diff mbox series

[v4,2/2] vhost-user: fix lost reconnect again

Message ID 20240516025753.130171-3-fengli@smartx.com
State New
Headers show
Series [v4,1/2] Revert "vhost-user: fix lost reconnect" | expand

Commit Message

Li Feng May 16, 2024, 2:57 a.m. UTC
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 fail 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.

We need to ensure that even if vhost_dev_init initialization fails, the event
handler still needs to be reinstalled when s->connected is false.

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

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

Signed-off-by: Li Feng <fengli@smartx.com>
---
 hw/block/vhost-user-blk.c   |  3 ++-
 hw/scsi/vhost-user-scsi.c   |  3 ++-
 hw/virtio/vhost-user-base.c |  3 ++-
 hw/virtio/vhost-user.c      | 10 +---------
 4 files changed, 7 insertions(+), 12 deletions(-)

Comments

Raphael Norwitz May 16, 2024, 4:20 a.m. UTC | #1
On Wed, May 15, 2024 at 10:58 PM Li Feng <fengli@smartx.com> wrote:
>
> 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 fail 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.
>
> We need to ensure that even if vhost_dev_init initialization fails, the event
> handler still needs to be reinstalled when s->connected is false.
>
> All vhost-user devices have this issue, including vhost-user-blk/scsi.
>
> Fixes: 71e076a07d ("hw/virtio: generalise CHR_EVENT_CLOSED handling")
>

Reviewed-by: Raphael Norwitz <raphael@enfabrica.net>

> Signed-off-by: Li Feng <fengli@smartx.com>
> ---
>  hw/block/vhost-user-blk.c   |  3 ++-
>  hw/scsi/vhost-user-scsi.c   |  3 ++-
>  hw/virtio/vhost-user-base.c |  3 ++-
>  hw/virtio/vhost-user.c      | 10 +---------
>  4 files changed, 7 insertions(+), 12 deletions(-)
>
> diff --git a/hw/block/vhost-user-blk.c b/hw/block/vhost-user-blk.c
> index 41d1ac3a5a..c6842ced48 100644
> --- a/hw/block/vhost-user-blk.c
> +++ b/hw/block/vhost-user-blk.c
> @@ -353,7 +353,7 @@ static void vhost_user_blk_disconnect(DeviceState *dev)
>      VHostUserBlk *s = VHOST_USER_BLK(vdev);
>
>      if (!s->connected) {
> -        return;
> +        goto done;
>      }
>      s->connected = false;
>
> @@ -361,6 +361,7 @@ static void vhost_user_blk_disconnect(DeviceState *dev)
>
>      vhost_dev_cleanup(&s->dev);
>
> +done:
>      /* Re-instate the event handler for new connections */
>      qemu_chr_fe_set_handlers(&s->chardev, NULL, NULL, vhost_user_blk_event,
>                               NULL, dev, NULL, true);
> diff --git a/hw/scsi/vhost-user-scsi.c b/hw/scsi/vhost-user-scsi.c
> index 48a59e020e..b49a11d23b 100644
> --- a/hw/scsi/vhost-user-scsi.c
> +++ b/hw/scsi/vhost-user-scsi.c
> @@ -181,7 +181,7 @@ static void vhost_user_scsi_disconnect(DeviceState *dev)
>      VirtIOSCSICommon *vs = VIRTIO_SCSI_COMMON(dev);
>
>      if (!s->connected) {
> -        return;
> +        goto done;
>      }
>      s->connected = false;
>
> @@ -189,6 +189,7 @@ static void vhost_user_scsi_disconnect(DeviceState *dev)
>
>      vhost_dev_cleanup(&vsc->dev);
>
> +done:
>      /* Re-instate the event handler for new connections */
>      qemu_chr_fe_set_handlers(&vs->conf.chardev, NULL, NULL,
>                               vhost_user_scsi_event, NULL, dev, NULL, true);
> diff --git a/hw/virtio/vhost-user-base.c b/hw/virtio/vhost-user-base.c
> index 4b54255682..11e72b1e3b 100644
> --- a/hw/virtio/vhost-user-base.c
> +++ b/hw/virtio/vhost-user-base.c
> @@ -225,13 +225,14 @@ static void vub_disconnect(DeviceState *dev)
>      VHostUserBase *vub = VHOST_USER_BASE(vdev);
>
>      if (!vub->connected) {
> -        return;
> +        goto done;
>      }
>      vub->connected = false;
>
>      vub_stop(vdev);
>      vhost_dev_cleanup(&vub->vhost_dev);
>
> +done:
>      /* Re-instate the event handler for new connections */
>      qemu_chr_fe_set_handlers(&vub->chardev,
>                               NULL, NULL, vub_event,
> diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c
> index c929097e87..c407ea8939 100644
> --- a/hw/virtio/vhost-user.c
> +++ b/hw/virtio/vhost-user.c
> @@ -2781,16 +2781,8 @@ typedef struct {
>  static void vhost_user_async_close_bh(void *opaque)
>  {
>      VhostAsyncCallback *data = opaque;
> -    struct vhost_dev *vhost = data->vhost;
>
> -    /*
> -     * If the vhost_dev has been cleared in the meantime there is
> -     * nothing left to do as some other path has completed the
> -     * cleanup.
> -     */
> -    if (vhost->vdev) {
> -        data->cb(data->dev);
> -    }
> +    data->cb(data->dev);
>
>      g_free(data);
>  }
> --
> 2.45.0
>
diff mbox series

