osmo-trx: Use signalfd to serialize signals in main thread ctx

This should avoid prolematic scenarios where different signal handlers
are running on different thread in parallel. Furthermore, we make sure
those signals are always run by main loop thread.

Change-Id: I9b9d9793be9af11dbe433e0ce09b7ac57a3bdfb5

1 files changed, 46 insertions, 5 deletions

diff --git a/Transceiver52M/osmo-trx.cpp b/Transceiver52M/osmo-trx.cpp
index 0141810..88b9de0 100644
--- a/Transceiver52M/osmo-trx.cpp
+++ b/Transceiver52M/osmo-trx.cpp
@@ -34,6 +34,7 @@
 #include <string>
 #include <sstream>
 #include <iostream>
+#include <sys/signalfd.h>
 
 #include <GSMCommon.h>
 #include <Logger.h>
@@ -66,6 +67,7 @@ extern "C" {
 
 static char* config_file = (char*)DEFAULT_CONFIG_FILE;
 
+struct osmo_fd signal_ofd;
 volatile bool gshutdown = false;
 
 static void *tall_trx_ctx;
@@ -185,20 +187,57 @@ static void sig_handler(int signo)
 	case SIGUSR2:
 		talloc_report_full(tall_trx_ctx, stderr);
 		break;
+	case SIGHUP:
+		log_targets_reopen();
 	default:
 		break;
 	}
+
+}
+
+static int signalfd_callback(struct osmo_fd *ofd, unsigned int what)
+{
+	struct signalfd_siginfo fdsi;
+	ssize_t s;
+
+	s = read(ofd->fd, &fdsi, sizeof(struct signalfd_siginfo));
+	if (s < 0) {
+		LOG(FATAL) << "Failed to read from signalfd ("<< ofd->fd << "): " << errno;
+		gshutdown = true;
+		return 0;
+	}
+	sig_handler(fdsi.ssi_signo);
+	return 0;
 }
 
 static void setup_signal_handlers()
 {
-	/* Handle keyboard interrupt SIGINT */
-	signal(SIGINT, &sig_handler);
-	signal(SIGTERM, &sig_handler);
+	sigset_t set;
+	int sfd;
+
 	signal(SIGABRT, &sig_handler);
-	signal(SIGUSR1, &sig_handler);
-	signal(SIGUSR2, &sig_handler);
 	osmo_init_ignore_signals();
+
+	/* Other threads created by this thread (main) will inherit a copy of the
+	signal mask. */
+	sigemptyset(&set);
+	sigaddset(&set, SIGINT);
+	sigaddset(&set, SIGTERM);
+	sigaddset(&set, SIGUSR1);
+	sigaddset(&set, SIGUSR2);
+	sigaddset(&set, SIGHUP);
+	if (pthread_sigmask(SIG_BLOCK, &set, NULL)) {
+		fprintf(stderr, "pthread_sigmask() failed.\n");
+		exit(EXIT_FAILURE);
+	}
+
+	if ((sfd = signalfd(-1, &set, 0)) == -1) {
+		fprintf(stderr, "signalfd() failed (%d).\n", errno);
+		exit(EXIT_FAILURE);
+	}
+
+	osmo_fd_setup(&signal_ofd, sfd, OSMO_FD_READ, signalfd_callback, NULL, 0);
+	osmo_fd_register(&signal_ofd);
 }
 
 static void print_help()
@@ -594,5 +633,7 @@ int main(int argc, char *argv[])
 
 	trx_stop();
 
+	osmo_fd_unregister(&signal_ofd);
+	osmo_fd_close(&signal_ofd);
 	return 0;
 }