tools/virtio: add vring_test.
[linux-3.10.git] / tools / virtio / virtio-trace / trace-agent-ctl.c
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 */
29 static void signal_handler(int sig)
30 {
31         global_signal_val = sig;
32 }
33
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
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  */
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 }