Re: [RFC spice-vdagent 02/18] vport: add by_user param to vdagent_virtio_port_disconnect_callback

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Hi,

Took me a while to get the rationale behind this so some more
info in the commit log might help.

On Tue, Aug 14, 2018 at 08:53:36PM +0200, Jakub Janků wrote:
> If the virtio port is destroyed explicitly by calling
> vdagent_virtio_port_destroy(), by_user is set to TRUE,
> otherwise to FALSE.

One issue I had was around the 'by_user' name and its meaning.
Basically, if we want to virtio_port_destroy() without any
runtime failure, by_user would be True.

I think a GError* err would fit better, as if err != NULL we
could show err->message and retry if possible. It is also true
that, under a runtime failure, most of the times before
virtio_port_destroy() is called there is a syslog(LOG_ERR, ...)
so I think GError or even a const gchar *err_msg; would be better
fit but I might be missing something.

> This will be used later with GMainLoop.

Another line about how this is related to GMainLoop might help
out while reading the patch ;)
> ---
>  src/vdagentd/virtio-port.c | 24 +++++++++++++++---------
>  src/vdagentd/virtio-port.h | 10 +++++-----
>  2 files changed, 20 insertions(+), 14 deletions(-)
> 
> diff --git a/src/vdagentd/virtio-port.c b/src/vdagentd/virtio-port.c
> index 3dc6f44..642c848 100644
> --- a/src/vdagentd/virtio-port.c
> +++ b/src/vdagentd/virtio-port.c
> @@ -122,7 +122,8 @@ error:
>      return NULL;
>  }
>  
> -void vdagent_virtio_port_destroy(struct vdagent_virtio_port **vportp)
> +static void virtio_port_destroy(struct vdagent_virtio_port **vportp,
> +                                gboolean by_user)
>  {
>      struct vdagent_virtio_port_buf *wbuf, *next_wbuf;
>      struct vdagent_virtio_port *vport = *vportp;
> @@ -132,7 +133,7 @@ void vdagent_virtio_port_destroy(struct vdagent_virtio_port **vportp)
>          return;
>  
>      if (vport->disconnect_callback)
> -        vport->disconnect_callback(vport);
> +        vport->disconnect_callback(vport, by_user);
>  
>      wbuf = vport->write_buf;
>      while (wbuf) {
> @@ -151,6 +152,11 @@ void vdagent_virtio_port_destroy(struct vdagent_virtio_port **vportp)
>      *vportp = NULL;
>  }
>  
> +void vdagent_virtio_port_destroy(struct vdagent_virtio_port **vportp)
> +{
> +    virtio_port_destroy(vportp, TRUE);
> +}
> +
>  int vdagent_virtio_port_fill_fds(struct vdagent_virtio_port *vport,
>          fd_set *readfds, fd_set *writefds)
>  {
> @@ -321,7 +327,7 @@ static void vdagent_virtio_port_do_chunk(struct vdagent_virtio_port **vportp)
>                  port->message_data = malloc(port->message_header.size);
>                  if (!port->message_data) {
>                      syslog(LOG_ERR, "out of memory, disconnecting virtio");
> -                    vdagent_virtio_port_destroy(vportp);
> +                    virtio_port_destroy(vportp, FALSE);
>                      return;
>                  }
>              }
> @@ -335,7 +341,7 @@ static void vdagent_virtio_port_do_chunk(struct vdagent_virtio_port **vportp)
>  
>          if (avail > read) {
>              syslog(LOG_ERR, "chunk larger than message, lost sync?");
> -            vdagent_virtio_port_destroy(vportp);
> +            virtio_port_destroy(vportp, FALSE);
>              return;
>          }
>  
> @@ -353,7 +359,7 @@ static void vdagent_virtio_port_do_chunk(struct vdagent_virtio_port **vportp)
>                  int r = vport->read_callback(vport, vport->chunk_header.port,
>                                   &port->message_header, port->message_data);
>                  if (r == -1) {
> -                    vdagent_virtio_port_destroy(vportp);
> +                    virtio_port_destroy(vportp, TRUE);

I wonder if this can't be an actual failure too? (i.e by_user =
FALSE)

Reviewed-by: Victor Toso <victortoso@xxxxxxxxxx>

Cheers,
Victor
>                      return;
>                  }
>              }
> @@ -420,7 +426,7 @@ static void vdagent_virtio_port_do_read(struct vdagent_virtio_port **vportp)
>          return;
>      }
>      if (n <= 0) {
> -        vdagent_virtio_port_destroy(vportp);
> +        virtio_port_destroy(vportp, FALSE);
>          return;
>      }
>      vport->opening = 0;
> @@ -433,13 +439,13 @@ static void vdagent_virtio_port_do_read(struct vdagent_virtio_port **vportp)
>              if (vport->chunk_header.size > VD_AGENT_MAX_DATA_SIZE) {
>                  syslog(LOG_ERR, "chunk size %u too large",
>                         vport->chunk_header.size);
> -                vdagent_virtio_port_destroy(vportp);
> +                virtio_port_destroy(vportp, FALSE);
>                  return;
>              }
>              if (vport->chunk_header.port >= VDP_END_PORT) {
>                  syslog(LOG_ERR, "chunk port %u out of range",
>                         vport->chunk_header.port);
> -                vdagent_virtio_port_destroy(vportp);
> +                virtio_port_destroy(vportp, FALSE);
>                  return;
>              }
>          }
> @@ -487,7 +493,7 @@ static void vdagent_virtio_port_do_write(struct vdagent_virtio_port **vportp)
>          if (errno == EINTR)
>              return;
>          syslog(LOG_ERR, "writing to vdagent virtio port: %m");
> -        vdagent_virtio_port_destroy(vportp);
> +        virtio_port_destroy(vportp, FALSE);
>          return;
>      }
>      if (n > 0)
> diff --git a/src/vdagentd/virtio-port.h b/src/vdagentd/virtio-port.h
> index f899e30..3c701d6 100644
> --- a/src/vdagentd/virtio-port.h
> +++ b/src/vdagentd/virtio-port.h
> @@ -41,14 +41,14 @@ typedef int (*vdagent_virtio_port_read_callback)(
>      uint8_t *data);
>  
>  /* Callbacks with this type will be called when the port is disconnected.
> +   If the disconnect is initiated by calling vdagent_virtio_port_destroy()
> +   or by returning -1 from the vdagent_virtio_port_read_callback,
> +   @by_user is set to TRUE, otherwise FALSE.
>     Note:
>     1) vdagent_virtio_port will destroy the port in question itself after
> -      this callback has completed!
> -   2) This callback is always called, even if the disconnect is initiated
> -      by the vdagent_virtio_port user through returning -1 from a read
> -      callback, or by explicitly calling vdagent_virtio_port_destroy */
> +      this callback has completed! */
>  typedef void (*vdagent_virtio_port_disconnect_callback)(
> -    struct vdagent_virtio_port *conn);
> +    struct vdagent_virtio_port *conn, gboolean by_user);
>  
>  
>  /* Create a vdagent virtio port object for port portname */
> -- 
> 2.17.1
> 
> _______________________________________________
> Spice-devel mailing list
> Spice-devel@xxxxxxxxxxxxxxxxxxxxx
> https://lists.freedesktop.org/mailman/listinfo/spice-devel

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