[PATCH v4 2/2] net/colo-compare.c: handling of the full primary or secondary queue

[Derek Su]

The pervious handling of the full primary or queue is only dropping
the packet. If there are lots of clients to the guest VM,
the "drop" will lead to the lost of the networking connection
until next checkpoint.

To address the issue, this patch drops the packet firstly.
Then, do checkpoint and flush packets.

Signed-off-by: Derek Su <address@hidden>
---
 net/colo-compare.c | 39 ++++++++++++++++++++++++++++-----------
 1 file changed, 28 insertions(+), 11 deletions(-)

diff --git a/net/colo-compare.c b/net/colo-compare.c
index cdd87b2aa8..fe8779cf2d 100644
--- a/net/colo-compare.c
+++ b/net/colo-compare.c
@@ -125,6 +125,12 @@ static const char *colo_mode[] = {
     [SECONDARY_IN] = "secondary",
 };
 
+enum {
+    QUEUE_INSERT_ERR = -1,
+    QUEUE_INSERT_OK = 0,
+    QUEUE_INSERT_FULL = 1,
+};
+
 static int compare_chr_send(CompareState *s,
                             const uint8_t *buf,
                             uint32_t size,
@@ -211,8 +217,10 @@ static int colo_insert_packet(GQueue *queue, Packet *pkt, 
uint32_t *max_ack)
 }
 
 /*
- * Return 0 on success, if return -1 means the pkt
- * is unsupported(arp and ipv6) and will be sent later
+ * Return QUEUE_INSERT_OK on success.
+ * If return QUEUE_INSERT_FULL means list is full, and
+ * QUEUE_INSERT_ERR means the pkt is unsupported(arp and ipv6) and
+ * will be sent later
  */
 static int packet_enqueue(CompareState *s, int mode, Connection **con)
 {
@@ -234,7 +242,7 @@ static int packet_enqueue(CompareState *s, int mode, 
Connection **con)
     if (parse_packet_early(pkt)) {
         packet_destroy(pkt, NULL);
         pkt = NULL;
-        return -1;
+        return QUEUE_INSERT_ERR;
     }
     fill_connection_key(pkt, &key);
 
@@ -258,11 +266,12 @@ static int packet_enqueue(CompareState *s, int mode, 
Connection **con)
                      "drop packet", colo_mode[mode]);
         packet_destroy(pkt, NULL);
         pkt = NULL;
+        return QUEUE_INSERT_FULL;
     }
 
     *con = conn;
 
-    return 0;
+    return QUEUE_INSERT_OK;
 }
 
 static inline bool after(uint32_t seq1, uint32_t seq2)
@@ -995,17 +1004,21 @@ static void compare_pri_rs_finalize(SocketReadState 
*pri_rs)
 {
     CompareState *s = container_of(pri_rs, CompareState, pri_rs);
     Connection *conn = NULL;
+    int ret;
 
-    if (packet_enqueue(s, PRIMARY_IN, &conn)) {
+    ret = packet_enqueue(s, PRIMARY_IN, &conn);
+    if (ret == QUEUE_INSERT_OK) {
+        /* compare packet in the specified connection */
+        colo_compare_connection(conn, s);
+    } else if (ret == QUEUE_INSERT_FULL) {
+        colo_compare_inconsistency_notify(s);
+    } else {
         trace_colo_compare_main("primary: unsupported packet in");
         compare_chr_send(s,
                          pri_rs->buf,
                          pri_rs->packet_len,
                          pri_rs->vnet_hdr_len,
                          false);
-    } else {
-        /* compare packet in the specified connection */
-        colo_compare_connection(conn, s);
     }
 }
 
@@ -1013,12 +1026,16 @@ static void compare_sec_rs_finalize(SocketReadState 
*sec_rs)
 {
     CompareState *s = container_of(sec_rs, CompareState, sec_rs);
     Connection *conn = NULL;
+    int ret;
 
-    if (packet_enqueue(s, SECONDARY_IN, &conn)) {
-        trace_colo_compare_main("secondary: unsupported packet in");
-    } else {
+    ret = packet_enqueue(s, SECONDARY_IN, &conn);
+    if (ret == QUEUE_INSERT_OK) {
         /* compare packet in the specified connection */
         colo_compare_connection(conn, s);
+    } else if (ret == QUEUE_INSERT_FULL) {
+        colo_compare_inconsistency_notify(s);
+    } else {
+        trace_colo_compare_main("secondary: unsupported packet in");
     }
 }
 
-- 
2.17.1