From 9cf2bab2edca1e651eef49f2417f8f67bdfe49bb Mon Sep 17 00:00:00 2001 From: "Dr. David Alan Gilbert" Date: Mon, 17 Jul 2017 12:09:31 +0100 Subject: [PATCH] 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: Dr. David Alan Gilbert Reviewed-by: Peter Xu Message-Id: <20170717110936.23314-2-dgilbert@redhat.com> Signed-off-by: Juan Quintela --- migration/rdma.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) diff --git a/migration/rdma.c b/migration/rdma.c index c6bc607a03..6111e10c70 100644 --- a/migration/rdma.c +++ b/migration/rdma.c @@ -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;