[neighbour] Use discovery protocol field to identify incomplete neighbours

Use the discovery protocol pointer field (rather than the running
state of the discovery timer) to determine whether or not neighbour
discovery is ongoing, as a precursor to allowing the timer to be
(ab)used for adding deliberate latency to transmitted packets.

Signed-off-by: Michael Brown <mcb30@ipxe.org>

diff --git a/src/include/ipxe/neighbour.h b/src/include/ipxe/neighbour.h
index 1ca0ee33355a759c64219516bb27504db6430f60..7e7fac277e3ff4c8bfdc93b98a69a2e222109595 100644 (file)
--- a/src/include/ipxe/neighbour.h
+++ b/src/include/ipxe/neighbour.h
@@ -49,9 +49,9 @@ struct neighbour {
        /** Link-layer destination address */
        uint8_t ll_dest[MAX_LL_ADDR_LEN];
 
-       /** Neighbour discovery protocol (if any) */
+       /** Neighbour discovery protocol (if discovery is ongoing) */
        struct neighbour_discovery *discovery;
-       /** Network-layer source address (if any) */
+       /** Network-layer source address (for discovery requests) */
        uint8_t net_source[MAX_NET_ADDR_LEN];
        /** Retransmission timer */
        struct retry_timer timer;
@@ -60,17 +60,6 @@ struct neighbour {
        struct list_head tx_queue;
 };
 
-/**
- * Test if neighbour cache entry has a valid link-layer address
- *
- * @v neighbour                Neighbour cache entry
- * @ret has_ll_dest    Neighbour cache entry has a valid link-layer address
- */
-static inline __attribute__ (( always_inline )) int
-neighbour_has_ll_dest ( struct neighbour *neighbour ) {
-       return ( ! timer_running ( &neighbour->timer ) );
-}
-
 extern struct list_head neighbours;
 
 extern int neighbour_tx ( struct io_buffer *iobuf, struct net_device *netdev,

diff --git a/src/net/neighbour.c b/src/net/neighbour.c
index 253cdc0e6751ace3ee76ac491693cf8054faeed3..908f8e4b213766407e06d3f226e257999964f300 100644 (file)
--- a/src/net/neighbour.c
+++ b/src/net/neighbour.c
@@ -186,6 +186,9 @@ static void neighbour_discovered ( struct neighbour *neighbour,
        /* Stop retransmission timer */
        stop_timer ( &neighbour->timer );
 
+       /* Mark discovery as complete */
+       neighbour->discovery = NULL;
+
        /* Transmit any packets in queue.  Take out a temporary
         * reference on the entry to prevent it from going out of
         * scope during the call to net_tx().
@@ -300,6 +303,7 @@ int neighbour_tx ( struct io_buffer *iobuf, struct net_device *netdev,
                   struct neighbour_discovery *discovery,
                   const void *net_source ) {
        struct neighbour *neighbour;
+       int rc;
 
        /* Find or create neighbour cache entry */
        neighbour = neighbour_find ( netdev, net_protocol, net_dest );
@@ -310,19 +314,24 @@ int neighbour_tx ( struct io_buffer *iobuf, struct net_device *netdev,
                neighbour_discover ( neighbour, discovery, net_source );
        }
 
-       /* If a link-layer address is available then transmit
-        * immediately, otherwise queue for later transmission.
+       /* If discovery is still in progress then queue for later
+        * transmission.
         */
-       if ( neighbour_has_ll_dest ( neighbour ) ) {
-               return net_tx ( iobuf, netdev, net_protocol, neighbour->ll_dest,
-                               netdev->ll_addr );
-       } else {
+       if ( neighbour->discovery ) {
                DBGC2 ( neighbour, "NEIGHBOUR %s %s %s deferring packet\n",
                        netdev->name, net_protocol->name,
                        net_protocol->ntoa ( net_dest ) );
                list_add_tail ( &iobuf->list, &neighbour->tx_queue );
                return 0;
        }
+
+       /* Otherwise, transmit immediately */
+       if ( ( rc = net_tx ( iobuf, netdev, net_protocol, neighbour->ll_dest,
+                            netdev->ll_addr ) ) != 0 ) {
+               return rc;
+       }
+
+       return 0;
 }
 
 /**

diff --git a/src/usr/neighmgmt.c b/src/usr/neighmgmt.c
index 9fd88f82b79543d2bad0be0eb5a2fd19778589d9..fcdcbbfbbf57a05d1a8ead7e69c9aeb2de8d0490 100644 (file)
--- a/src/usr/neighmgmt.c
+++ b/src/usr/neighmgmt.c
@@ -50,9 +50,8 @@ void nstat ( void ) {
                printf ( "%s %s %s is %s %s", netdev->name, net_protocol->name,
                         net_protocol->ntoa ( neighbour->net_dest ),
                         ll_protocol->name,
-                        ( neighbour_has_ll_dest ( neighbour ) ?
-                          ll_protocol->ntoa ( neighbour->ll_dest ) :
-                          "(incomplete)" ) );
+                        ( neighbour->discovery ? "(incomplete)" :
+                          ll_protocol->ntoa ( neighbour->ll_dest ) ) );
                if ( neighbour->discovery )
                        printf ( " (%s)", neighbour->discovery->name );
                printf ( "\n" );