net/announce: Allow optional list of interfaces

Allow the caller to restrict the set of interfaces that announces are
sent on.  The default is still to send on all interfaces.

e.g.

  { "execute": "announce-self", "arguments": { "initial": 50, "max": 550, "rounds": 5, "step": 50, "interfaces": ["vn2", "vn1"] } }

This doesn't affect the behaviour of migraiton announcments.

Note: There's still only one timer for the qmp command, so that
performing an 'announce-self' on one list of interfaces followed
by another 'announce-self' on another list will stop the announces
on the existing set.

Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>

include/net/announce.h

@@ -22,7 +22,7 @@ struct AnnounceTimer {
 /* Returns: update the timer to the next time point */
 int64_t qemu_announce_timer_step(AnnounceTimer *timer);
 
-/* Delete the underlying timer */
+/* Delete the underlying timer and other data */
 void qemu_announce_timer_del(AnnounceTimer *timer);
 
 /*

net/announce.c

@@ -38,6 +38,8 @@ void qemu_announce_timer_del(AnnounceTimer *timer)
         timer_free(timer->tm);
         timer->tm = NULL;
     }
+    qapi_free_strList(timer->params.interfaces);
+    timer->params.interfaces = NULL;
 }
 
 /*
@@ -96,24 +98,47 @@ static int announce_self_create(uint8_t *buf,
 
 static void qemu_announce_self_iter(NICState *nic, void *opaque)
 {
+    AnnounceTimer *timer = opaque;
     uint8_t buf[60];
     int len;
+    bool skip;
+
+    if (timer->params.has_interfaces) {
+        strList *entry = timer->params.interfaces;
+        /* Skip unless we find our name in the requested list */
+        skip = true;
+
+        while (entry) {
+            if (!strcmp(entry->value, nic->ncs->name)) {
+                /* Found us */
+                skip = false;
+                break;
+            }
+            entry = entry->next;
+        }
+    } else {
+        skip = false;
+    }
+
+    trace_qemu_announce_self_iter(nic->ncs->name,
+                                  qemu_ether_ntoa(&nic->conf->macaddr), skip);
 
-    trace_qemu_announce_self_iter(qemu_ether_ntoa(&nic->conf->macaddr));
-    len = announce_self_create(buf, nic->conf->macaddr.a);
+    if (!skip) {
+        len = announce_self_create(buf, nic->conf->macaddr.a);
 
-    qemu_send_packet_raw(qemu_get_queue(nic), buf, len);
+        qemu_send_packet_raw(qemu_get_queue(nic), buf, len);
 
-    /* if the NIC provides it's own announcement support, use it as well */
-    if (nic->ncs->info->announce) {
-        nic->ncs->info->announce(nic->ncs);
+        /* if the NIC provides it's own announcement support, use it as well */
+        if (nic->ncs->info->announce) {
+            nic->ncs->info->announce(nic->ncs);
+        }
     }
 }
 static void qemu_announce_self_once(void *opaque)
 {
     AnnounceTimer *timer = (AnnounceTimer *)opaque;
 
-    qemu_foreach_nic(qemu_announce_self_iter, NULL);
+    qemu_foreach_nic(qemu_announce_self_iter, timer);
 
     if (--timer->round) {
         qemu_announce_timer_step(timer);

net/trace-events

@@ -1,7 +1,7 @@
 # See docs/devel/tracing.txt for syntax documentation.
 
 # announce.c
-qemu_announce_self_iter(const char *mac) "%s"
+qemu_announce_self_iter(const char *name, const char *mac, int skip) "%s:%s skip: %d"
 
 # vhost-user.c
 vhost_user_event(const char *chr, int event) "chr: %s got event: %d"

qapi/net.json

@@ -699,14 +699,18 @@
 #
 # @step: Delay increase (in ms) after each self-announcement attempt
 #
+# @interfaces: An optional list of interface names, which restricts the
+#        announcement to the listed interfaces. (Since 4.1)
+#
 # Since: 4.0
 ##
 
 { 'struct': 'AnnounceParameters',
   'data': { 'initial': 'int',
             'max': 'int',
             'rounds': 'int',
-            'step': 'int' } }
+            'step': 'int',
+            '*interfaces': ['str'] } }
 
 ##
 # @announce-self:
@@ -718,9 +722,10 @@
 #
 # Example:
 #
-# -> { "execute": "announce-self"
+# -> { "execute": "announce-self",
 #      "arguments": {
-#          "initial": 50, "max": 550, "rounds": 10, "step": 50 } }
+#          "initial": 50, "max": 550, "rounds": 10, "step": 50,
+#          "interfaces": ["vn2", "vn3"] } }
 # <- { "return": {} }
 #
 # Since: 4.0