ofproto-dpif-mirror: Always revalidate on mirror update.

Previously updating mirror settings would not trigger a revalidation,
this could result in impactful changes to mirrors taking a long time to
take effect.

This change sets need_revalidate whenever a setting is successfully set
on a mirror.

Fixes: ec7ceae ("ofproto-dpif: Modularize mirror code.")
Reported-at: https://issues.redhat.com/browse/FDP-788
Tested-by: Kevin Traynor <ktraynor@redhat.com>
Acked-by: Kevin Traynor <ktraynor@redhat.com>
Signed-off-by: Mike Pattrick <mkp@redhat.com>
Acked-by: Eelco Chaudron <echaudro@redhat.com>
Signed-off-by: Kevin Traynor <ktraynor@redhat.com>

ofproto/ofproto-dpif-mirror.c

@@ -265,7 +265,7 @@ mirror_set(struct mbridge *mbridge, void *aux, const char *name,
     {
         hmapx_destroy(&srcs_map);
         hmapx_destroy(&dsts_map);
-        return 0;
+        return ECANCELED;
     }
 
     /* XXX: Not sure if these need to be thread safe. */

ofproto/ofproto-dpif.c

@@ -3667,6 +3667,16 @@ mirror_set__(struct ofproto *ofproto_, void *aux,
                        s->n_dsts, s->src_vlans,
                        bundle_lookup(ofproto, s->out_bundle),
                        s->snaplen, s->out_vlan);
+
+    if (!error) {
+        ofproto->backer->need_revalidate = REV_RECONFIGURE;
+    } else if (error == ECANCELED) {
+        /* The user requested a change that is identical to the current state,
+         * the reconfiguration is canceled, but don't log an error message
+         * about that. */
+        error = 0;
+    }
+
     free(srcs);
     free(dsts);
     return error;