[v2,15/15] chardev: tcp: postpone TLS work until machine done

TLS handshake may create background GSource tasks, while we won't know
the correct GMainContext until the whole chardev (including frontend)
inited.  Let's postpone the initial TLS handshake until machine done.

If we dynamically add tcp chardev, it won't be affected since we have a
new tcp_chr_machine_done flag to know whether we should postpone it or
not.

Signed-off-by: Peter Xu <peterx@redhat.com>
---
 chardev/char-socket.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

On Thu, Mar 01, 2018 at 04:44:38PM +0800, Peter Xu wrote:
> TLS handshake may create background GSource tasks, while we won't know
> the correct GMainContext until the whole chardev (including frontend)
> inited.  Let's postpone the initial TLS handshake until machine done.
> 
> If we dynamically add tcp chardev, it won't be affected since we have a
> new tcp_chr_machine_done flag to know whether we should postpone it or
> not.
> 
> Signed-off-by: Peter Xu <peterx@redhat.com>
> ---
>  chardev/char-socket.c | 14 ++++++++++++++
>  1 file changed, 14 insertions(+)

I don't like this patch either for the same reasons as previous
patch - its creating different behaviour depending on whether
the 'wait' flag happens to have been set in -chardev.

> 
> diff --git a/chardev/char-socket.c b/chardev/char-socket.c
> index 2b355fc7a8..13aeca0b27 100644
> --- a/chardev/char-socket.c
> +++ b/chardev/char-socket.c
> @@ -72,6 +72,8 @@ typedef struct {
>  static gboolean socket_reconnect_timeout(gpointer opaque);
>  static void tcp_chr_telnet_init(Chardev *chr);
>  
> +static bool tcp_chr_machine_done;
> +
>  static void tcp_chr_reconn_timer_cancel(SocketChardev *s)
>  {
>      if (s->reconnect_timer) {
> @@ -719,6 +721,11 @@ static void tcp_chr_tls_init(Chardev *chr)
>      Error *err = NULL;
>      gchar *name;
>  
> +    if (!tcp_chr_machine_done) {
> +        /* This will be postponed to machine_done notifier */
> +        return;
> +    }
> +
>      if (s->is_listen) {
>          tioc = qio_channel_tls_new_server(
>              s->ioc, s->tls_creds,
> @@ -1131,10 +1138,17 @@ static int tcp_chr_machine_done_hook(Chardev *chr)
>  {
>      SocketChardev *s = SOCKET_CHARDEV(chr);
>  
> +    /* Set it multiple times won't hurt */
> +    tcp_chr_machine_done = true;
> +
>      if (s->reconnect_time) {
>          tcp_chr_connect_async(chr);
>      }
>  
> +    if (s->tls_creds) {
> +        tcp_chr_tls_init(chr);
> +    }
> +
>      return 0;
>  }
>  
> -- 
> 2.14.3
> 

Regards,
Daniel

On 01/03/2018 09:44, Peter Xu wrote:
> +static bool tcp_chr_machine_done;
> +
>  static void tcp_chr_reconn_timer_cancel(SocketChardev *s)
>  {
>      if (s->reconnect_timer) {
> @@ -719,6 +721,11 @@ static void tcp_chr_tls_init(Chardev *chr)
>      Error *err = NULL;
>      gchar *name;
>  
> +    if (!tcp_chr_machine_done) {
> +        /* This will be postponed to machine_done notifier */
> +        return;
> +    }
> +

Can you instead add a global machine_init_done bool to vl.c and
include/sysemu/sysemu.h (and make it always true in
stubs/machine-init-done.c)?

Then muxes_realized can go away too.

Thanks,

Paolo

On Thu, Mar 01, 2018 at 04:03:04PM +0000, Daniel P. Berrangé wrote:
> On Thu, Mar 01, 2018 at 04:44:38PM +0800, Peter Xu wrote:
> > TLS handshake may create background GSource tasks, while we won't know
> > the correct GMainContext until the whole chardev (including frontend)
> > inited.  Let's postpone the initial TLS handshake until machine done.
> > 
> > If we dynamically add tcp chardev, it won't be affected since we have a
> > new tcp_chr_machine_done flag to know whether we should postpone it or
> > not.
> > 
> > Signed-off-by: Peter Xu <peterx@redhat.com>
> > ---
> >  chardev/char-socket.c | 14 ++++++++++++++
> >  1 file changed, 14 insertions(+)
> 
> I don't like this patch either for the same reasons as previous
> patch - its creating different behaviour depending on whether
> the 'wait' flag happens to have been set in -chardev.

IMHO it's because the socket chardev is indeed complicated... If you
see qmp_chardev_open_socket(), that's where most of the complexity
lies in.  And as I explained, each of the patch, or group of patches,
were only trying to solve a single problem.

Though I admit this patch has brought a little bit more complexity,
though in the short term I don't see a better solution. And, if you
consider the existing MUX machine done hook, then it's merely using
the same way to do it but even cleaned it up a bit...

Please let me know if you have any suggestion that I can do it in a
better way.  Thanks!

On Thu, Mar 01, 2018 at 06:37:47PM +0100, Paolo Bonzini wrote:
> On 01/03/2018 09:44, Peter Xu wrote:
> > +static bool tcp_chr_machine_done;
> > +
> >  static void tcp_chr_reconn_timer_cancel(SocketChardev *s)
> >  {
> >      if (s->reconnect_timer) {
> > @@ -719,6 +721,11 @@ static void tcp_chr_tls_init(Chardev *chr)
> >      Error *err = NULL;
> >      gchar *name;
> >  
> > +    if (!tcp_chr_machine_done) {
> > +        /* This will be postponed to machine_done notifier */
> > +        return;
> > +    }
> > +
> 
> Can you instead add a global machine_init_done bool to vl.c and
> include/sysemu/sysemu.h (and make it always true in
> stubs/machine-init-done.c)?
> 
> Then muxes_realized can go away too.

Sure!  I'll add a new patch for it.  Thanks,