infra: fix mbuf leak when control input ring is full

post_to_stack() can fail if the control input ring is full. In several
places, the return value was ignored causing mbufs to leak silently.

Add __rte_warn_unused_result to post_to_stack() to catch future
occurrences at compile time. Check the return value at all call sites
and free the mbuf on error.

Signed-off-by: Robin Jarry <rjarry@redhat.com>
Reviewed-by: Christophe Fontaine <cfontain@redhat.com>

Author: rjarry

modules/infra/control/ctlplane.c

@@ -209,14 +209,18 @@ static void iface_cp_poll(evutil_socket_t, short reason, void *ev_iface) {
 
 	mbuf_data(mbuf)->iface = iface;
 
+	if (post_to_stack(iface_output, mbuf) < 0) {
+		LOG(ERR, "post_to_stack: %s", strerror(errno));
+		goto err;
+	}
+
 	stats = iface_get_stats(rte_lcore_id(), iface->id);
 	stats->cp_rx_packets += 1;
 	stats->cp_rx_bytes += rte_pktmbuf_pkt_len(mbuf);
 
 	if (gr_config.log_packets)
 		trace_log_packet(mbuf, "cp rx", iface->name);
 
-	post_to_stack(iface_output, mbuf);
 	return;
 
 err:

modules/infra/control/loopback.c

@@ -161,11 +161,15 @@ static void iface_loopback_poll(evutil_socket_t, short reason, void *ev_iface) {
 	e->iface = iface;
 	e->domain = ETH_DOMAIN_LOOPBACK;
 
+	if (post_to_stack(loopback_get_control_id(), mbuf) < 0) {
+		LOG(ERR, "post_to_stack: %s", strerror(errno));
+		goto err;
+	}
+
 	stats = iface_get_stats(rte_lcore_id(), iface->id);
 	stats->cp_rx_packets += 1;
 	stats->cp_rx_bytes += rte_pktmbuf_pkt_len(mbuf);
 
-	post_to_stack(loopback_get_control_id(), mbuf);
 	return;
 
 err:

modules/infra/datapath/gr_control_input.h

@@ -5,10 +5,12 @@
 
 #include <gr_mbuf.h>
 
+#include <rte_common.h>
+
 GR_MBUF_PRIV_DATA_TYPE(control_input_mbuf_data, { void *data; });
 
 typedef uint8_t control_input_t;
 
 control_input_t gr_control_input_register_handler(const char *node_name, bool data_is_mbuf);
 
-int post_to_stack(control_input_t type, void *data);
+__rte_warn_unused_result int post_to_stack(control_input_t type, void *data);

modules/ip/control/nexthop.c

@@ -206,7 +206,10 @@ void arp_probe_input_cb(void *obj, uintptr_t, const struct control_queue_drain *
 		o = ip_output_mbuf_data(held);
 		o->nh = nh;
 		o->iface = NULL;
-		post_to_stack(ip_output_node, held);
+		if (post_to_stack(ip_output_node, held) < 0) {
+			LOG(ERR, "post_to_stack: %s", strerror(errno));
+			rte_pktmbuf_free(held);
+		}
 		held = next;
 	}
 	l3->held_pkts_head = NULL;

modules/ip6/control/nexthop.c

@@ -249,7 +249,10 @@ void ndp_probe_input_cb(void *obj, uintptr_t, const struct control_queue_drain *
 		o = ip6_output_mbuf_data(held);
 		o->nh = nh;
 		o->iface = NULL;
-		post_to_stack(ip6_output_node, held);
+		if (post_to_stack(ip6_output_node, held) < 0) {
+			LOG(ERR, "post_to_stack: %s", strerror(errno));
+			rte_pktmbuf_free(held);
+		}
 		held = next;
 	}
 	l3->held_pkts_head = NULL;

modules/ip6/control/router_advert.c

@@ -180,7 +180,10 @@ static void send_ra_cb(evutil_socket_t, short /*what*/, void *priv) {
 		}
 		mbuf_data(m)->iface = iface;
 		build_ra_packet(m, &l3->ipv6);
-		post_to_stack(ra_output, m);
+		if (post_to_stack(ra_output, m) < 0) {
+			rte_pktmbuf_free(m);
+			LOG(ERR, "post_to_stack: %s", strerror(errno));
+		}
 	}
 }