net: Don't copy every packet that waits for an ARP

Use the NetArpTxPacket for the ARP packet, not to hold what used to
be in NetTxPacket.
This saves a copy and makes the code easier to understand.

Signed-off-by: Joe Hershberger <joe.hershberger@ni.com>
Acked-by: Simon Glass <sjg@chromium.org>

include/net.h

@@ -483,14 +483,14 @@ static inline void net_set_state(enum net_loop_state state)
 	net_state = state;
 }
 
-/* Transmit "NetTxPacket" */
+/* Transmit a packet */
 static inline void NetSendPacket(uchar *pkt, int len)
 {
 	(void) eth_send(pkt, len);
 }
 
 /*
- * Transmit UDP packet, performing ARP request if needed
+ * Transmit "NetTxPacket" as UDP packet, performing ARP request if needed
  *  (ether will be populated)
  *
  * @param ether Raw packet buffer
@@ -499,7 +499,7 @@ static inline void NetSendPacket(uchar *pkt, int len)
  * @param sport Source UDP port
  * @param payload_len Length of data after the UDP header
  */
-extern int	NetSendUDPPacket(uchar *ether, IPaddr_t dest, int dport,
+extern int NetSendUDPPacket(uchar *ether, IPaddr_t dest, int dport,
 			int sport, int payload_len);
 
 /* Processes a received packet */

net/arp.c

@@ -30,22 +30,22 @@ IPaddr_t	NetArpWaitPacketIP;
 IPaddr_t	NetArpWaitReplyIP;
 /* MAC address of waiting packet's destination */
 uchar	       *NetArpWaitPacketMAC;
-/* THE transmit packet */
-uchar	       *NetArpWaitTxPacket;
 int		NetArpWaitTxPacketSize;
-uchar		NetArpWaitPacketBuf[PKTSIZE_ALIGN + PKTALIGN];
 ulong		NetArpWaitTimerStart;
 int		NetArpWaitTry;
 
+uchar	       *NetArpTxPacket;	/* THE ARP transmit packet */
+uchar		NetArpPacketBuf[PKTSIZE_ALIGN + PKTALIGN];
+
 void ArpInit(void)
 {
 	/* XXX problem with bss workaround */
 	NetArpWaitPacketMAC = NULL;
 	NetArpWaitPacketIP = 0;
 	NetArpWaitReplyIP = 0;
-	NetArpWaitTxPacket = &NetArpWaitPacketBuf[0] + (PKTALIGN - 1);
-	NetArpWaitTxPacket -= (ulong)NetArpWaitTxPacket % PKTALIGN;
 	NetArpWaitTxPacketSize = 0;
+	NetArpTxPacket = &NetArpPacketBuf[0] + (PKTALIGN - 1);
+	NetArpTxPacket -= (ulong)NetArpTxPacket % PKTALIGN;
 }
 
 void ArpRequest(void)
@@ -56,7 +56,7 @@ void ArpRequest(void)
 
 	debug("ARP broadcast %d\n", NetArpWaitTry);
 
-	pkt = NetTxPacket;
+	pkt = NetArpTxPacket;
 
 	eth_hdr_size = NetSetEther(pkt, NetBcastAddr, PROT_ARP);
 	pkt += eth_hdr_size;
@@ -88,7 +88,7 @@ void ArpRequest(void)
 	}
 
 	NetWriteIP(&arp->ar_tpa, NetArpWaitReplyIP);
-	NetSendPacket(NetTxPacket, eth_hdr_size + ARP_HDR_SIZE);
+	NetSendPacket(NetArpTxPacket, eth_hdr_size + ARP_HDR_SIZE);
 }
 
 void ArpTimeoutCheck(void)
@@ -196,11 +196,11 @@ void ArpReceive(struct ethernet_hdr *et, struct ip_udp_hdr *ip, int len)
 			net_get_arp_handler()((uchar *)arp, 0, reply_ip_addr,
 				0, len);
 
