On 08/02/16 13:55, Daniel P. Berrange wrote: > In previous commit: > > commit f2001a7e0555b66d6db25a3ff1801540814045bb > Author: Daniel P. Berrange <berra...@redhat.com> > Date: Tue Jan 19 11:14:30 2016 +0000 > > char: don't assume telnet initialization will not block > > The code which writes the telnet initialization sequence moved > to an event loop callback. If the TCP chardev is opened as a > server in blocking mode (ie -serial telnet:0.0.0.0:3000,server,wait) > this results in a state where the TCP chardev is connected, but not > yet ready to send/recv data when virtual hardware is created. > > When the virtual hardware initialization registers its chardev > callbacks, it triggers tcp_chr_update_read_handler, which will > add I/O watches to the connection. > > When the telnet initialization finally runs, it will then call > tcp_chr_connect to finish the connection setup. This will in > turn add I/O watches to the connection too. > > There are now two sets of I/O watches registered on the same > connection. This ultimately causes data loss on the connection, > for example, when typing into the telnet console only every > second byte is echoed back to the client. > > The same flaw can affect channels running with TLS encryption > too, since they also have delayed connection setup completion. > > The fix is to update tcp_chr_update_read_handler so that it > avoids registering watches if the connection is not fully > setup yet. > > Signed-off-by: Daniel P. Berrange <berra...@redhat.com> > --- > qemu-char.c | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/qemu-char.c b/qemu-char.c > index 927c47e..9060f8a 100644 > --- a/qemu-char.c > +++ b/qemu-char.c > @@ -2856,6 +2856,10 @@ static void > tcp_chr_update_read_handler(CharDriverState *chr) > { > TCPCharDriver *s = chr->opaque; > > + if (!s->connected) { > + return; > + } > + > remove_fd_in_watch(chr); > if (s->ioc) { > chr->fd_in_tag = io_add_watch_poll(s->ioc, >
Hi Daniel, Yes I can confirm that this patch fixes the issue for me - thanks a lot for debugging! ATB, Mark.