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call HotplugHandler->plug() as the last step in device realization

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When [2] was fixed it was agreed that adding and calling post_plug()
callback after device_reset() was low risk approach to hotfix issue
right before release. So it was merged instead of moving already
existing plug() callback after device_reset() is called which would
be more risky and require all plug() callbacks audit.

Looking at the current plug() callbacks, it doesn't seem that moving
plug() callback after device_reset() is breaking anything, so here
goes agreed upon [3] proper fix which essentially reverts [1][2]
and moves plug() callback after device_reset().
This way devices always comes to plug() stage, after it's been fully
initialized (including being reset), which fixes race condition [2]
without need for an extra post_plug() callback.

 1. (25e897881 "qdev: add HotplugHandler->post_plug() callback")
 2. (8449bcf94 "virtio-scsi: fix hotplug ->reset() vs event race")
 3. https://www.mail-archive.com/qemu-devel@nongnu.org/msg549915.html

Signed-off-by: Igor Mammedov <imammedo@redhat.com>
Message-Id: <1539696820-273275-1-git-send-email-imammedo@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Tested-by: Pierre Morel<pmorel@linux.ibm.com>
Acked-by: Pierre Morel<pmorel@linux.ibm.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Igor Mammedov 2018-10-16 15:33:40 +02:00 • committed by Paolo Bonzini
parent ac0989f53d
commit 8b5e6caf01
4 changed files with 7 additions and 41 deletions
Download patch file Download diff file Expand all files Collapse all files

11
hw/scsi/virtio-scsi.c
View file

@ -797,16 +797,8 @@ static void virtio_scsi_hotplug(HotplugHandler *hotplug_dev, DeviceState *dev,
virtio_scsi_acquire(s);
blk_set_aio_context(sd->conf.blk, s->ctx);
virtio_scsi_release(s);
}
}
/* Announce the new device after it has been plugged */
static void virtio_scsi_post_hotplug(HotplugHandler *hotplug_dev,
DeviceState *dev)
{
VirtIODevice *vdev = VIRTIO_DEVICE(hotplug_dev);
VirtIOSCSI *s = VIRTIO_SCSI(vdev);
SCSIDevice *sd = SCSI_DEVICE(dev);
}
if (virtio_vdev_has_feature(vdev, VIRTIO_SCSI_F_HOTPLUG)) {
virtio_scsi_acquire(s);
@ -976,7 +968,6 @@ static void virtio_scsi_class_init(ObjectClass *klass, void *data)
vdc->start_ioeventfd = virtio_scsi_dataplane_start;
vdc->stop_ioeventfd = virtio_scsi_dataplane_stop;
hc->plug = virtio_scsi_hotplug;
hc->post_plug = virtio_scsi_post_hotplug;
hc->unplug = virtio_scsi_hotunplug;
}