This series looks at the other side of the broken "qmp transaction" problem with dataplane [1] - the event loop.
Before, an ioeventfd of a non-dataplane device is registered via qemu_set_fd_handler, which is only polled directly by main_loop_wait(), not in aio_poll(); an ioeventfd of a dataplane device (virtio-blk/virtio-scsi) is registered specially via aio_set_event_notifier, which is a wrapper of aio_set_fd_handler, thus it WILL be polled by all aio_poll(). As explained in [1], and in patch 3, this is wrong. The handlers mustn't run. [1] Fixes it by unregistering them temporarily around such nested poll, while this series fixes it by skipping those file descriptors in all nested aio_poll(), just like how iohandler behaves in the main loop. On the one hand, it is simpler than [1]; on the other hand, this approach is also interesting because once we remove qemu_set_fd_handler2 [2], iohandler.c can be removed by converting all qemu_set_fd_handler to the new aio_set_io_event_notifier introduced in this series. Note that patch 2 is not tested. [1]: https://lists.gnu.org/archive/html/qemu-block/2015-05/msg00800.html [2]: https://lists.gnu.org/archive/html/qemu-block/2015-05/msg00647.html Fam Zheng (4): aio-posix: Introduce aio_set_io_event_notifier aio-win32: Implement aio_set_io_event_notifier virtio-blk: Use aio_set_io_event_notifier in dataplane virtio-scsi-dataplane: User aio_set_io_event_notifier aio-posix.c | 33 +++++++++++++++++++----- aio-win32.c | 56 ++++++++++++++++++++++++++++++++++------- hw/block/dataplane/virtio-blk.c | 4 +-- hw/scsi/virtio-scsi-dataplane.c | 18 +++++++------ include/block/aio.h | 23 ++++++++++++++--- 5 files changed, 106 insertions(+), 28 deletions(-) -- 2.4.1
