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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: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Message-Id: <20170717110936.23314-5-dgilbert@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
This commit is contained in:
Dr. David Alan Gilbert 2017-07-17 12:09:34 +01:00 committed by Juan Quintela
parent 0b3c15f097
commit 9c98cfbe72
1 changed files with 53 additions and 6 deletions
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59
migration/rdma.c
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@ -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);