On Wed, Jan 16, 2019 at 01:54:54AM +0400, Marc-André Lureau wrote:
> On Tue, Jan 15, 2019 at 6:54 PM Daniel P. Berrangé <berra...@redhat.com>
> wrote:
> >
> > In the previous commit
> >
> > commit 1dc8a6695c731abb7461c637b2512c3670d82be4
> > Author: Marc-André Lureau <marcandre.lur...@redhat.com>
> > Date: Tue Aug 16 12:33:32 2016 +0400
> >
> > char: fix waiting for TLS and telnet connection
> >
> > the tcp_chr_wait_connected() method was changed to check for a non-NULL
> > 's->ioc' as a sign that there is already a connection present, as
> > opposed to checking the "connected" flag to supposedly fix handling of
> > TLS/telnet connections.
> >
> > The original code would repeatedly call tcp_chr_wait_connected creating
> > many connections as 'connected' would never become true. The changed
> > code would still repeatedly call tcp_chr_wait_connected busy waiting
> > because s->ioc is set but the chardev will never see CHR_EVENT_OPENED.
> > IOW, the code is still broken with TLS/telnet, but in a different way.
> >
> > Checking for a non-NULL 's->ioc' does not mean that a CHR_EVENT_OPENED
> > will be ready for a TLS/telnet connection. These protocols (and the
> > websocket protocol) all require the main loop to be running in order
> > to complete the protocol handshake before emitting CHR_EVENT_OPENED.
> > The tcp_chr_wait_connected() method is only used during early startup
> > before a main loop is running, so TLS/telnet/websock connections can
> > never complete initialization.
> >
> > Making this work would require changing tcp_chr_wait_connected to run
> > a main loop. This is quite complex since we must not allow GSource's
> > that other parts of QEMU have registered to run yet. The current callers
> > of tcp_chr_wait_connected do not require use of the TLS/telnet/websocket
> > protocols, so the simplest option is to just forbid this combination
> > completely for now.
> >
> > Signed-off-by: Daniel P. Berrangé <berra...@redhat.com>
>
> Reviewed-by: Marc-André Lureau <marcandre.lur...@redhat.com>
>
> > ---
> > chardev/char-socket.c | 16 ++++++++++++++--
> > 1 file changed, 14 insertions(+), 2 deletions(-)
> >
> > diff --git a/chardev/char-socket.c b/chardev/char-socket.c
> > index 91d775e9c5..7e98a95bbd 100644
> > --- a/chardev/char-socket.c
> > +++ b/chardev/char-socket.c
> > @@ -951,8 +951,20 @@ static void tcp_chr_accept_server_sync(Chardev *chr)
> > static int tcp_chr_wait_connected(Chardev *chr, Error **errp)
> > {
> > SocketChardev *s = SOCKET_CHARDEV(chr);
> > - /* It can't wait on s->connected, since it is set asynchronously
> > - * in TLS and telnet cases, only wait for an accepted socket */
> > + const char *opts[] = { "telnet", "tn3270", "websock", "tls-creds" };
> > + bool optset[] = { s->is_telnet, s->is_tn3270, s->is_websock,
> > s->tls_creds };
> > + size_t i;
> > +
> > + QEMU_BUILD_BUG_ON(G_N_ELEMENTS(opts) != G_N_ELEMENTS(optset));
> > + for (i = 0; i < G_N_ELEMENTS(opts); i++) {
> > + if (optset[i]) {
> > + error_setg(errp,
> > + "'%s' option is incompatible with waiting for "
> > + "connection during early startup", opts[i]);
>
> "during early startup" ? I think you could also reach this by using
> chardev-add & netdev_add.
Yes, I didn't realize that at first. It also means that patch 12 is in
fact still broken in the hotplug case.
Regards,
Daniel
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