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dataplane: fix hang introduced by AioContext transition

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The bug is that the EventNotifiers do have a NULL io_flush callback.
Because _none_ of the callbacks on the dataplane AioContext have such a
callback, aio_poll will simply do nothing.  Fixed by adding the callbacks:
the ioeventfd will always be polled (this can change in the future to
pause/resume the processing during live snapshots or similar operations);
the ioqueue will be polled if there are outstanding requests.

I must admit I have screwed up my testing somehow, because commit
2c20e71 does not work even if cherry-picked on top of 1.4.0, and this
patch fixes it there as well.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
This commit is contained in:
Paolo Bonzini 2013-03-13 15:14:15 +01:00 committed by Stefan Hajnoczi
parent 28f0824696
commit 485e3ce88e
1 changed files with 15 additions and 2 deletions
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17
hw/dataplane/virtio-blk.c
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@ -263,6 +263,11 @@ static int process_request(IOQueue *ioq, struct iovec iov[],
}
}
static int flush_true(EventNotifier *e)
{
return true;
}
static void handle_notify(EventNotifier *e)
{
VirtIOBlockDataPlane *s = container_of(e, VirtIOBlockDataPlane,
@ -342,6 +347,14 @@ static void handle_notify(EventNotifier *e)
}
}
static int flush_io(EventNotifier *e)
{
VirtIOBlockDataPlane *s = container_of(e, VirtIOBlockDataPlane,
io_notifier);
return s->num_reqs > 0;
}
static void handle_io(EventNotifier *e)
{
VirtIOBlockDataPlane *s = container_of(e, VirtIOBlockDataPlane,
@ -472,7 +485,7 @@ void virtio_blk_data_plane_start(VirtIOBlockDataPlane *s)
exit(1);
}
s->host_notifier = *virtio_queue_get_host_notifier(vq);
aio_set_event_notifier(s->ctx, &s->host_notifier, handle_notify, NULL);
aio_set_event_notifier(s->ctx, &s->host_notifier, handle_notify, flush_true);
/* Set up ioqueue */
ioq_init(&s->ioqueue, s->fd, REQ_MAX);
@ -480,7 +493,7 @@ void virtio_blk_data_plane_start(VirtIOBlockDataPlane *s)
ioq_put_iocb(&s->ioqueue, &s->requests[i].iocb);
}
s->io_notifier = *ioq_get_notifier(&s->ioqueue);
aio_set_event_notifier(s->ctx, &s->io_notifier, handle_io, NULL);
aio_set_event_notifier(s->ctx, &s->io_notifier, handle_io, flush_io);
s->started = true;
trace_virtio_blk_data_plane_start(s);