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vhost-user-blk: delay vhost_user_blk_disconnect

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A socket write during vhost-user communication may trigger a disconnect
event, calling vhost_user_blk_disconnect() and clearing all the
vhost_dev structures holding data that vhost-user functions expect to
remain valid to roll back initialization correctly. Delay the cleanup to
keep vhost_dev structure valid.
There are two possible states to handle:
1. RUN_STATE_PRELAUNCH: skip bh oneshot call and perform disconnect in
the caller routine.
2. RUN_STATE_RUNNING: delay by using bh

BH changes are based on the similar changes for the vhost-user-net
device:
  commit e7c83a885f
  "vhost-user: delay vhost_user_stop"

Signed-off-by: Dima Stepanov <dimastep@yandex-team.ru>
Message-Id: <69b73b94dcd066065595266c852810e0863a0895.1590396396.git.dimastep@yandex-team.ru>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Li Feng <fengli@smartx.com>
Reviewed-by: Raphael Norwitz <raphael.norwitz@nutanix.com>
This commit is contained in:
Dima Stepanov 2020-05-28 12:11:19 +03:00 committed by Michael S. Tsirkin
parent 271094474b
commit 4bcad76f4c
1 changed files with 37 additions and 1 deletions
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38
hw/block/vhost-user-blk.c
View File

@ -349,6 +349,19 @@ static void vhost_user_blk_disconnect(DeviceState *dev)
vhost_dev_cleanup(&s->dev);
}
static void vhost_user_blk_event(void *opaque, QEMUChrEvent event);
static void vhost_user_blk_chr_closed_bh(void *opaque)
{
DeviceState *dev = opaque;
VirtIODevice *vdev = VIRTIO_DEVICE(dev);
VHostUserBlk *s = VHOST_USER_BLK(vdev);
vhost_user_blk_disconnect(dev);
qemu_chr_fe_set_handlers(&s->chardev, NULL, NULL, vhost_user_blk_event,
NULL, opaque, NULL, true);
}
static void vhost_user_blk_event(void *opaque, QEMUChrEvent event)
{
DeviceState *dev = opaque;
@ -363,7 +376,30 @@ static void vhost_user_blk_event(void *opaque, QEMUChrEvent event)
}
break;
case CHR_EVENT_CLOSED:
vhost_user_blk_disconnect(dev);
/*
* A close event may happen during a read/write, but vhost
* code assumes the vhost_dev remains setup, so delay the
* stop & clear. There are two possible paths to hit this
* disconnect event:
* 1. When VM is in the RUN_STATE_PRELAUNCH state. The
* vhost_user_blk_device_realize() is a caller.
* 2. In tha main loop phase after VM start.
*
* For p2 the disconnect event will be delayed. We can't
* do the same for p1, because we are not running the loop
* at this moment. So just skip this step and perform
* disconnect in the caller function.
*
* TODO: maybe it is a good idea to make the same fix
* for other vhost-user devices.
*/
if (runstate_is_running()) {
AioContext *ctx = qemu_get_current_aio_context();
qemu_chr_fe_set_handlers(&s->chardev, NULL, NULL, NULL, NULL,
NULL, NULL, false);
aio_bh_schedule_oneshot(ctx, vhost_user_blk_chr_closed_bh, opaque);
}
break;
case CHR_EVENT_BREAK:
case CHR_EVENT_MUX_IN: