1*4882a593Smuzhiyun // SPDX-License-Identifier: GPL-2.0-only
2*4882a593Smuzhiyun /*
3*4882a593Smuzhiyun * Controller of read/write threads for virtio-trace
4*4882a593Smuzhiyun *
5*4882a593Smuzhiyun * Copyright (C) 2012 Hitachi, Ltd.
6*4882a593Smuzhiyun * Created by Yoshihiro Yunomae <yoshihiro.yunomae.ez@hitachi.com>
7*4882a593Smuzhiyun * Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
8*4882a593Smuzhiyun */
9*4882a593Smuzhiyun
10*4882a593Smuzhiyun #define _GNU_SOURCE
11*4882a593Smuzhiyun #include <fcntl.h>
12*4882a593Smuzhiyun #include <poll.h>
13*4882a593Smuzhiyun #include <signal.h>
14*4882a593Smuzhiyun #include <stdio.h>
15*4882a593Smuzhiyun #include <stdlib.h>
16*4882a593Smuzhiyun #include <unistd.h>
17*4882a593Smuzhiyun #include "trace-agent.h"
18*4882a593Smuzhiyun
19*4882a593Smuzhiyun #define HOST_MSG_SIZE 256
20*4882a593Smuzhiyun #define EVENT_WAIT_MSEC 100
21*4882a593Smuzhiyun
22*4882a593Smuzhiyun static volatile sig_atomic_t global_signal_val;
23*4882a593Smuzhiyun bool global_sig_receive; /* default false */
24*4882a593Smuzhiyun bool global_run_operation; /* default false*/
25*4882a593Smuzhiyun
26*4882a593Smuzhiyun /* Handle SIGTERM/SIGINT/SIGQUIT to exit */
signal_handler(int sig)27*4882a593Smuzhiyun static void signal_handler(int sig)
28*4882a593Smuzhiyun {
29*4882a593Smuzhiyun global_signal_val = sig;
30*4882a593Smuzhiyun }
31*4882a593Smuzhiyun
rw_ctl_init(const char * ctl_path)32*4882a593Smuzhiyun int rw_ctl_init(const char *ctl_path)
33*4882a593Smuzhiyun {
34*4882a593Smuzhiyun int ctl_fd;
35*4882a593Smuzhiyun
36*4882a593Smuzhiyun ctl_fd = open(ctl_path, O_RDONLY);
37*4882a593Smuzhiyun if (ctl_fd == -1) {
38*4882a593Smuzhiyun pr_err("Cannot open ctl_fd\n");
39*4882a593Smuzhiyun goto error;
40*4882a593Smuzhiyun }
41*4882a593Smuzhiyun
42*4882a593Smuzhiyun return ctl_fd;
43*4882a593Smuzhiyun
44*4882a593Smuzhiyun error:
45*4882a593Smuzhiyun exit(EXIT_FAILURE);
46*4882a593Smuzhiyun }
47*4882a593Smuzhiyun
wait_order(int ctl_fd)48*4882a593Smuzhiyun static int wait_order(int ctl_fd)
49*4882a593Smuzhiyun {
50*4882a593Smuzhiyun struct pollfd poll_fd;
51*4882a593Smuzhiyun int ret = 0;
52*4882a593Smuzhiyun
53*4882a593Smuzhiyun while (!global_sig_receive) {
54*4882a593Smuzhiyun poll_fd.fd = ctl_fd;
55*4882a593Smuzhiyun poll_fd.events = POLLIN;
56*4882a593Smuzhiyun
57*4882a593Smuzhiyun ret = poll(&poll_fd, 1, EVENT_WAIT_MSEC);
58*4882a593Smuzhiyun
59*4882a593Smuzhiyun if (global_signal_val) {
60*4882a593Smuzhiyun global_sig_receive = true;
61*4882a593Smuzhiyun pr_info("Receive interrupt %d\n", global_signal_val);
62*4882a593Smuzhiyun
63*4882a593Smuzhiyun /* Wakes rw-threads when they are sleeping */
64*4882a593Smuzhiyun if (!global_run_operation)
