net/iface: Coalesce all RS timers through one

This reduces the size of struct net_if_ipv6 by 24 bytes by moving
the k_delayed_work attribute into net_if core code.
Then each net_if_ipv6 can be added to the timer handler via a slist.

This does not make much gain if the system has only 1 network interface
It starts to be interesting if it has 2+ network interfaces then.

Fixes #8728

Signed-off-by: Tomasz Bursztyka <tomasz.bursztyka@linux.intel.com>

include/net/net_if.h

@@ -220,9 +220,6 @@ struct net_if_ipv6 {
 	/** Prefixes */
 	struct net_if_ipv6_prefix prefix[NET_IF_MAX_IPV6_PREFIX];
 
-	/** Router solicitation timer */
-	struct k_delayed_work rs_timer;
-
 	/** Default reachable time (RFC 4861, page 52) */
 	u32_t base_reachable_time;
 
@@ -231,12 +228,19 @@ struct net_if_ipv6 {
 
 	/** Retransmit timer (RFC 4861, page 52) */
 	u32_t retrans_timer;
+#if defined(CONFIG_NET_IPV6_ND)
+	/** Router solicitation timer node */
+	sys_snode_t rs_node;
 
-	/** IPv6 hop limit */
-	u8_t hop_limit;
+	/* RS start time */
+	u32_t rs_start;
 
 	/** RS count */
 	u8_t rs_count;
+#endif
+
+	/** IPv6 hop limit */
+	u8_t hop_limit;
 };
 
 /** @cond INTERNAL_HIDDEN */
@@ -659,6 +663,21 @@ static inline void net_if_start_dad(struct net_if *iface)
  */
 void net_if_start_rs(struct net_if *iface);
 
+
+/**
+ * @brief Stop neighbor discovery.
+ *
+ * @param iface Pointer to a network interface structure
+ */
+#if defined(CONFIG_NET_IPV6_ND)
+void net_if_stop_rs(struct net_if *iface);
+#else
+static inline void net_if_stop_rs(struct net_if *iface)
+{
+	ARG_UNUSED(iface);
+}
+#endif /* CONFIG_NET_IPV6_ND */
+
 /**
  * @brief Set a network interface's link address
  *

subsys/net/ip/ipv6_nbr.c

@@ -2429,7 +2429,7 @@ static enum net_verdict handle_ra_input(struct net_pkt *pkt,
 	}
 
 	/* Cancel the RS timer on iface */
-	k_delayed_work_cancel(&net_pkt_iface(pkt)->config.ip.ipv6->rs_timer);
+	net_if_stop_rs(net_pkt_iface(pkt));
 
 	net_pkt_unref(pkt);
 

subsys/net/ip/net_if.c

@@ -65,6 +65,11 @@ static struct k_delayed_work dad_timer;
 static sys_slist_t active_dad_timers;
 #endif
 
+#if defined(CONFIG_NET_IPV6_ND)
+static struct k_delayed_work rs_timer;
+static sys_slist_t active_rs_timers;
+#endif
+
 static struct {
 	struct net_if_ipv6 ipv6;
 	struct net_if *iface;
@@ -742,30 +747,49 @@ static inline void net_if_ipv6_start_dad(struct net_if *iface,
 
 static void rs_timeout(struct k_work *work)
 {
-	/* Did not receive RA yet. */
-	struct net_if_ipv6 *ipv6 = CONTAINER_OF(work,
-						struct net_if_ipv6,
-						rs_timer);
+	u32_t current_time = k_uptime_get_32();
+	struct net_if_ipv6 *ipv6, *next;
+
+	ARG_UNUSED(work);
+
+	SYS_SLIST_FOR_EACH_CONTAINER_SAFE(&active_rs_timers,
+					  ipv6, next, rs_node) {
 		struct net_if *iface;
 
+		if ((s32_t)(ipv6->rs_start + RS_TIMEOUT - current_time) > 0) {
+			break;
+		}
+
+		/* Removing the ipv6 from active_rs_timers list */
+		sys_slist_remove(&active_rs_timers, NULL, &ipv6->rs_node);
+
+		/* Did not receive RA yet. */
 		ipv6->rs_count++;
 
 		for (iface = __net_if_start; iface != __net_if_end; iface++) {
 			if (iface->config.ip.ipv6 == ipv6) {
-			goto found;
+				break;
 			}
 		}
 
-	NET_DBG("Interface IPv6 config %p not found", ipv6);
-	return;
-
-found:
-	NET_DBG("RS no respond iface %p count %d", iface,
-		ipv6->rs_count);
-
+		if (iface != __net_if_end) {
+			NET_DBG("RS no respond iface %p count %d",
+				iface, ipv6->rs_count);
 			if (ipv6->rs_count < RS_COUNT) {
 				net_if_start_rs(iface);
 			}
+		} else {
+			NET_DBG("Interface IPv6 config %p not found", ipv6);
+		}
+
+		ipv6 = NULL;
+	}
+
+	if (ipv6) {
+		k_delayed_work_submit(&rs_timer,
+				      ipv6->rs_start +
+				      RS_TIMEOUT - current_time);
+	}
 }
 
 void net_if_start_rs(struct net_if *iface)
@@ -779,17 +803,37 @@ void net_if_start_rs(struct net_if *iface)
 	NET_DBG("Starting ND/RS for iface %p", iface);
 
 	if (!net_ipv6_start_rs(iface)) {
-		k_delayed_work_submit(&ipv6->rs_timer, RS_TIMEOUT);
+		ipv6->rs_start = k_uptime_get_32();
+		sys_slist_append(&active_rs_timers, &ipv6->rs_node);
+
+		if (!k_delayed_work_remaining_get(&rs_timer)) {
+			k_delayed_work_submit(&rs_timer, RS_TIMEOUT);
+		}
 	}
 }
 
-static inline void iface_ipv6_nd_init(struct net_if_ipv6 *ipv6)
+void net_if_stop_rs(struct net_if *iface)
 {
-	k_delayed_work_init(&ipv6->rs_timer, rs_timeout);
+	struct net_if_ipv6 *ipv6 = iface->config.ip.ipv6;
+
+	if (!ipv6) {
+		return;
+	}
+
+	NET_DBG("Stopping ND/RS for iface %p", iface);
+
+	sys_slist_find_and_remove(&active_rs_timers, &ipv6->rs_node);
+}
+
+static inline void iface_ipv6_nd_init(void)
+{
+	k_delayed_work_init(&rs_timer, rs_timeout);
+	sys_slist_init(&active_rs_timers);
 }
 
 #else
 #define net_if_start_rs(...)
+#define net_if_stop_rs(...)
 #define iface_ipv6_nd_init(...)
 #endif /* CONFIG_NET_IPV6_ND */
 
@@ -2207,6 +2251,7 @@ static void iface_ipv6_init(int if_count)
 	int i;
 
 	iface_ipv6_dad_init();
+	iface_ipv6_nd_init();
 
 	k_delayed_work_init(&address_lifetime_timer, address_lifetime_timeout);
 	k_delayed_work_init(&prefix_lifetime_timer, prefix_lifetime_timeout);
@@ -2224,8 +2269,6 @@ static void iface_ipv6_init(int if_count)
 		ipv6_addresses[i].ipv6.base_reachable_time = REACHABLE_TIME;
 
 		net_if_ipv6_set_reachable_time(&ipv6_addresses[i].ipv6);
-
-		iface_ipv6_nd_init(&ipv6_addresses[i].ipv6);
 	}
 }