/* Wakes rw-threads when they are sleeping */
64			if (!global_run_operation)
65				pthread_cond_broadcast(&cond_wakeup);
66
67			ret = -1;
68			break;
69		}
70
71		if (ret < 0) {
72			pr_err("Polling error\n");
73			goto error;
74		}
75
76		if (ret)
77			break;
78	}
79
80	return ret;
81
82error:
83	exit(EXIT_FAILURE);
84}
85
86/*
87 * contol read/write threads by handling global_run_operation
88 */
89void *rw_ctl_loop(int ctl_fd)
90{
91	ssize_t rlen;
92	char buf[HOST_MSG_SIZE];
93	int ret;
94
95	/* Setup signal handlers */
96	signal(SIGTERM, signal_handler);
97	signal(SIGINT, signal_handler);
98	signal(SIGQUIT, signal_handler);
99
100	while (!global_sig_receive) {
101
102		ret = wait_order(ctl_fd);
103		if (ret < 0)
104			break;
105
106		rlen = read(ctl_fd, buf, sizeof(buf));
107		if (rlen < 0) {
108			pr_err("read data error in ctl thread\n");
109			goto error;
110		}
111
112		if (rlen == 2 && buf[0] == '1') {
113			/*
114			 * If host writes '1' to a control path,
115			 * this controller wakes all read/write threads.
116			 */
117			global_run_operation = true;
118			pthread_cond_broadcast(&cond_wakeup);
119			pr_debug("Wake up all read/write threads\n");
120		} else if (rlen == 2 && buf[0] == '0') {
121			/*
122			 * If host writes '0' to a control path, read/write
123			 * threads will wait for notification from Host.
124			 */
125			global_run_operation = false;
126			pr_debug("Stop all read/write threads\n");
127		} else
128			pr_info("Invalid host notification: %s\n", buf);
129	}
130
131	return NULL;
132
133error:
134	exit(EXIT_FAILURE);
135}
136