-			/* modify header, and transmit it */
-			memcpy(((struct ethernet_hdr *)NetArpWaitTxPacket)->
-				et_dest, &arp->ar_sha, ARP_HLEN);
-			NetSendPacket(NetArpWaitTxPacket,
-					NetArpWaitTxPacketSize);
+			/* set the mac address in the waiting packet's header
+			   and transmit it */
+			memcpy(((struct ethernet_hdr *)NetTxPacket)->et_dest,
+				&arp->ar_sha, ARP_HLEN);
+			NetSendPacket(NetTxPacket, NetArpWaitTxPacketSize);
 
 			/* no arp request pending now */
 			NetArpWaitPacketIP = 0;

net/arp.h

@@ -16,8 +16,6 @@
 extern IPaddr_t	NetArpWaitPacketIP;
 /* MAC address of waiting packet's destination */
 extern uchar *NetArpWaitPacketMAC;
-/* THE transmit packet */
-extern uchar *NetArpWaitTxPacket;
 extern int NetArpWaitTxPacketSize;
 extern ulong NetArpWaitTimerStart;
 extern int NetArpWaitTry;

net/net.c

@@ -442,6 +442,9 @@ restart:
 		 *	Abort if ctrl-c was pressed.
 		 */
 		if (ctrlc()) {
+			/* cancel any ARP that may not have completed */
+			NetArpWaitPacketIP = 0;
+
 			net_cleanup_loop();
 			eth_halt();
 			puts("\nAbort\n");
@@ -632,7 +635,6 @@ int NetSendUDPPacket(uchar *ether, IPaddr_t dest, int dport, int sport,
 		int payload_len)
 {
 	uchar *pkt;
-	int need_arp = 0;
 	int eth_hdr_size;
 	int pkt_hdr_size;
 
@@ -649,35 +651,21 @@ int NetSendUDPPacket(uchar *ether, IPaddr_t dest, int dport, int sport,
 	if (dest == 0xFFFFFFFF)
 		ether = NetBcastAddr;
 
-	/*
-	 * if MAC address was not discovered yet, save the packet and do
-	 * an ARP request
-	 */
-	if (memcmp(ether, NetEtherNullAddr, 6) == 0) {
-		need_arp = 1;
-		pkt = NetArpWaitTxPacket;
-	} else
-		pkt = (uchar *)NetTxPacket;
+	pkt = (uchar *)NetTxPacket;
 
 	eth_hdr_size = NetSetEther(pkt, ether, PROT_IP);
 	pkt += eth_hdr_size;
 	net_set_udp_header(pkt, dest, dport, sport, payload_len);
 	pkt_hdr_size = eth_hdr_size + IP_UDP_HDR_SIZE;
 
-	if (need_arp) {
+	/* if MAC address was not discovered yet, do an ARP request */
+	if (memcmp(ether, NetEtherNullAddr, 6) == 0) {
 		debug("sending ARP for %pI4\n", &dest);
 
 		/* save the ip and eth addr for the packet to send after arp */
 		NetArpWaitPacketIP = dest;
 		NetArpWaitPacketMAC = ether;
 
-		/*
-		 * Copy the packet data from the NetTxPacket into the
-		 *   NetArpWaitTxPacket to send after arp
-		 */
-		memcpy(pkt + IP_UDP_HDR_SIZE, (uchar *)NetTxPacket +
-			pkt_hdr_size, payload_len);
-
 		/* size of the waiting packet */
 		NetArpWaitTxPacketSize = pkt_hdr_size + payload_len;
 

net/ping.c

@@ -49,9 +49,8 @@ static int ping_send(void)
 
 	NetArpWaitPacketIP = NetPingIP;
 
-	eth_hdr_size = NetSetEther(NetArpWaitTxPacket, NetEtherNullAddr,
-		PROT_IP);
-	pkt = NetArpWaitTxPacket + eth_hdr_size;
+	eth_hdr_size = NetSetEther(NetTxPacket, NetEtherNullAddr, PROT_IP);
+	pkt = (uchar *)NetTxPacket + eth_hdr_size;
 
 	set_icmp_header(pkt, NetPingIP);