net: Don't overwrite waiting packets with asynchronous replies

Peter originally sent a fix, but it breaks a number of other things.
This addresses the original reported issue in a different way.

That report was:

> U-Boot has 1 common buffer to send Ethernet frames, pointed to by
> net_tx_packet.  When sending to an IP address without knowing the MAC
> address, U-Boot makes an ARP request (using the arp_tx_packet buffer)
> to find out the MAC address of the IP addressr. When a matching ARP
> reply is received, U-Boot continues sending the frame stored in the
> net_tx_packet buffer.
>
> However, in the mean time, if U-Boot needs to send out any network
> packets (e.g. replying ping packets or ARP requests for its own IP
> address etc.), it will use the net_tx_packet buffer to prepare the
> new packet. Thus this buffer is no longer the original packet meant
> to be transmitted after the ARP reply. The original packet will be
> lost.

This instead uses the ARP tx buffer to send async replies in the case
where we are actively waiting for an ARP reply.

Signed-off-by: Joe Hershberger <joe.hershberger@ni.com>

Reported-by: Tran Tien Dat <peter.trantiendat@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Tested-by: Bin Meng <bmeng.cn@gmail.com>

include/net.h

@@ -655,6 +655,14 @@ static inline void net_set_state(enum net_loop_state state)
 	net_state = state;
 }
 
+/*
+ * net_get_async_tx_pkt_buf - Get a packet buffer that is not in use for
+ *			      sending an asynchronous reply
+ *
+ * returns - ptr to packet buffer
+ */
+uchar * net_get_async_tx_pkt_buf(void);
+
 /* Transmit a packet */
 static inline void net_send_packet(uchar *pkt, int len)
 {

net/arp.c

@@ -34,8 +34,7 @@ uchar	       *arp_wait_packet_ethaddr;
 int		arp_wait_tx_packet_size;
 ulong		arp_wait_timer_start;
 int		arp_wait_try;
-
-static uchar   *arp_tx_packet;	/* THE ARP transmit packet */
+uchar	       *arp_tx_packet; /* THE ARP transmit packet */
 static uchar	arp_tx_packet_buf[PKTSIZE_ALIGN + PKTALIGN];
 
 void arp_init(void)
@@ -126,6 +125,7 @@ void arp_receive(struct ethernet_hdr *et, struct ip_udp_hdr *ip, int len)
 	struct arp_hdr *arp;
 	struct in_addr reply_ip_addr;
 	int eth_hdr_size;
+	uchar *tx_packet;
 
 	/*
 	 * We have to deal with two types of ARP packets:
@@ -182,8 +182,9 @@ void arp_receive(struct ethernet_hdr *et, struct ip_udp_hdr *ip, int len)
 		    (net_read_ip(&arp->ar_spa).s_addr & net_netmask.s_addr))
 			udelay(5000);
 #endif
-		memcpy(net_tx_packet, et, eth_hdr_size + ARP_HDR_SIZE);
-		net_send_packet(net_tx_packet, eth_hdr_size + ARP_HDR_SIZE);
+		tx_packet = net_get_async_tx_pkt_buf();
+		memcpy(tx_packet, et, eth_hdr_size + ARP_HDR_SIZE);
+		net_send_packet(tx_packet, eth_hdr_size + ARP_HDR_SIZE);
 		return;
 
 	case ARPOP_REPLY:		/* arp reply */

net/arp.h

@@ -20,6 +20,7 @@ extern uchar *arp_wait_packet_ethaddr;
 extern int arp_wait_tx_packet_size;
 extern ulong arp_wait_timer_start;
 extern int arp_wait_try;
+extern uchar *arp_tx_packet;
 
 void arp_init(void);
 void arp_request(void);

net/net.c

@@ -799,6 +799,14 @@ void net_set_timeout_handler(ulong iv, thand_f *f)
 	}
 }
 
+uchar *net_get_async_tx_pkt_buf(void)
+{
+	if (arp_is_waiting())
+		return arp_tx_packet; /* If we are waiting, we already sent */
+	else
+		return net_tx_packet;
+}
+
 int net_send_udp_packet(uchar *ether, struct in_addr dest, int dport, int sport,
 		int payload_len)
 {

net/ping.c

@@ -84,6 +84,7 @@ void ping_receive(struct ethernet_hdr *et, struct ip_udp_hdr *ip, int len)
 	struct icmp_hdr *icmph = (struct icmp_hdr *)&ip->udp_src;
 	struct in_addr src_ip;
 	int eth_hdr_size;
+	uchar *tx_packet;
 
 	switch (icmph->type) {
 	case ICMP_ECHO_REPLY:
@@ -107,8 +108,10 @@ void ping_receive(struct ethernet_hdr *et, struct ip_udp_hdr *ip, int len)
 		icmph->type = ICMP_ECHO_REPLY;
 		icmph->checksum = 0;
 		icmph->checksum = compute_ip_checksum(icmph, len - IP_HDR_SIZE);
-		memcpy(net_tx_packet, et, eth_hdr_size + len);
-		net_send_packet(net_tx_packet, eth_hdr_size + len);
+
+		tx_packet = net_get_async_tx_pkt_buf();
+		memcpy(tx_packet, et, eth_hdr_size + len);
+		net_send_packet(tx_packet, eth_hdr_size + len);
 		return;
 /*	default:
 		return;*/

test/dm/eth.c

@@ -332,10 +332,9 @@ static int dm_test_eth_async_arp_reply(struct unit_test_state *uts)
 	sandbox_eth_set_tx_handler(0, sb_with_async_arp_handler);
 	/* Used by all of the ut_assert macros in the tx_handler */
 	sandbox_eth_set_priv(0, uts);
-	sandbox_eth_skip_timeout();
 
 	env_set("ethact", "eth@10002000");
-	ut_assert(net_loop(PING) == -ETIMEDOUT);
+	ut_assertok(net_loop(PING));
 	ut_asserteq_str("eth@10002000", env_get("ethact"));
 
 	sandbox_eth_set_tx_handler(0, NULL);
@@ -418,10 +417,9 @@ static int dm_test_eth_async_ping_reply(struct unit_test_state *uts)
 	sandbox_eth_set_tx_handler(0, sb_with_async_ping_handler);
 	/* Used by all of the ut_assert macros in the tx_handler */
 	sandbox_eth_set_priv(0, uts);
-	sandbox_eth_skip_timeout();
 
 	env_set("ethact", "eth@10002000");
-	ut_assert(net_loop(PING) == -ETIMEDOUT);
+	ut_assertok(net_loop(PING));
 	ut_asserteq_str("eth@10002000", env_get("ethact"));
 
 	sandbox_eth_set_tx_handler(0, NULL);