65*4882a593Smuzhiyun pthread_cond_broadcast(&cond_wakeup);
66*4882a593Smuzhiyun
67*4882a593Smuzhiyun ret = -1;
68*4882a593Smuzhiyun break;
69*4882a593Smuzhiyun }
70*4882a593Smuzhiyun
71*4882a593Smuzhiyun if (ret < 0) {
72*4882a593Smuzhiyun pr_err("Polling error\n");
73*4882a593Smuzhiyun goto error;
74*4882a593Smuzhiyun }
75*4882a593Smuzhiyun
76*4882a593Smuzhiyun if (ret)
77*4882a593Smuzhiyun break;
78*4882a593Smuzhiyun };
79*4882a593Smuzhiyun
80*4882a593Smuzhiyun return ret;
81*4882a593Smuzhiyun
82*4882a593Smuzhiyun error:
83*4882a593Smuzhiyun exit(EXIT_FAILURE);
84*4882a593Smuzhiyun }
85*4882a593Smuzhiyun
86*4882a593Smuzhiyun /*
87*4882a593Smuzhiyun * contol read/write threads by handling global_run_operation
88*4882a593Smuzhiyun */
rw_ctl_loop(int ctl_fd)89*4882a593Smuzhiyun void *rw_ctl_loop(int ctl_fd)
90*4882a593Smuzhiyun {
91*4882a593Smuzhiyun ssize_t rlen;
92*4882a593Smuzhiyun char buf[HOST_MSG_SIZE];
93*4882a593Smuzhiyun int ret;
94*4882a593Smuzhiyun
95*4882a593Smuzhiyun /* Setup signal handlers */
96*4882a593Smuzhiyun signal(SIGTERM, signal_handler);
97*4882a593Smuzhiyun signal(SIGINT, signal_handler);
98*4882a593Smuzhiyun signal(SIGQUIT, signal_handler);
99*4882a593Smuzhiyun
100*4882a593Smuzhiyun while (!global_sig_receive) {
101*4882a593Smuzhiyun
102*4882a593Smuzhiyun ret = wait_order(ctl_fd);
103*4882a593Smuzhiyun if (ret < 0)
104*4882a593Smuzhiyun break;
105*4882a593Smuzhiyun
106*4882a593Smuzhiyun rlen = read(ctl_fd, buf, sizeof(buf));
107*4882a593Smuzhiyun if (rlen < 0) {
108*4882a593Smuzhiyun pr_err("read data error in ctl thread\n");
109*4882a593Smuzhiyun goto error;
110*4882a593Smuzhiyun }
111*4882a593Smuzhiyun
112*4882a593Smuzhiyun if (rlen == 2 && buf[0] == '1') {
113*4882a593Smuzhiyun /*
114*4882a593Smuzhiyun * If host writes '1' to a control path,
115*4882a593Smuzhiyun * this controller wakes all read/write threads.
116*4882a593Smuzhiyun */
117*4882a593Smuzhiyun global_run_operation = true;
118*4882a593Smuzhiyun pthread_cond_broadcast(&cond_wakeup);
119*4882a593Smuzhiyun pr_debug("Wake up all read/write threads\n");
120*4882a593Smuzhiyun } else if (rlen == 2 && buf[0] == '0') {
121*4882a593Smuzhiyun /*
122*4882a593Smuzhiyun * If host writes '0' to a control path, read/write
123*4882a593Smuzhiyun * threads will wait for notification from Host.
124*4882a593Smuzhiyun */
125*4882a593Smuzhiyun global_run_operation = false;
126*4882a593Smuzhiyun pr_debug("Stop all read/write threads\n");
127*4882a593Smuzhiyun } else
128*4882a593Smuzhiyun pr_info("Invalid host notification: %s\n", buf);
129*4882a593Smuzhiyun }
130*4882a593Smuzhiyun
131*4882a593Smuzhiyun return NULL;
132*4882a593Smuzhiyun
133*4882a593Smuzhiyun error:
134*4882a593Smuzhiyun exit(EXIT_FAILURE);
135*4882a593Smuzhiyun }
136