Commit 9cf2bab2 authored by Dr. David Alan Gilbert's avatar Dr. David Alan Gilbert Committed by Juan Quintela
Browse files

migration/rdma: Fix race on source 

Fix a race where the destination might try and send the source a
WRID_READY before the source has done a post-recv for it.

rdma_post_recv has to happen after the qp exists, and we're
OK since we've already called qemu_rdma_source_init that calls
qemu_alloc_qp.

This corresponds to:
https://bugzilla.redhat.com/show_bug.cgi?id=1285044



The race can be triggered by adding a few ms wait before this
post_recv_control (which was originally due to me turning on loads of
debug).

Signed-off-by: default avatarDr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: default avatarPeter Xu <peterx@redhat.com>
Message-Id: <20170717110936.23314-2-dgilbert@redhat.com>
Signed-off-by: default avatarJuan Quintela <quintela@redhat.com>
parent e9277a19

migration/rdma.c

+6 −6
Original line number Diff line number Diff line
@@ -2365,6 +2365,12 @@ static int qemu_rdma_connect(RDMAContext *rdma, Error **errp) 


    caps_to_network(&cap);



    ret = qemu_rdma_post_recv_control(rdma, RDMA_WRID_READY);

    if (ret) {

        ERROR(errp, "posting second control recv");

        goto err_rdma_source_connect;

    }



    ret = rdma_connect(rdma->cm_id, &conn_param);

    if (ret) {

        perror("rdma_connect");
@@ -2405,12 +2411,6 @@ static int qemu_rdma_connect(RDMAContext *rdma, Error **errp) 


    rdma_ack_cm_event(cm_event);



    ret = qemu_rdma_post_recv_control(rdma, RDMA_WRID_READY);

    if (ret) {

        ERROR(errp, "posting second control recv!");

        goto err_rdma_source_connect;

    }



    rdma->control_ready_expected = 1;

    rdma->nb_sent = 0;

    return 0;