Revert a change to LinuxEthernetTap threading to eliminate out of order packet issues on some systems.

osdep/LinuxEthernetTap.cpp

@@ -185,148 +185,102 @@ LinuxEthernetTap::LinuxEthernetTap(
 
 	(void)::pipe(_shutdownSignalPipe);
 
-	_thread_init_l.lock();
-	for(unsigned int t=0;t<2;++t) {
-		_tapReaderThread[t] = std::thread([this, t]{
-			fd_set readfds,nullfds;
-			int n,nfds,r;
-			void *buf = nullptr;
-			std::vector<void *> buffers;
-
-			if (t == 0) {
-				struct ifreq ifr;
-				memset(&ifr,0,sizeof(ifr));
-				strcpy(ifr.ifr_name,_dev.c_str());
-
-				const int sock = socket(AF_INET,SOCK_DGRAM,0);
-				if (sock <= 0)
-					return;
-
-				if (ioctl(sock,SIOCGIFFLAGS,(void *)&ifr) < 0) {
-					::close(sock);
-					printf("WARNING: ioctl() failed setting up Linux tap device (bring interface up)\n");
-					return;
-				}
-
-				ifr.ifr_ifru.ifru_hwaddr.sa_family = ARPHRD_ETHER;
-				_mac.copyTo(ifr.ifr_ifru.ifru_hwaddr.sa_data,6);
-				if (ioctl(sock,SIOCSIFHWADDR,(void *)&ifr) < 0) {
-					::close(sock);
-					printf("WARNING: ioctl() failed setting up Linux tap device (set MAC)\n");
-					return;
-				}
-
-				ifr.ifr_flags |= IFF_UP;
-				if (ioctl(sock,SIOCSIFFLAGS,(void *)&ifr) < 0) {
-					::close(sock);
-					printf("WARNING: ioctl() failed setting up Linux tap device (bring interface up)\n");
-					return;
-				}
-
-				// Some kernel versions seem to require you to yield while the device comes up
-				// before they will accept MTU and MAC. For others it doesn't matter, but is
-				// harmless. This was moved to the worker thread though so as not to block the
-				// main ZeroTier loop.
-				usleep(500000);
-
-				ifr.ifr_ifru.ifru_mtu = (int)_mtu;
-				if (ioctl(sock,SIOCSIFMTU,(void *)&ifr) < 0) {
-					::close(sock);
-					printf("WARNING: ioctl() failed setting up Linux tap device (set MTU)\n");
-					return;
-				}
+	_tapReaderThread = std::thread([this]{
+		uint8_t b[ZT_TAP_BUF_SIZE];
+		fd_set readfds,nullfds;
+		int n,nfds,r;
+		std::vector<void *> buffers;
+		struct ifreq ifr;
+
+		memset(&ifr,0,sizeof(ifr));
+		strcpy(ifr.ifr_name,_dev.c_str());
+
+		const int sock = socket(AF_INET,SOCK_DGRAM,0);
+		if (sock <= 0)
+			return;
+
+		if (ioctl(sock,SIOCGIFFLAGS,(void *)&ifr) < 0) {
+			::close(sock);
+			printf("WARNING: ioctl() failed setting up Linux tap device (bring interface up)\n");
+			return;
+		}
 
-				fcntl(_fd,F_SETFL,O_NONBLOCK);
+		ifr.ifr_ifru.ifru_hwaddr.sa_family = ARPHRD_ETHER;
+		_mac.copyTo(ifr.ifr_ifru.ifru_hwaddr.sa_data,6);
+		if (ioctl(sock,SIOCSIFHWADDR,(void *)&ifr) < 0) {
+			::close(sock);
+			printf("WARNING: ioctl() failed setting up Linux tap device (set MAC)\n");
+			return;
+		}
 
-				::close(sock);
+		ifr.ifr_flags |= IFF_UP;
+		if (ioctl(sock,SIOCSIFFLAGS,(void *)&ifr) < 0) {
+			::close(sock);
+			printf("WARNING: ioctl() failed setting up Linux tap device (bring interface up)\n");
+			return;
+		}
 
-				_thread_init_l.unlock();
-			} else {
-				_thread_init_l.lock();
-				_thread_init_l.unlock();
-			}
+		// Some kernel versions seem to require you to yield while the device comes up
+		// before they will accept MTU and MAC. For others it doesn't matter, but is
+		// harmless. This was moved to the worker thread though so as not to block the
+		// main ZeroTier loop.
+		usleep(500000);
+
+		ifr.ifr_ifru.ifru_mtu = (int)_mtu;
+		if (ioctl(sock,SIOCSIFMTU,(void *)&ifr) < 0) {
+			::close(sock);
+			printf("WARNING: ioctl() failed setting up Linux tap device (set MTU)\n");
+			return;
+		}
 
