Commit 4bcad76f authored by Dima Stepanov's avatar Dima Stepanov Committed by Michael S. Tsirkin
Browse files

vhost-user-blk: delay vhost_user_blk_disconnect 



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 e7c83a88
  "vhost-user: delay vhost_user_stop"

Signed-off-by: default avatarDima Stepanov <dimastep@yandex-team.ru>
Message-Id: <69b73b94dcd066065595266c852810e0863a0895.1590396396.git.dimastep@yandex-team.ru>
Reviewed-by: default avatarMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: default avatarMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: default avatarLi Feng <fengli@smartx.com>
Reviewed-by: default avatarRaphael Norwitz <raphael.norwitz@nutanix.com>
parent 27109447

hw/block/vhost-user-blk.c

+37 −1
Original line number Diff line number Diff line
@@ -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: