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vhost-user: fix lost reconnect

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When the vhost-user is reconnecting to the backend, and if the vhost-user fails
at the get_features in vhost_dev_init(), then the reconnect will fail
and it will not be retriggered forever.

The reason is:
When the vhost-user fails at get_features, the vhost_dev_cleanup will be called
immediately.

vhost_dev_cleanup calls 'memset(hdev, 0, sizeof(struct vhost_dev))'.

The reconnect path is:
vhost_user_blk_event
   vhost_user_async_close(.. vhost_user_blk_disconnect ..)
     qemu_chr_fe_set_handlers <----- clear the notifier callback
       schedule vhost_user_async_close_bh

The vhost->vdev is null, so the vhost_user_blk_disconnect will not be
called, then the event fd callback will not be reinstalled.

All vhost-user devices have this issue, including vhost-user-blk/scsi.

With this patch, if the vdev->vdev is null, the fd callback will still
be reinstalled.

Fixes: 71e076a07d ("hw/virtio: generalise CHR_EVENT_CLOSED handling")

Signed-off-by: Li Feng <fengli@smartx.com>
Reviewed-by: Raphael Norwitz <raphael.norwitz@nutanix.com>
Message-Id: <20231009044735.941655-6-fengli@smartx.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
This commit is contained in:
Li Feng 2023-10-09 12:47:01 +08:00 • committed by Michael S. Tsirkin
parent a6a30a7ec0
commit f02a4b8e64
5 changed files with 14 additions and 6 deletions
Download patch file Download diff file Expand all files Collapse all files

2
hw/virtio/vhost-user-gpio.c
View file

@ -289,7 +289,7 @@ static void vu_gpio_event(void *opaque, QEMUChrEvent event)
case CHR_EVENT_CLOSED:
/* defer close until later to avoid circular close */
vhost_user_async_close(dev, &gpio->chardev, &gpio->vhost_dev,
vu_gpio_disconnect);
vu_gpio_disconnect, vu_gpio_event);
break;
case CHR_EVENT_BREAK:
case CHR_EVENT_MUX_IN: