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
22 static volatile sig_atomic_t global_signal_val;
23 bool global_sig_receive; /* default false */
24 bool global_run_operation; /* default false*/
25
26 /* Handle SIGTERM/SIGINT/SIGQUIT to exit */
signal_handler(int sig)27 static void signal_handler(int sig)
28 {
29 global_signal_val = sig;
30 }
31
rw_ctl_init(const char * ctl_path)32 int 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
44 error:
45 exit(EXIT_FAILURE);
46 }
47
wait_order(int ctl_fd)48 static 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
82 error:
83 exit(EXIT_FAILURE);
84 }
85
86 /*
87 * contol read/write threads by handling global_run_operation
88 */
rw_ctl_loop(int ctl_fd)89 void *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
133 error:
134 exit(EXIT_FAILURE);
135 }
136