Index: if.c
===================================================================
RCS file: /cvs/src/sys/net/if.c,v
retrieving revision 1.615
diff -u -p -r1.615 if.c
--- if.c	22 Jul 2020 02:16:01 -0000	1.615
+++ if.c	23 Jul 2020 09:22:47 -0000
@@ -195,17 +195,20 @@ void if_map_dtor(void *, void *);
 struct ifnet *if_ref(struct ifnet *);
 
 /*
- * struct if_map
+ * union if_map
  *
  * bounded array of ifnet srp pointers used to fetch references of live
  * interfaces with if_get().
  */
 
-struct if_map {
-	unsigned long		 limit;
-	/* followed by limit ifnet srp pointers */
+union if_map {
+	unsigned int		 limit;
+	/* followed by limit-1 ifnet srp pointers */
+	struct srp		 srp;
 };
 
+#define IF_MAP_SRP(_if_map, _i)	(&(_if_map)[(_i)].srp)
+
 /*
  * struct if_idxmap
  *
@@ -281,19 +284,15 @@ struct ifnet_head ifnet = TAILQ_HEAD_INI
 void
 if_idxmap_init(unsigned int limit)
 {
-	struct if_map *if_map;
-	struct srp *map;
+	union if_map *if_map;
 	unsigned int i;
 
-	if_idxmap.serial = 1; /* skip ifidx 0 so it can return NULL */
-
-	if_map = malloc(sizeof(*if_map) + limit * sizeof(*map),
-	    M_IFADDR, M_WAITOK);
+	if_idxmap.serial = 1; /* skip ifidx 0 */
 
+	if_map = mallocarray(limit, sizeof(*if_map), M_IFADDR, M_WAITOK);
 	if_map->limit = limit;
-	map = (struct srp *)(if_map + 1);
-	for (i = 0; i < limit; i++)
-		srp_init(&map[i]);
+	for (i = 1; i < limit; i++)
+		srp_init(IF_MAP_SRP(if_map, i));
 
 	/* this is called early so there's nothing to race with */
 	srp_update_locked(&if_map_gc, &if_idxmap.map, if_map);
@@ -302,8 +301,7 @@ if_idxmap_init(unsigned int limit)
 void
 if_idxmap_insert(struct ifnet *ifp)
 {
-	struct if_map *if_map;
-	struct srp *map;
+	union if_map *if_map;
 	unsigned int index, i;
 
 	refcnt_init(&ifp->if_refcnt);
@@ -315,44 +313,41 @@ if_idxmap_insert(struct ifnet *ifp)
 		panic("too many interfaces");
 
 	if_map = srp_get_locked(&if_idxmap.map);
-	map = (struct srp *)(if_map + 1);
 
 	index = if_idxmap.serial++ & USHRT_MAX;
 
 	if (index >= if_map->limit) {
-		struct if_map *nif_map;
-		struct srp *nmap;
+		union if_map *nif_map;
 		unsigned int nlimit;
 		struct ifnet *nifp;
 
 		nlimit = if_map->limit * 2;
-		nif_map = malloc(sizeof(*nif_map) + nlimit * sizeof(*nmap),
+		nif_map = mallocarray(nlimit, sizeof(*nif_map),
 		    M_IFADDR, M_WAITOK);
-		nmap = (struct srp *)(nif_map + 1);
 
 		nif_map->limit = nlimit;
-		for (i = 0; i < if_map->limit; i++) {
-			srp_init(&nmap[i]);
-			nifp = srp_get_locked(&map[i]);
+		for (i = 1; i < if_map->limit; i++) {
+			srp_init(IF_MAP_SRP(nif_map, i));
+			nifp = srp_get_locked(IF_MAP_SRP(if_map, i));
 			if (nifp != NULL) {
-				srp_update_locked(&if_ifp_gc, &nmap[i],
-				    if_ref(nifp));
+				srp_update_locked(&if_ifp_gc,
+				    IF_MAP_SRP(nif_map, i), if_ref(nifp));
 			}
 		}
 
 		while (i < nlimit) {
-			srp_init(&nmap[i]);
+			srp_init(IF_MAP_SRP(nif_map, i));
 			i++;
 		}
 
 		srp_update_locked(&if_map_gc, &if_idxmap.map, nif_map);
 		if_map = nif_map;
-		map = nmap;
 	}
 
 	/* pick the next free index */
-	for (i = 0; i < USHRT_MAX; i++) {
-		if (index != 0 && srp_get_locked(&map[index]) == NULL)
+	for (i = 1; i < USHRT_MAX; i++) {
+		if (index != 0 &&
+		    srp_get_locked(IF_MAP_SRP(if_map, index)) == NULL)
 			break;
 
 		index = if_idxmap.serial++ & USHRT_MAX;
@@ -360,14 +355,13 @@ if_idxmap_insert(struct ifnet *ifp)
 
 	/* commit */
 	ifp->if_index = index;
-	srp_update_locked(&if_ifp_gc, &map[index], if_ref(ifp));
+	srp_update_locked(&if_ifp_gc, IF_MAP_SRP(if_map, index), if_ref(ifp));
 }
 
 void
 if_idxmap_remove(struct ifnet *ifp)
 {
-	struct if_map *if_map;
-	struct srp *map;
+	union if_map *if_map;
 	unsigned int index;
 
 	index = ifp->if_index;
@@ -378,10 +372,9 @@ if_idxmap_remove(struct ifnet *ifp)
 	if_map = srp_get_locked(&if_idxmap.map);
 	KASSERT(index < if_map->limit);
 
-	map = (struct srp *)(if_map + 1);
-	KASSERT(ifp == (struct ifnet *)srp_get_locked(&map[index]));
+	KASSERT(ifp == srp_get_locked(IF_MAP_SRP(if_map, index)));
 
-	srp_update_locked(&if_ifp_gc, &map[index], NULL);
+	srp_update_locked(&if_ifp_gc, IF_MAP_SRP(if_map, index), NULL);
 	if_idxmap.count--;
 	/* end of if_idxmap modifications */
 
@@ -398,18 +391,17 @@ if_ifp_dtor(void *null, void *ifp)
 void
 if_map_dtor(void *null, void *m)
 {
-	struct if_map *if_map = m;
-	struct srp *map = (struct srp *)(if_map + 1);
+	union if_map *if_map = m;
 	unsigned int i;
 
 	/*
 	 * dont need to serialize the use of update_locked since this is
 	 * the last reference to this map. there's nothing to race against.
 	 */
-	for (i = 0; i < if_map->limit; i++)
-		srp_update_locked(&if_ifp_gc, &map[i], NULL);
+	for (i = 1; i < if_map->limit; i++)
+		srp_update_locked(&if_ifp_gc, IF_MAP_SRP(if_map, i), NULL);
 
-	free(if_map, M_IFADDR, sizeof(*if_map) + if_map->limit * sizeof(*map));
+	free(if_map, M_IFADDR, sizeof(*if_map) * if_map->limit);
 }
 
 /*
@@ -1660,15 +1652,15 @@ struct ifnet *
 if_get(unsigned int index)
 {
 	struct srp_ref sr;
-	struct if_map *if_map;
-	struct srp *map;
+	union if_map *if_map;
 	struct ifnet *ifp = NULL;
 
+	if (index == 0)
+		return (NULL);
+
 	if_map = srp_enter(&sr, &if_idxmap.map);
 	if (index < if_map->limit) {
-		map = (struct srp *)(if_map + 1);
-
-		ifp = srp_follow(&sr, &map[index]);
+		ifp = srp_follow(&sr, IF_MAP_SRP(if_map, index));
 		if (ifp != NULL) {
 			KASSERT(ifp->if_index == index);
 			if_ref(ifp);