Patch

diff --git a/hw/block/vhost-user-blk.c b/hw/block/vhost-user-blk.c
index 41d1ac3a5a..c6842ced48 100644
--- a/hw/block/vhost-user-blk.c
+++ b/hw/block/vhost-user-blk.c
@@ -353,7 +353,7 @@  static void vhost_user_blk_disconnect(DeviceState *dev)
     VHostUserBlk *s = VHOST_USER_BLK(vdev);
 
     if (!s->connected) {
-        return;
+        goto done;
     }
     s->connected = false;
 
@@ -361,6 +361,7 @@  static void vhost_user_blk_disconnect(DeviceState *dev)
 
     vhost_dev_cleanup(&s->dev);
 
+done:
     /* Re-instate the event handler for new connections */
     qemu_chr_fe_set_handlers(&s->chardev, NULL, NULL, vhost_user_blk_event,
                              NULL, dev, NULL, true);
diff --git a/hw/scsi/vhost-user-scsi.c b/hw/scsi/vhost-user-scsi.c
index 48a59e020e..b49a11d23b 100644
--- a/hw/scsi/vhost-user-scsi.c
+++ b/hw/scsi/vhost-user-scsi.c
@@ -181,7 +181,7 @@  static void vhost_user_scsi_disconnect(DeviceState *dev)
     VirtIOSCSICommon *vs = VIRTIO_SCSI_COMMON(dev);
 
     if (!s->connected) {
-        return;
+        goto done;
     }
     s->connected = false;
 
@@ -189,6 +189,7 @@  static void vhost_user_scsi_disconnect(DeviceState *dev)
 
     vhost_dev_cleanup(&vsc->dev);
 
+done:
     /* Re-instate the event handler for new connections */
     qemu_chr_fe_set_handlers(&vs->conf.chardev, NULL, NULL,
                              vhost_user_scsi_event, NULL, dev, NULL, true);
diff --git a/hw/virtio/vhost-user-base.c b/hw/virtio/vhost-user-base.c
index 4b54255682..11e72b1e3b 100644
--- a/hw/virtio/vhost-user-base.c
+++ b/hw/virtio/vhost-user-base.c
@@ -225,13 +225,14 @@  static void vub_disconnect(DeviceState *dev)
     VHostUserBase *vub = VHOST_USER_BASE(vdev);
 
     if (!vub->connected) {
-        return;
+        goto done;
     }
     vub->connected = false;
 
     vub_stop(vdev);
     vhost_dev_cleanup(&vub->vhost_dev);
 
+done:
     /* Re-instate the event handler for new connections */
     qemu_chr_fe_set_handlers(&vub->chardev,
                              NULL, NULL, vub_event,
diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c
index c929097e87..c407ea8939 100644
--- a/hw/virtio/vhost-user.c
+++ b/hw/virtio/vhost-user.c
@@ -2781,16 +2781,8 @@  typedef struct {
 static void vhost_user_async_close_bh(void *opaque)
 {
     VhostAsyncCallback *data = opaque;
-    struct vhost_dev *vhost = data->vhost;
 
-    /*
-     * If the vhost_dev has been cleared in the meantime there is
-     * nothing left to do as some other path has completed the
-     * cleanup.
-     */
-    if (vhost->vdev) {
-        data->cb(data->dev);
-    }
+    data->cb(data->dev);
 
     g_free(data);
 }