On Thu, Mar 01, 2018 at 04:44:30PM +0800, Peter Xu wrote: > TCP chardevs can be using QIO network listeners working in the > background when in listening mode. However the network listeners are > always running in main context. This can race with chardevs that are > running in non-main contexts. > > To solve this, we need to re-setup the net listeners in > tcp_chr_update_read_handler() with the newly cached gcontext. > > Since at it, generalize a tcp_chr_net_listener_setup() helper function > and clean up the old code a bit. > > Signed-off-by: Peter Xu <pet...@redhat.com> > --- > chardev/char-socket.c | 32 ++++++++++++++++++++++++++------ > 1 file changed, 26 insertions(+), 6 deletions(-) > > diff --git a/chardev/char-socket.c b/chardev/char-socket.c > index 43a2cc2c1c..5cd20cc932 100644 > --- a/chardev/char-socket.c > +++ b/chardev/char-socket.c > @@ -410,6 +410,19 @@ static void update_disconnected_filename(SocketChardev > *s) > s->is_listen, s->is_telnet); > } > > +/* Set enable=true to start net listeners, false to stop them. */ > +static void tcp_chr_net_listener_setup(SocketChardev *s, bool enable) > +{ > + Chardev *chr = CHARDEV(s); > + > + /* Net listeners' context will follow the Chardev's. */ > + qio_net_listener_set_client_func_full(s->listener, > + enable ? tcp_chr_accept : NULL, > + enable ? chr : NULL, > + NULL, > + chr->gcontext);
I don't think this helper method is really a benefit. In fact I think it makes understanding the code harder, because when you see tcp_chr_net_listener_setup(s, true), you've no idea what 'true' means without going to finding the impl of tcp_chr_net_listener_setup(). Just leave the direct calls to qio_net_listener_set_client_func_full as they are IMHO. > +} > + > /* NB may be called even if tcp_chr_connect has not been > * reached, due to TLS or telnet initialization failure, > * so can *not* assume s->connected == true > @@ -422,8 +435,7 @@ static void tcp_chr_disconnect(Chardev *chr) > tcp_chr_free_connection(chr); > > if (s->listener) { > - qio_net_listener_set_client_func(s->listener, tcp_chr_accept, > - chr, NULL); > + tcp_chr_net_listener_setup(s, true); > } > update_disconnected_filename(s); > if (emit_close) { > @@ -559,6 +571,15 @@ static void tcp_chr_update_read_handler(Chardev *chr) > { > SocketChardev *s = SOCKET_CHARDEV(chr); > > + if (s->listener) { > + /* > + * It's possible that chardev context is changed in > + * qemu_chr_be_update_read_handlers(). Reset it for QIO net > + * listener if there is. > + */ > + tcp_chr_net_listener_setup(s, true); > + } > + > if (!s->connected) { > return; > } > @@ -742,7 +763,7 @@ static int tcp_chr_new_client(Chardev *chr, > QIOChannelSocket *sioc) > qio_channel_set_delay(s->ioc, false); > } > if (s->listener) { > - qio_net_listener_set_client_func(s->listener, NULL, NULL, NULL); > + tcp_chr_net_listener_setup(s, false); > } > > if (s->tls_creds) { > @@ -823,7 +844,7 @@ static void char_socket_finalize(Object *obj) > tcp_chr_reconn_timer_cancel(s); > qapi_free_SocketAddress(s->addr); > if (s->listener) { > - qio_net_listener_set_client_func(s->listener, NULL, NULL, NULL); > + tcp_chr_net_listener_setup(s, false); > object_unref(OBJECT(s->listener)); > } > if (s->tls_creds) { > @@ -979,8 +1000,7 @@ static void qmp_chardev_open_socket(Chardev *chr, > return; > } > if (!s->ioc) { > - qio_net_listener_set_client_func(s->listener, tcp_chr_accept, > - chr, NULL); > + tcp_chr_net_listener_setup(s, true); > } > } else if (qemu_chr_wait_connected(chr, errp) < 0) { > goto error; > -- > 2.14.3 > Regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|