net/colo-compare.c: Expose compare "max_queue_size" to users

This patch allow users to set the "max_queue_size" according
to their environment.

Signed-off-by: Zhang Chen <chen.zhang@intel.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>

net/colo-compare.c

@@ -59,6 +59,7 @@ static bool colo_compare_active;
 static QemuMutex event_mtx;
 static QemuCond event_complete_cond;
 static int event_unhandled_count;
+static uint32_t max_queue_size;
 
 /*
  *  + CompareState ++
@@ -222,7 +223,7 @@ static void fill_pkt_tcp_info(void *data, uint32_t *max_ack)
  */
 static int colo_insert_packet(GQueue *queue, Packet *pkt, uint32_t *max_ack)
 {
-    if (g_queue_get_length(queue) <= MAX_QUEUE_SIZE) {
+    if (g_queue_get_length(queue) <= max_queue_size) {
         if (pkt->ip->ip_p == IPPROTO_TCP) {
             fill_pkt_tcp_info(pkt, max_ack);
             g_queue_insert_sorted(queue,
@@ -1134,6 +1135,37 @@ static void compare_set_expired_scan_cycle(Object *obj, Visitor *v,
     s->expired_scan_cycle = value;
 }
 
+static void get_max_queue_size(Object *obj, Visitor *v,
+                               const char *name, void *opaque,
+                               Error **errp)
+{
+    uint32_t value = max_queue_size;
+
+    visit_type_uint32(v, name, &value, errp);
+}
+
+static void set_max_queue_size(Object *obj, Visitor *v,
+                               const char *name, void *opaque,
+                               Error **errp)
+{
+    Error *local_err = NULL;
+    uint32_t value;
+
+    visit_type_uint32(v, name, &value, &local_err);
+    if (local_err) {
+        goto out;
+    }
+    if (!value) {
+        error_setg(&local_err, "Property '%s.%s' requires a positive value",
+                   object_get_typename(obj), name);
+        goto out;
+    }
+    max_queue_size = value;
+
+out:
+    error_propagate(errp, local_err);
+}
+
 static void compare_pri_rs_finalize(SocketReadState *pri_rs)
 {
     CompareState *s = container_of(pri_rs, CompareState, pri_rs);
@@ -1251,6 +1283,11 @@ static void colo_compare_complete(UserCreatable *uc, Error **errp)
         s->expired_scan_cycle = REGULAR_PACKET_CHECK_MS;
     }
 
+    if (!max_queue_size) {
+        /* Set default queue size to 1024 */
+        max_queue_size = MAX_QUEUE_SIZE;
+    }
+
     if (find_and_check_chardev(&chr, s->pri_indev, errp) ||
         !qemu_chr_fe_init(&s->chr_pri_in, chr, errp)) {
         return;
@@ -1370,6 +1407,10 @@ static void colo_compare_init(Object *obj)
                         compare_get_expired_scan_cycle,
                         compare_set_expired_scan_cycle, NULL, NULL);
 
+    object_property_add(obj, "max_queue_size", "uint32",
+                        get_max_queue_size,
+                        set_max_queue_size, NULL, NULL);
+
     s->vnet_hdr = false;
     object_property_add_bool(obj, "vnet_hdr_support", compare_get_vnet_hdr,
                              compare_set_vnet_hdr);

qemu-options.hx

@@ -4695,7 +4695,7 @@ SRST
         stored. The file format is libpcap, so it can be analyzed with
         tools such as tcpdump or Wireshark.
 
-    ``-object colo-compare,id=id,primary_in=chardevid,secondary_in=chardevid,outdev=chardevid,iothread=id[,vnet_hdr_support][,notify_dev=id][,compare_timeout=@var{ms}][,expired_scan_cycle=@var{ms}``
+    ``-object colo-compare,id=id,primary_in=chardevid,secondary_in=chardevid,outdev=chardevid,iothread=id[,vnet_hdr_support][,notify_dev=id][,compare_timeout=@var{ms}][,expired_scan_cycle=@var{ms}][,max_queue_size=@var{size}]``
         Colo-compare gets packet from primary\_inchardevid and
         secondary\_inchardevid, than compare primary packet with
         secondary packet. If the packets are same, we will output
@@ -4707,7 +4707,8 @@ SRST
         vnet\_hdr\_len. Then compare\_timeout=@var{ms} determines the
         maximum delay colo-compare wait for the packet.
         The expired\_scan\_cycle=@var{ms} to set the period of scanning
-        expired primary node network packets.
+        expired primary node network packets. The max\_queue\_size=@var{size}
+        is to set the max compare queue size depend on user environment.
         If you want to use Xen COLO, will need the notify\_dev to
         notify Xen colo-frame to do checkpoint.