net: icmp: Gracefully timeout net_buf get in RX path

If we are replying ICMPv{4|6} message, then do not wait forever
for a free buffer. In a busy system, this might lead to non-progress
in RX path if we receive lot of packet from the network and never get
a free buffer.

Change-Id: Iaef92541b8745f872a07bc6e2052d0393d4d1e8b
Signed-off-by: Jukka Rissanen <[email protected]>

subsys/net/ip/icmpv4.c

@@ -22,6 +22,8 @@
 #include "icmpv4.h"
 #include "net_stats.h"
 
+#define BUF_WAIT_TIME K_SECONDS(1)
+
 static inline enum net_verdict handle_echo_request(struct net_buf *buf)
 {
 	/* Note that we send the same data buffers back and just swap
@@ -179,17 +181,23 @@ int net_icmpv4_send_error(struct net_buf *orig, uint8_t type, uint8_t code)
 	struct net_if *iface = net_nbuf_iface(orig);
 	size_t extra_len, reserve;
 	struct in_addr addr, *src, *dst;
+	int err = -EIO;
 
 	if (NET_IPV4_BUF(orig)->proto == IPPROTO_ICMP) {
 		if (NET_ICMP_BUF(orig)->code < 8) {
 			/* We must not send ICMP errors back */
-			return -EINVAL;
+			err = -EINVAL;
+			goto drop_no_buf;
 		}
 	}
 
 	iface = net_nbuf_iface(orig);
 
-	buf = net_nbuf_get_reserve_tx(0, K_FOREVER);
+	buf = net_nbuf_get_reserve_tx(0, BUF_WAIT_TIME);
+	if (!buf) {
+		err = -ENOMEM;
+		goto drop_no_buf;
+	}
 
 	reserve = sizeof(struct net_ipv4_hdr) + sizeof(struct net_icmp_hdr) +
 		NET_ICMPV4_UNUSED_LEN;
@@ -220,8 +228,9 @@ int net_icmpv4_send_error(struct net_buf *orig, uint8_t type, uint8_t code)
 	/* We only copy minimal IPv4 + next header from original message.
 	 * This is so that the memory pressure is minimized.
 	 */
-	frag = net_nbuf_copy(orig, extra_len, reserve, K_FOREVER);
+	frag = net_nbuf_copy(orig, extra_len, reserve, BUF_WAIT_TIME);
 	if (!frag) {
+		err = -ENOMEM;
 		goto drop;
 	}
 
@@ -264,10 +273,12 @@ int net_icmpv4_send_error(struct net_buf *orig, uint8_t type, uint8_t code)
 
 drop:
 	net_nbuf_unref(buf);
+
+drop_no_buf:
 	net_stats_update_icmp_drop();
 
 	/* Note that we always return < 0 so that the caller knows to
 	 * discard the original buffer.
 	 */
-	return -EIO;
+	return err;
 }

subsys/net/ip/icmpv6.c

@@ -28,6 +28,8 @@
 #include "rpl.h"
 #endif
 
+#define BUF_WAIT_TIME K_SECONDS(1)
+
 static sys_slist_t handlers;
 
 void net_icmpv6_register_handler(struct net_icmpv6_handler *handler)
@@ -101,12 +103,15 @@ static enum net_verdict handle_echo_request(struct net_buf *orig)
 
 	iface = net_nbuf_iface(orig);
 
-	buf = net_nbuf_get_reserve_tx(0, K_FOREVER);
+	buf = net_nbuf_get_reserve_tx(0, BUF_WAIT_TIME);
+	if (!buf) {
+		goto drop_no_buf;
+	}
 
 	payload_len = sys_get_be16(NET_IPV6_BUF(orig)->len) -
 		sizeof(NET_ICMPH_LEN) - NET_ICMPV6_UNUSED_LEN;
 
-	frag = net_nbuf_copy_all(orig, 0, K_FOREVER);
+	frag = net_nbuf_copy_all(orig, 0, BUF_WAIT_TIME);
 	if (!frag) {
 		goto drop;
 	}
@@ -185,6 +190,8 @@ static enum net_verdict handle_echo_request(struct net_buf *orig)
 
 drop:
 	net_nbuf_unref(buf);
+
+drop_no_buf:
 	net_stats_update_icmp_drop();
 
 	return NET_DROP;
@@ -197,17 +204,23 @@ int net_icmpv6_send_error(struct net_buf *orig, uint8_t type, uint8_t code,
 	struct net_if *iface;
 	struct in6_addr *src, *dst;
 	size_t extra_len, reserve;
+	int err = -EIO;
 
 	if (NET_IPV6_BUF(orig)->nexthdr == IPPROTO_ICMPV6) {
 		if (NET_ICMP_BUF(orig)->code < 128) {
 			/* We must not send ICMP errors back */
-			return -EINVAL;
+			err = -EINVAL;
+			goto drop_no_buf;
 		}
 	}
 
 	iface = net_nbuf_iface(orig);
 
-	buf = net_nbuf_get_reserve_tx(0, K_FOREVER);
+	buf = net_nbuf_get_reserve_tx(0, BUF_WAIT_TIME);
+	if (!buf) {
+		err = -ENOMEM;
+		goto drop_no_buf;
+	}
 
 	/* We need to remember the original location of source and destination
 	 * addresses as the net_nbuf_copy() will mangle the original buffer.
@@ -241,8 +254,9 @@ int net_icmpv6_send_error(struct net_buf *orig, uint8_t type, uint8_t code,
 	/* We only copy minimal IPv6 + next header from original message.
 	 * This is so that the memory pressure is minimized.
 	 */
-	frag = net_nbuf_copy(orig, extra_len, reserve, K_FOREVER);
+	frag = net_nbuf_copy(orig, extra_len, reserve, BUF_WAIT_TIME);
 	if (!frag) {
+		err = -ENOMEM;
 		goto drop;
 	}
 
@@ -301,12 +315,14 @@ int net_icmpv6_send_error(struct net_buf *orig, uint8_t type, uint8_t code,
 
 drop:
 	net_nbuf_unref(buf);
+
+drop_no_buf:
 	net_stats_update_icmp_drop();
 
 	/* Note that we always return < 0 so that the caller knows to
 	 * discard the original buffer.
 	 */
-	return -EIO;
+	return err;
 }
 
 int net_icmpv6_send_echo_request(struct net_if *iface,