We hit following error during testing RDMA transport:
in case of migration error, mgmt daemon pick one migration port,
incoming rdma:[::]:8089: RDMA ERROR: Error: could not rdma_bind_addr

Then try another -incoming rdma:[::]:8103, sometime it worked,
sometimes need another try with other ports number.

Set the REUSEADDR option for destination, This allow address could
be reused to avoid rdma_bind_addr error out.

Signed-off-by: Jack Wang <jinpu.wang@ionos.com>
Reviewed-by: Pankaj Gupta <pankaj.gupta@ionos.com
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

---
v3: add reviewed-by tags from David and Pankaj.
v2: extend commit message as discussed with Pankaj and David
---
 migration/rdma.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/migration/rdma.c b/migration/rdma.c
index c7c7a384875b..663e1fbb096d 100644
--- a/migration/rdma.c
+++ b/migration/rdma.c
@@ -2705,6 +2705,7 @@ static int qemu_rdma_dest_init(RDMAContext *rdma, Error **errp)
     char ip[40] = "unknown";
     struct rdma_addrinfo *res, *e;
     char port_str[16];
+    int reuse = 1;
 
     for (idx = 0; idx < RDMA_WRID_MAX; idx++) {
         rdma->wr_data[idx].control_len = 0;
@@ -2740,6 +2741,12 @@ static int qemu_rdma_dest_init(RDMAContext *rdma, Error **errp)
         goto err_dest_init_bind_addr;
     }
 
+    ret = rdma_set_option(listen_id, RDMA_OPTION_ID, RDMA_OPTION_ID_REUSEADDR,
+			  &reuse, sizeof reuse);
+    if (ret) {
+        ERROR(errp, "Error: could not set REUSEADDR option");
+        goto err_dest_init_bind_addr;
+    }
     for (e = res; e != NULL; e = e->ai_next) {
         inet_ntop(e->ai_family,
             &((struct sockaddr_in *) e->ai_dst_addr)->sin_addr, ip, sizeof ip);
-- 
2.25.1