Commit 9c98cfbe authored by Dr. David Alan Gilbert's avatar Dr. David Alan Gilbert Committed by Juan Quintela
Browse files

migration/rdma: Allow cancelling while waiting for wrid 



When waiting for a WRID, if the other side dies we end up waiting
for ever with no way to cancel the migration.
Cure this by poll()ing the fd first with a timeout and checking
error flags and migration state.

Signed-off-by: default avatarDr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: default avatarPeter Xu <peterx@redhat.com>
Message-Id: <20170717110936.23314-5-dgilbert@redhat.com>
Signed-off-by: default avatarJuan Quintela <quintela@redhat.com>
parent 0b3c15f0

migration/rdma.c

+53 −6
Original line number Diff line number Diff line
@@ -1466,6 +1466,56 @@ static uint64_t qemu_rdma_poll(RDMAContext *rdma, uint64_t *wr_id_out, 
    return  0;

}



/* Wait for activity on the completion channel.

 * Returns 0 on success, none-0 on error.

 */

static int qemu_rdma_wait_comp_channel(RDMAContext *rdma)

{

    /*

     * Coroutine doesn't start until migration_fd_process_incoming()

     * so don't yield unless we know we're running inside of a coroutine.

     */

    if (rdma->migration_started_on_destination) {

        yield_until_fd_readable(rdma->comp_channel->fd);

    } else {

        /* This is the source side, we're in a separate thread

         * or destination prior to migration_fd_process_incoming()

         * we can't yield; so we have to poll the fd.

         * But we need to be able to handle 'cancel' or an error

         * without hanging forever.

         */

        while (!rdma->error_state  && !rdma->received_error) {

            GPollFD pfds[1];

            pfds[0].fd = rdma->comp_channel->fd;

            pfds[0].events = G_IO_IN | G_IO_HUP | G_IO_ERR;

            /* 0.1s timeout, should be fine for a 'cancel' */

            switch (qemu_poll_ns(pfds, 1, 100 * 1000 * 1000)) {

            case 1: /* fd active */

                return 0;



            case 0: /* Timeout, go around again */

                break;



            default: /* Error of some type -

                      * I don't trust errno from qemu_poll_ns

                     */

                error_report("%s: poll failed", __func__);

                return -EPIPE;

            }



            if (migrate_get_current()->state == MIGRATION_STATUS_CANCELLING) {

                /* Bail out and let the cancellation happen */

                return -EPIPE;

            }

        }

    }



    if (rdma->received_error) {

        return -EPIPE;

    }

    return rdma->error_state;

}



/*

 * Block until the next work request has completed.

 *
@@ -1513,12 +1563,9 @@ static int qemu_rdma_block_for_wrid(RDMAContext *rdma, int wrid_requested, 
    }



    while (1) {

        /*

         * Coroutine doesn't start until migration_fd_process_incoming()

         * so don't yield unless we know we're running inside of a coroutine.

         */

        if (rdma->migration_started_on_destination) {

            yield_until_fd_readable(rdma->comp_channel->fd);

        ret = qemu_rdma_wait_comp_channel(rdma);

        if (ret) {

            goto err_block_for_wrid;

        }



        ret = ibv_get_cq_event(rdma->comp_channel, &cq, &cq_ctx);