net: dhcp: correct timeout scheduling with multiple interfaces

If there are multiple interfaces a change to the timeout for one
cannot determine the correct delay until the next timeout event.  That
can be determined only by checking for the next event over all
interfaces, which is exactly what's done by the timeout worker.

Refactor interface timeout configuration to just set the start time
and request time, and trigger the worker to calculate the next
scheduled event.

Signed-off-by: Peter Bigot <[email protected]>

Author: pabigot

subsys/net/ip/dhcpv4.c

@@ -276,6 +276,28 @@ static struct net_pkt *dhcpv4_create_message(struct net_if *iface, uint8_t type,
 	return NULL;
 }
 
+static void dhcpv4_immediate_timeout(struct net_if_dhcpv4 *dhcpv4)
+{
+	NET_DBG("force timeout dhcpv4=%p", dhcpv4);
+	dhcpv4->timer_start = k_uptime_get() - 1;
+	dhcpv4->request_time = 0U;
+	k_delayed_work_submit(&timeout_work, K_NO_WAIT);
+}
+
+static void dhcpv4_set_timeout(struct net_if_dhcpv4 *dhcpv4,
+			       uint32_t timeout)
+{
+	NET_DBG("sched timeout dhcvp4=%p timeout=%us", dhcpv4, timeout);
+	dhcpv4->timer_start = k_uptime_get();
+	dhcpv4->request_time = timeout;
+
+	/* NB: This interface may not be providing the next timeout
+	 * event; also this timeout may replace the current timeout
+	 * event.  Delegate scheduling to the timeout manager.
+	 */
+	k_delayed_work_submit(&timeout_work, K_NO_WAIT);
+}
+
 static uint32_t dhcpv4_update_message_timeout(struct net_if_dhcpv4 *dhcpv4)
 {
 	uint32_t timeout;
@@ -291,8 +313,7 @@ static uint32_t dhcpv4_update_message_timeout(struct net_if_dhcpv4 *dhcpv4)
 	timeout += (sys_rand32_get() % 3U) - 1;
 
 	dhcpv4->attempts++;
-	dhcpv4->timer_start = k_uptime_get();
-	dhcpv4->request_time = timeout;
+	dhcpv4_set_timeout(dhcpv4, timeout);
 
 	return timeout;
 }
@@ -419,11 +440,6 @@ static uint32_t dhcpv4_send_discover(struct net_if *iface)
 			DHCPV4_INITIAL_DELAY_MIN;
 }
 
-static void dhcpv4_update_timeout_work(uint32_t timeout)
-{
-	k_delayed_work_submit(&timeout_work, K_SECONDS(timeout));
-}
-
 static void dhcpv4_enter_selecting(struct net_if *iface)
 {
 	struct in_addr any = INADDR_ANY_INIT;
@@ -505,7 +521,7 @@ static void dhcpv4_enter_requesting(struct net_if *iface)
 	NET_DBG("enter state=%s",
 		net_dhcpv4_state_name(iface->config.dhcpv4.state));
 
-	dhcpv4_update_timeout_work(dhcpv4_send_request(iface));
+	dhcpv4_send_request(iface);
 }
 
 static void dhcpv4_enter_bound(struct net_if *iface)
@@ -532,10 +548,8 @@ static void dhcpv4_enter_bound(struct net_if *iface)
 		net_dhcpv4_state_name(iface->config.dhcpv4.state),
 		renewal_time, rebinding_time);
 
-	iface->config.dhcpv4.timer_start = k_uptime_get();
-	iface->config.dhcpv4.request_time = MIN(renewal_time, rebinding_time);
-
-	dhcpv4_update_timeout_work(iface->config.dhcpv4.request_time);
+	dhcpv4_set_timeout(&iface->config.dhcpv4,
+			   MIN(renewal_time, rebinding_time));
 
 	net_mgmt_event_notify_with_info(NET_EVENT_IPV4_DHCP_BOUND, iface,
 					&iface->config.dhcpv4,
@@ -546,7 +560,8 @@ static uint32_t dhcpv4_manage_timers(struct net_if *iface, int64_t now)
 {
 	uint32_t timeleft = dhcpv4_request_timeleft(iface, now);
 
-	NET_DBG("iface %p state=%s timeleft=%u", iface,
+	NET_DBG("iface %p dhcpv4=%p state=%s timeleft=%u", iface,
+		&iface->config.dhcpv4,
 		net_dhcpv4_state_name(iface->config.dhcpv4.state), timeleft);
 
 	if (timeleft != 0U) {
@@ -1083,11 +1098,7 @@ static void dhcpv4_iface_event_handler(struct net_mgmt_event_callback *cb,
 		 * enough. Instead we can force a request timeout
 		 * which will then call dhcpv4_send_request() automatically.
 		 */
-		iface->config.dhcpv4.timer_start = k_uptime_get() - 1;
-		iface->config.dhcpv4.request_time = 0U;
-
-		k_delayed_work_cancel(&timeout_work);
-		k_delayed_work_submit(&timeout_work, K_NO_WAIT);
+		dhcpv4_immediate_timeout(&iface->config.dhcpv4);
 	}
 }
 
@@ -1151,10 +1162,7 @@ void net_dhcpv4_start(struct net_if *iface)
 		sys_slist_append(&dhcpv4_ifaces,
 				 &iface->config.dhcpv4.node);
 
-		iface->config.dhcpv4.timer_start = k_uptime_get();
-		iface->config.dhcpv4.request_time = timeout;
-
-		dhcpv4_update_timeout_work(timeout);
+		dhcpv4_set_timeout(&iface->config.dhcpv4, timeout);
 
 		break;
 	case NET_DHCPV4_INIT: