sd-radv: voidify sd_radv_remove_prefix()

If the prefix is only referenced by sd_radv, then the returned pointer
is already freed.

networkd does not uses the returned value. Let's voidify the function.

src/libsystemd-network/sd-radv.c

@@ -659,15 +659,20 @@ int sd_radv_add_prefix(sd_radv *ra, sd_radv_prefix *p) {
         return 0;
 }
 
-sd_radv_prefix *sd_radv_remove_prefix(sd_radv *ra,
-                                               const struct in6_addr *prefix,
-                                               unsigned char prefixlen) {
-        sd_radv_prefix *cur, *next;
+void sd_radv_remove_prefix(
+                sd_radv *ra,
+                const struct in6_addr *prefix,
+                unsigned char prefixlen) {
 
-        assert_return(ra, NULL);
-        assert_return(prefix, NULL);
+        sd_radv_prefix *cur;
 
-        LIST_FOREACH_SAFE(prefix, cur, next, ra->prefixes) {
+        if (!ra)
+                return;
+
+        if (!prefix)
+                return;
+
+        LIST_FOREACH(prefix, cur, ra->prefixes) {
                 if (prefixlen != cur->opt.prefixlen)
                         continue;
 
@@ -677,11 +682,8 @@ sd_radv_prefix *sd_radv_remove_prefix(sd_radv *ra,
                 LIST_REMOVE(prefix, ra->prefixes, cur);
                 ra->n_prefixes--;
                 sd_radv_prefix_unref(cur);
-
-                break;
+                return;
         }
-
-        return cur;
 }
 
 int sd_radv_add_route_prefix(sd_radv *ra, sd_radv_route_prefix *p) {

src/network/networkd-dhcp-prefix-delegation.c

@@ -187,7 +187,7 @@ int dhcp_pd_remove(Link *link, bool only_marked) {
                                 continue;
 
                         if (link->radv)
-                                (void) sd_radv_remove_prefix(link->radv, &route->dst.in6, 64);
+                                sd_radv_remove_prefix(link->radv, &route->dst.in6, 64);
 
                         link_remove_dhcp_pd_subnet_prefix(link, &route->dst.in6);
 
@@ -212,7 +212,7 @@ int dhcp_pd_remove(Link *link, bool only_marked) {
                         in6_addr_mask(&prefix, 64);
 
                         if (link->radv)
-                                (void) sd_radv_remove_prefix(link->radv, &prefix, 64);
+                                sd_radv_remove_prefix(link->radv, &prefix, 64);
 
                         link_remove_dhcp_pd_subnet_prefix(link, &prefix);
 

src/systemd/sd-radv.h

@@ -59,8 +59,7 @@ int sd_radv_set_other_information(sd_radv *ra, int other);
 int sd_radv_set_preference(sd_radv *ra, unsigned preference);
 int sd_radv_add_prefix(sd_radv *ra, sd_radv_prefix *p);
 int sd_radv_add_route_prefix(sd_radv *ra, sd_radv_route_prefix *p);
-sd_radv_prefix *sd_radv_remove_prefix(sd_radv *ra, const struct in6_addr *prefix,
-                                      unsigned char prefixlen);
+void sd_radv_remove_prefix(sd_radv *ra, const struct in6_addr *prefix, unsigned char prefixlen);
 int sd_radv_set_rdnss(sd_radv *ra, uint32_t lifetime,
                       const struct in6_addr *dns, size_t n_dns);
 int sd_radv_set_dnssl(sd_radv *ra, uint32_t lifetime, char **search_list);