Change in osmo-trx[master]: osmo-trx: Use signalfd to serialize signals in main thread ctx

[Pau Espin Pedrol]

Pau Espin Pedrol has submitted this change and it was merged. ( https://gerrit.osmocom.org/13468 )

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

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
---
M Transceiver52M/osmo-trx.cpp
1 file changed, 46 insertions(+), 5 deletions(-)

Approvals:
  Jenkins Builder: Verified
  Harald Welte: Looks good to me, approved



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 @@
 
 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 @@
 	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 @@
 
 	trx_stop();
 
+	osmo_fd_unregister(&signal_ofd);
+	osmo_fd_close(&signal_ofd);
 	return 0;
 }

-- 
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Gerrit-Project: osmo-trx
Gerrit-Branch: master
Gerrit-MessageType: merged
Gerrit-Change-Id: I9b9d9793be9af11dbe433e0ce09b7ac57a3bdfb5
Gerrit-Change-Number: 13468
Gerrit-PatchSet: 1
Gerrit-Owner: Pau Espin Pedrol <pespin at sysmocom.de>
Gerrit-Reviewer: Harald Welte <laforge at gnumonks.org>
Gerrit-Reviewer: Jenkins Builder (1000002)
Gerrit-Reviewer: Pau Espin Pedrol <pespin at sysmocom.de>
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