From: Guus Sliepen <guus@tinc-vpn.org>
Date: Fri, 14 Jan 2011 21:18:59 +0000 (+0100)
Subject: Introducing the Big Tinc Lock.
X-Git-Url: https://git.librecmc.org/?a=commitdiff_plain;h=6834b882015a9323672e9fce8811aa4283f196f0;p=oweals%2Ftinc.git

Introducing the Big Tinc Lock.

Now that tinc is multi-threaded, we need some form of synchronisation.  For
now, there is a single mutex which we lock whenever we do something with global
data structures. The main thread, from which timer events are handled, is
always locked unless it is sleeping for the next event, the other threads
receive incoming I/O unlocked, and lock to process the received data.

In the future more fine-grained locking should be used, probably in the form of
rwlocks, or lockless algorithms (maybe RCU).
---

diff --git a/src/linux/device.c b/src/linux/device.c
index c1ca0a2..40711cc 100644
--- a/src/linux/device.c
+++ b/src/linux/device.c
@@ -61,7 +61,9 @@ static void read_thread(void *arg) {
 
 	while(true) {
 		if(read_packet(&packet)) {
+			mutex_lock(&mutex);
 			route(myself, &packet);
+			mutex_unlock(&mutex);
 		} else {
 			if(errno == EAGAIN || errno == EINTR) {
 				errno = 0;
diff --git a/src/meta.c b/src/meta.c
index 43e1e19..b556e17 100644
--- a/src/meta.c
+++ b/src/meta.c
@@ -77,7 +77,9 @@ static bool process_meta(connection_t *c, char *reqbuf, int *len) {
 			if(c->tcplen > *len)
 				break;
 
+			mutex_lock(&mutex);
 			receive_tcppacket(c, reqbuf, c->tcplen);
+			mutex_unlock(&mutex);
 
 			memmove(reqbuf, reqbuf, *len - c->tcplen);
 			*len -= c->tcplen;
@@ -88,7 +90,11 @@ static bool process_meta(connection_t *c, char *reqbuf, int *len) {
 			else
 				*end++ = 0;
 
-			if(!receive_request(c, reqbuf))
+			mutex_lock(&mutex);
+			bool success = receive_request(c, reqbuf);
+			mutex_unlock(&mutex);
+
+			if(!success)
 				return false;
 
 			memmove(reqbuf, end, *len - (end - reqbuf));
diff --git a/src/net.c b/src/net.c
index 39b467d..2ffe03a 100644
--- a/src/net.c
+++ b/src/net.c
@@ -220,14 +220,18 @@ void handle_meta_connection_data(void *data) {
 
 		getsockopt(c->socket, SOL_SOCKET, SO_ERROR, &result, &len);
 
-		if(!result)
+		if(!result) {
+			mutex_lock(&mutex);
 			finish_connecting(c);
-		else {
+			mutex_unlock(&mutex);
+		} else {
 			ifdebug(CONNECTIONS) logger(LOG_DEBUG,
 					   "Error while connecting to %s (%s): %s",
 					   c->name, c->hostname, sockstrerror(result));
 			closesocket(c->socket);
+			mutex_lock(&mutex);
 			do_outgoing_connection(c);
+			mutex_unlock(&mutex);
 			return;
 		}
 	}
@@ -235,7 +239,7 @@ void handle_meta_connection_data(void *data) {
 	while(true) {
 		if (!receive_meta(c)) {
 			terminate_connection(c, c->status.active);
-			return;
+			break;
 		}
 	}
 }
@@ -368,7 +372,10 @@ int main_loop(void) {
 #endif
 
 	while(true) {
-		usleep(1000);
+		mutex_unlock(&mutex);
+		usleep(1000000);
+		mutex_lock(&mutex);
+
 		struct event *event;
 		while((event = get_expired_event())) {
 			event->handler(event->data);
diff --git a/src/net.h b/src/net.h
index d4523fc..2be797d 100644
--- a/src/net.h
+++ b/src/net.h
@@ -155,8 +155,8 @@ extern void load_all_subnets();
 
