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1// SPDX-License-Identifier: GPL-2.0-only2/*3 * Controller of read/write threads for virtio-trace4 *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_SOURCE11#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 25620#define EVENT_WAIT_MSEC 10021 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_operation88 */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/write123 * threads will wait for notification from Host.124 */125 global_run_operation = false;126 pr_debug("Stop all read/write threads\n");127 } else128 pr_info("Invalid host notification: %s\n", buf);129 }130 131 return NULL;132 133error:134 exit(EXIT_FAILURE);135}136