-			if (!_run)
-				return;
-
-			FD_ZERO(&readfds);
-			FD_ZERO(&nullfds);
-			nfds = (int)std::max(_shutdownSignalPipe[0],_fd) + 1;
-
-			r = 0;
-			for(;;) {
-				FD_SET(_shutdownSignalPipe[0],&readfds);
-				FD_SET(_fd,&readfds);
-				select(nfds,&readfds,&nullfds,&nullfds,(struct timeval *)0);
-
-				if (FD_ISSET(_shutdownSignalPipe[0],&readfds)) // writes to shutdown pipe terminate thread
-					break;
-
-				if (FD_ISSET(_fd,&readfds)) {
-					for(;;) { // read until there are no more packets, then return to outer select() loop
-						if (!buf) {
-							// To reduce use of the mutex, we keep a local buffer vector and
-							// swap (which is a pointer swap) with the global one when it's
-							// empty. This retrieves a batch of buffers to use.
-							if (buffers.empty()) {
-								std::lock_guard<std::mutex> l(_buffers_l);
-								buffers.swap(_buffers);
-							}
-							if (buffers.empty()) {
-								buf = malloc(ZT_TAP_BUF_SIZE);
-								if (!buf)
-									break;
-							} else {
-								buf = buffers.back();
-								buffers.pop_back();
+		fcntl(_fd,F_SETFL,O_NONBLOCK);
+
+		::close(sock);
+
+		if (!_run)
+			return;
+
+		FD_ZERO(&readfds);
+		FD_ZERO(&nullfds);
+		nfds = (int)std::max(_shutdownSignalPipe[0],_fd) + 1;
+
+		r = 0;
+		for(;;) {
+			FD_SET(_shutdownSignalPipe[0],&readfds);
+			FD_SET(_fd,&readfds);
+			select(nfds,&readfds,&nullfds,&nullfds,(struct timeval *)0);
+
+			if (FD_ISSET(_shutdownSignalPipe[0],&readfds))
+				break;
+
+			if (FD_ISSET(_fd,&readfds)) {
+				for(;;) { // read until there are no more packets, then return to outer select() loop
+					n = (int)::read(_fd,b + r,ZT_TAP_BUF_SIZE - r);
+					if (n > 0) {
+						// Some tap drivers like to send the ethernet frame and the
+						// payload in two chunks, so handle that by accumulating
+						// data until we have at least a frame.
+						r += n;
+						if (r > 14) {
+							if (r > ((int)_mtu + 14)) // sanity check for weird TAP behavior on some platforms
+								r = _mtu + 14;
+
+							if (_enabled) {
+								//_tapq.post(std::pair<void *,int>(buf,r));
+								//buf = nullptr;
+								MAC to(b, 6),from(b + 6, 6);
+								unsigned int etherType = Utils::ntoh(((const uint16_t *)b)[6]);
+								_handler(_arg, nullptr, _nwid, from, to, etherType, 0, (const void *)(b + 14),(unsigned int)(r - 14));
 							}
-						}
-
-						n = (int)::read(_fd,reinterpret_cast<uint8_t *>(buf) + r,ZT_TAP_BUF_SIZE - r);
-
-						if (n > 0) {
-							// Some tap drivers like to send the ethernet frame and the
-							// payload in two chunks, so handle that by accumulating
-							// data until we have at least a frame.
-							r += n;
-							if (r > 14) {
-								if (r > ((int)_mtu + 14)) // sanity check for weird TAP behavior on some platforms
-									r = _mtu + 14;
-
-								if (_enabled) {
-									_tapq.post(std::pair<void *,int>(buf,r));
-									buf = nullptr;
-								}
 
-								r = 0;
-							}
-						} else {
 							r = 0;
-							break;
 						}
+					} else {
+						r = 0;
+						break;
 					}
 				}
 			}
-		});
-	}
-
-	_tapProcessorThread = std::thread([this] {
-		MAC to,from;
-		std::pair<void *,int> qi;
-		while (_tapq.get(qi)) {
-			uint8_t *const b = reinterpret_cast<uint8_t *>(qi.first);
-			if (b) {
-				to.setTo(b, 6);
-				from.setTo(b + 6, 6);
-				unsigned int etherType = Utils::ntoh(((const uint16_t *)b)[6]);
-				_handler(_arg, nullptr, _nwid, from, to, etherType, 0, (const void *)(b + 14),(unsigned int)(qi.second - 14));
-				{
-					std::lock_guard<std::mutex> l(_buffers_l);
-					if (_buffers.size() < 128)
-						_buffers.push_back(qi.first);
-					else free(qi.first);
-				}
-			} else break;
 		}
 	});
 }
@@ -334,25 +288,11 @@ LinuxEthernetTap::LinuxEthernetTap(
 LinuxEthernetTap::~LinuxEthernetTap()
 {
 	_run = false;
-
-	(void)::write(_shutdownSignalPipe[1],"\0",1); // causes reader thread(s) to exit
-	_tapq.post(std::pair<void *,int>(nullptr,0)); // causes processor thread to exit
-
-	_tapReaderThread[0].join();
-	_tapReaderThread[1].join();
-	_tapProcessorThread.join();
-
+	(void)::write(_shutdownSignalPipe[1],"\0",1);
+	_tapReaderThread.join();
 	::close(_fd);
 	::close(_shutdownSignalPipe[0]);
 	::close(_shutdownSignalPipe[1]);
-
-	for(std::vector<void *>::iterator i(_buffers.begin());i!=_buffers.end();++i)
-		free(*i);
-	std::vector< std::pair<void *,int> > dv(_tapq.drain());
-	for(std::vector< std::pair<void *,int> >::iterator i(dv.begin());i!=dv.end();++i) {
-		if (i->first)
-			free(i->first);
-	}
 }
 
 void LinuxEthernetTap::setEnabled(bool en)

osdep/LinuxEthernetTap.hpp

@@ -26,7 +26,6 @@
 #include <mutex>
 #include "../node/MulticastGroup.hpp"
 #include "EthernetTap.hpp"
-#include "BlockingQueue.hpp"
 
 namespace ZeroTier {
 
@@ -71,12 +70,7 @@ private:
 	int _shutdownSignalPipe[2];
 	std::atomic_bool _enabled;
 	std::atomic_bool _run;
-	std::thread _tapReaderThread[2];
-	std::thread _tapProcessorThread;
-	std::mutex _buffers_l;
-	std::mutex _thread_init_l;
-	std::vector<void *> _buffers;
-	BlockingQueue< std::pair<void *,int> > _tapq;
+	std::thread _tapReaderThread;
 };
 
 } // namespace ZeroTier