migration: poll the cm event while wait RDMA work request completion

If the peer qemu is crashed, the qemu_rdma_wait_comp_channel function
maybe loop forever. so we should also poll the cm event fd, and when
receive RDMA_CM_EVENT_DISCONNECTED and RDMA_CM_EVENT_DEVICE_REMOVAL,
we consider some error happened.

Signed-off-by: Lidong Chen <[email protected]>
Signed-off-by: Gal Shachaf <[email protected]>
Signed-off-by: Aviad Yehezkel <[email protected]>
Reviewed-by: Dr. David Alan Gilbert <[email protected]>
Reviewed-by: Juan Quintela <[email protected]>
Signed-off-by: Juan Quintela <[email protected]>

Author: jemmy858585

migration/rdma.c

@@ -1489,6 +1489,9 @@ static uint64_t qemu_rdma_poll(RDMAContext *rdma, uint64_t *wr_id_out,
  */
 static int qemu_rdma_wait_comp_channel(RDMAContext *rdma)
 {
+    struct rdma_cm_event *cm_event;
+    int ret = -1;
+
     /*
      * Coroutine doesn't start until migration_fd_process_incoming()
      * so don't yield unless we know we're running inside of a coroutine.
@@ -1505,13 +1508,37 @@ static int qemu_rdma_wait_comp_channel(RDMAContext *rdma)
          * without hanging forever.
          */
         while (!rdma->error_state  && !rdma->received_error) {
-            GPollFD pfds[1];
+            GPollFD pfds[2];
             pfds[0].fd = rdma->comp_channel->fd;
             pfds[0].events = G_IO_IN | G_IO_HUP | G_IO_ERR;
+            pfds[0].revents = 0;
+
+            pfds[1].fd = rdma->channel->fd;
+            pfds[1].events = G_IO_IN | G_IO_HUP | G_IO_ERR;
+            pfds[1].revents = 0;
+
             /* 0.1s timeout, should be fine for a 'cancel' */
-            switch (qemu_poll_ns(pfds, 1, 100 * 1000 * 1000)) {
+            switch (qemu_poll_ns(pfds, 2, 100 * 1000 * 1000)) {
+            case 2:
             case 1: /* fd active */
-                return 0;
+                if (pfds[0].revents) {
+                    return 0;
+                }
+
+                if (pfds[1].revents) {
+                    ret = rdma_get_cm_event(rdma->channel, &cm_event);
+                    if (!ret) {
+                        rdma_ack_cm_event(cm_event);
+                    }
+
+                    error_report("receive cm event while wait comp channel,"
+                                 "cm event is %d", cm_event->event);
+                    if (cm_event->event == RDMA_CM_EVENT_DISCONNECTED ||
+                        cm_event->event == RDMA_CM_EVENT_DEVICE_REMOVAL) {
+                        return -EPIPE;
+                    }
+                }
+                break;
 
             case 0: /* Timeout, go around again */
                 break;