 #ifndef HAVE_MINGW
 #define closesocket(s) close(s)
-#else
-extern CRITICAL_SECTION mutex;
 #endif
 
+extern mutex_t mutex;
+
 #endif							/* __TINC_NET_H__ */
diff --git a/src/net_packet.c b/src/net_packet.c
index 2856c61..a985390 100644
--- a/src/net_packet.c
+++ b/src/net_packet.c
@@ -599,23 +599,26 @@ void handle_incoming_vpn_data(void *arg) {
 
 		sockaddrunmap(&from);		/* Some braindead IPv6 implementations do stupid things. */
 
+		mutex_lock(&mutex);
 		n = lookup_node_udp(&from);
 
 		if(!n) {
 			n = try_harder(&from, &pkt);
 			if(n)
 				update_node_udp(n, &from);
-			else ifdebug(PROTOCOL) {
+		}
+
+		if(n) {
+			receive_udppacket(n, &pkt);
+		} else {
+			ifdebug(PROTOCOL) {
 				hostname = sockaddr2hostname(&from);
 				logger(LOG_WARNING, "Received UDP packet from unknown source %s", hostname);
 				free(hostname);
-				continue;
 			}
-			else
-				continue;
 		}
 
-		receive_udppacket(n, &pkt);
+		mutex_unlock(&mutex);
 	}
 }
 
diff --git a/src/net_socket.c b/src/net_socket.c
index 28b6067..3c79cee 100644
--- a/src/net_socket.c
+++ b/src/net_socket.c
@@ -498,6 +498,7 @@ void handle_new_meta_connection(void *data) {
 
 		configure_tcp(c);
 
+		mutex_lock(&mutex);
 		connection_add(c);
 
 		c->allow_request = ID;
@@ -507,6 +508,7 @@ void handle_new_meta_connection(void *data) {
 			logger(LOG_ERR, "create_thread() failed: %s", strerror(errno));
 			abort();
 		}
+		mutex_unlock(&mutex);
 	}
 }
 
diff --git a/src/threads.h b/src/threads.h
index d55e59e..85aaced 100644
--- a/src/threads.h
+++ b/src/threads.h
@@ -38,6 +38,10 @@ static inline void thread_destroy(thread_t *tid) {
 static inline void mutex_create(mutex_t *mutex) {
 	pthread_mutex_init(mutex, NULL);
 }
+#if 1
+#define mutex_lock(m) logger(LOG_DEBUG, "mutex_lock() at " __FILE__ " line %d", __LINE__); pthread_mutex_lock(m)
+#define mutex_unlock(m) logger(LOG_DEBUG, "mutex_unlock() at " __FILE__ " line %d", __LINE__); pthread_mutex_unlock(m)
+#else
 static inline void mutex_lock(mutex_t *mutex) {
 	pthread_mutex_lock(mutex);
 }
@@ -45,5 +49,6 @@ static inline void mutex_unlock(mutex_t *mutex) {
 	pthread_mutex_unlock(mutex);
 }
 #endif
+#endif
 
 #endif
diff --git a/src/tincd.c b/src/tincd.c
index aab250a..9518676 100644
--- a/src/tincd.c
+++ b/src/tincd.c
@@ -110,6 +110,8 @@ static struct option const long_options[] = {
 	{NULL, 0, NULL, 0}
 };
 
+mutex_t mutex;
+
 #ifdef HAVE_MINGW
 static struct WSAData wsa_state;
 CRITICAL_SECTION mutex;
@@ -383,6 +385,8 @@ int main(int argc, char **argv) {
 
 	g_argv = argv;
 
+	mutex_create(&mutex);
+	mutex_lock(&mutex);
 	init_events();
 	init_configuration(&config_tree);