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
24 static volatile sig_atomic_t global_signal_val;
25 bool global_sig_receive; /* default false */
26 bool global_run_operation; /* default false*/
27
28 /* Handle SIGTERM/SIGINT/SIGQUIT to exit */
signal_handler(int sig)29 static void signal_handler(int sig)
30 {
31 global_signal_val = sig;
32 }
33
rw_ctl_init(const char * ctl_path)34 int 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
46 error:
47 exit(EXIT_FAILURE);
48 }
49
wait_order(int ctl_fd)50 static 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
84 error:
85 exit(EXIT_FAILURE);
86 }
87
88 /*
89 * contol read/write threads by handling global_run_operation
90 */
rw_ctl_loop(int ctl_fd)91 void *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
135 error:
136 exit(EXIT_FAILURE);
137 }
138