diff options
| -rw-r--r-- | hw/block/dataplane/virtio-blk.c | 53 |
1 files changed, 31 insertions, 22 deletions
diff --git a/hw/block/dataplane/virtio-blk.c b/hw/block/dataplane/virtio-blk.c index c227b39..da36fcf 100644 --- a/hw/block/dataplane/virtio-blk.c +++ b/hw/block/dataplane/virtio-blk.c @@ -219,13 +219,6 @@ int virtio_blk_data_plane_start(VirtIODevice *vdev) memory_region_transaction_commit(); - /* - * These fields are visible to the IOThread so we rely on implicit barriers - * in aio_context_acquire() on the write side and aio_notify_accept() on - * the read side. - */ - s->starting = false; - vblk->dataplane_started = true; trace_virtio_blk_data_plane_start(s); old_context = blk_get_aio_context(s->conf->conf.blk); @@ -244,6 +237,18 @@ int virtio_blk_data_plane_start(VirtIODevice *vdev) event_notifier_set(virtio_queue_get_host_notifier(vq)); } + /* + * These fields must be visible to the IOThread when it processes the + * virtqueue, otherwise it will think dataplane has not started yet. + * + * Make sure ->dataplane_started is false when blk_set_aio_context() is + * called above so that draining does not cause the host notifier to be + * detached/attached prematurely. + */ + s->starting = false; + vblk->dataplane_started = true; + smp_wmb(); /* paired with aio_notify_accept() on the read side */ + /* Get this show started by hooking up our callbacks */ if (!blk_in_drain(s->conf->conf.blk)) { aio_context_acquire(s->ctx); @@ -273,7 +278,6 @@ int virtio_blk_data_plane_start(VirtIODevice *vdev) fail_guest_notifiers: vblk->dataplane_disabled = true; s->starting = false; - vblk->dataplane_started = true; return -ENOSYS; } @@ -327,19 +331,6 @@ void virtio_blk_data_plane_stop(VirtIODevice *vdev) aio_wait_bh_oneshot(s->ctx, virtio_blk_data_plane_stop_bh, s); } - aio_context_acquire(s->ctx); - - /* Wait for virtio_blk_dma_restart_bh() and in flight I/O to complete */ - blk_drain(s->conf->conf.blk); - - /* - * Try to switch bs back to the QEMU main loop. If other users keep the - * BlockBackend in the iothread, that's ok - */ - blk_set_aio_context(s->conf->conf.blk, qemu_get_aio_context(), NULL); - - aio_context_release(s->ctx); - /* * Batch all the host notifiers in a single transaction to avoid * quadratic time complexity in address_space_update_ioeventfds(). @@ -360,12 +351,30 @@ void virtio_blk_data_plane_stop(VirtIODevice *vdev) virtio_bus_cleanup_host_notifier(VIRTIO_BUS(qbus), i); } + /* + * Set ->dataplane_started to false before draining so that host notifiers + * are not detached/attached anymore. + */ + vblk->dataplane_started = false; + + aio_context_acquire(s->ctx); + + /* Wait for virtio_blk_dma_restart_bh() and in flight I/O to complete */ + blk_drain(s->conf->conf.blk); + + /* + * Try to switch bs back to the QEMU main loop. If other users keep the + * BlockBackend in the iothread, that's ok + */ + blk_set_aio_context(s->conf->conf.blk, qemu_get_aio_context(), NULL); + + aio_context_release(s->ctx); + qemu_bh_cancel(s->bh); notify_guest_bh(s); /* final chance to notify guest */ /* Clean up guest notifier (irq) */ k->set_guest_notifiers(qbus->parent, nvqs, false); - vblk->dataplane_started = false; s->stopping = false; } |