On Fri, 11 Jan 2019 at 16:32, Daniel P. Berrangé <berra...@redhat.com> wrote: > > On Fri, Jan 11, 2019 at 03:50:40PM +0800, Yongji Xie wrote: > > On Fri, 11 Jan 2019 at 00:41, Daniel P. Berrangé <berra...@redhat.com> > > wrote: > > > > > > On Thu, Jan 10, 2019 at 10:29:20PM +0800, Yongji Xie wrote: > > > > On Thu, 10 Jan 2019 at 22:11, Daniel P. Berrangé <berra...@redhat.com> > > > > wrote: > > > > > > > > > > On Thu, Jan 10, 2019 at 10:08:54PM +0800, Yongji Xie wrote: > > > > > > On Thu, 10 Jan 2019 at 21:24, Daniel P. Berrangé > > > > > > <berra...@redhat.com> wrote: > > > > > > > > > > > > > > On Thu, Jan 10, 2019 at 09:19:41PM +0800, Yongji Xie wrote: > > > > > > > > On Thu, 10 Jan 2019 at 20:50, Daniel P. Berrangé > > > > > > > > <berra...@redhat.com> wrote: > > > > > > > > > > > > > > > > > > On Wed, Jan 09, 2019 at 07:27:22PM +0800, elohi...@gmail.com > > > > > > > > > wrote: > > > > > > > > > > From: Xie Yongji <xieyon...@baidu.com> > > > > > > > > > > > > > > > > > > > > Enable "nowait" option to make QEMU not do a connect > > > > > > > > > > on client sockets during initialization of the chardev. > > > > > > > > > > Then we can use qemu_chr_fe_wait_connected() to connect > > > > > > > > > > when necessary. Now it would be used for unix domain > > > > > > > > > > socket of vhost-user-blk device to support reconnect. > > > > > > > > > > > > > > > > > > > > Signed-off-by: Xie Yongji <xieyon...@baidu.com> > > > > > > > > > > Signed-off-by: Zhang Yu <zhangy...@baidu.com> > > > > > > > > > > --- > > > > > > > > > > chardev/char-socket.c | 56 > > > > > > > > > > +++++++++++++++++++++---------------------- > > > > > > > > > > qapi/char.json | 3 +-- > > > > > > > > > > qemu-options.hx | 9 ++++--- > > > > > > > > > > 3 files changed, 35 insertions(+), 33 deletions(-) > > > > > > > > > > > > > > > > > > > > diff --git a/chardev/char-socket.c b/chardev/char-socket.c > > > > > > > > > > index eaa8e8b68f..f803f4f7d3 100644 > > > > > > > > > > --- a/chardev/char-socket.c > > > > > > > > > > +++ b/chardev/char-socket.c > > > > > > > > > > @@ -1072,37 +1072,37 @@ static void > > > > > > > > > > qmp_chardev_open_socket(Chardev *chr, > > > > > > > > > > s->reconnect_time = reconnect; > > > > > > > > > > } > > > > > > > > > > > > > > > > > > > > - if (s->reconnect_time) { > > > > > > > > > > - tcp_chr_connect_async(chr); > > > > > > > > > > - } else { > > > > > > > > > > - if (s->is_listen) { > > > > > > > > > > - char *name; > > > > > > > > > > - s->listener = qio_net_listener_new(); > > > > > > > > > > + if (s->is_listen) { > > > > > > > > > > + char *name; > > > > > > > > > > + s->listener = qio_net_listener_new(); > > > > > > > > > > > > > > > > > > > > - name = > > > > > > > > > > g_strdup_printf("chardev-tcp-listener-%s", chr->label); > > > > > > > > > > - qio_net_listener_set_name(s->listener, name); > > > > > > > > > > - g_free(name); > > > > > > > > > > + name = g_strdup_printf("chardev-tcp-listener-%s", > > > > > > > > > > chr->label); > > > > > > > > > > + qio_net_listener_set_name(s->listener, name); > > > > > > > > > > + g_free(name); > > > > > > > > > > > > > > > > > > > > - if (qio_net_listener_open_sync(s->listener, > > > > > > > > > > s->addr, errp) < 0) { > > > > > > > > > > - object_unref(OBJECT(s->listener)); > > > > > > > > > > - s->listener = NULL; > > > > > > > > > > - goto error; > > > > > > > > > > - } > > > > > > > > > > + if (qio_net_listener_open_sync(s->listener, > > > > > > > > > > s->addr, errp) < 0) { > > > > > > > > > > + object_unref(OBJECT(s->listener)); > > > > > > > > > > + s->listener = NULL; > > > > > > > > > > + goto error; > > > > > > > > > > + } > > > > > > > > > > > > > > > > > > > > - qapi_free_SocketAddress(s->addr); > > > > > > > > > > - s->addr = > > > > > > > > > > socket_local_address(s->listener->sioc[0]->fd, errp); > > > > > > > > > > - update_disconnected_filename(s); > > > > > > > > > > + qapi_free_SocketAddress(s->addr); > > > > > > > > > > + s->addr = > > > > > > > > > > socket_local_address(s->listener->sioc[0]->fd, errp); > > > > > > > > > > + update_disconnected_filename(s); > > > > > > > > > > > > > > > > > > > > - if (is_waitconnect && > > > > > > > > > > - qemu_chr_wait_connected(chr, errp) < 0) { > > > > > > > > > > - return; > > > > > > > > > > - } > > > > > > > > > > - if (!s->ioc) { > > > > > > > > > > - > > > > > > > > > > qio_net_listener_set_client_func_full(s->listener, > > > > > > > > > > - > > > > > > > > > > tcp_chr_accept, > > > > > > > > > > - chr, > > > > > > > > > > NULL, > > > > > > > > > > - > > > > > > > > > > chr->gcontext); > > > > > > > > > > - } > > > > > > > > > > + if (is_waitconnect && > > > > > > > > > > + qemu_chr_wait_connected(chr, errp) < 0) { > > > > > > > > > > + return; > > > > > > > > > > + } > > > > > > > > > > + if (!s->ioc) { > > > > > > > > > > + > > > > > > > > > > qio_net_listener_set_client_func_full(s->listener, > > > > > > > > > > + > > > > > > > > > > tcp_chr_accept, > > > > > > > > > > + chr, > > > > > > > > > > NULL, > > > > > > > > > > + > > > > > > > > > > chr->gcontext); > > > > > > > > > > + } > > > > > > > > > > + } else if (is_waitconnect) { > > > > > > > > > > + if (s->reconnect_time) { > > > > > > > > > > + tcp_chr_connect_async(chr); > > > > > > > > > > } else if (qemu_chr_wait_connected(chr, errp) < 0) > > > > > > > > > > { > > > > > > > > > > goto error; > > > > > > > > > > } > > > > > > > > > > > > > > > > > > This skips everything when 'is_waitconnect' is false. > > > > > > > > > > > > > > > > > > This combines with a bug in tests/libqtest.c which adds the > > > > > > > > > 'nowait' > > > > > > > > > flag to the -chardevs it cteates. This mistake was previously > > > > > > > > > ignored > > > > > > > > > because the chardevs were socket clients, but now we honour > > > > > > > > > it. > > > > > > > > > > > > > > > > > > We shoul remove 'nowait' from the qtest chardevs, but > > > > > > > > > separately > > > > > > > > > from that this code should also still attempt a non-blocking > > > > > > > > > connect when is_waitconnect is false. > > > > > > > > > > > > > > > > > > > > > > > > > Do you mean we still need to connect server in background with > > > > > > > > "nowait" option? But my purpose is not to connect server until > > > > > > > > we > > > > > > > > manually call qemu_chr_fe_wait_connected() in other place. > > > > > > > > > > > > > > I don't see a need to delay the connect. We can start a > > > > > > > background connect right away. The later code you have > > > > > > > merely needs to wait for that background connect to > > > > > > > finish, which qemu_chr_fe_wait_connected still accomplishes. > > > > > > > This keeps the chardev code clearer only having 2 distinct > > > > > > > code paths to worry about - blocking or non-blocking connect. > > > > > > > > > > > > > > > > > > > Now the problem is that we have a server that only accept one > > > > > > connection. And we want to read something from it during device > > > > > > initializtion. > > > > > > > > > > > > If background connect it before we call qemu_chr_fe_wait_connected() > > > > > > during device initializtion, qemu_chr_fe_wait_connected() will > > > > > > accomplish but we can't read anything. And we have no way to release > > > > > > the background connection. So what I want to do in this patch is to > > > > > > disable background connect. > > > > > > > > > > I'm not seeing the problem here. What I proposed results in > > > > > > > > > > 1. chardev starts connect() > > > > > > > > This should be asynchronous with "reconnect" option. Another thread > > > > may connect before vhost backend? > > > > > > > > > 2. vhost backend waits for connect() to complete > > > > > > > > Sorry, I'm not sure I get your point here. Do you mean vhost backend > > > > call qemu_chr_fe_wait_connected()? Seems like > > > > qemu_chr_fe_wait_connected() will connect directly rather than wait > > > > for connect() to complete? > > > > > > Ahhhh, yes, you are right. > > > > > > qemu_chr_fe_wait_connected will potentially cause a second connection to > > > be established > > > > > > Looking at it the qemu_chr_fe_wait_connected() I believe it is seriously > > > broken even before this patch series. > > > > > > The intended usage is that a device can all qemu_chr_fe_wait_connected > > > to wait for a new connection to be established, and then do I/O on the > > > chardev. This does not in fact work if TLS, websock or telnet modes > > > are enabled for the socket, due to a mistake introduced when we previously > > > tried to fix this: > > > > > > 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 > > > > > > That commit fixed the problem where we continued to accept() new sockets > > > when TLS/telnet was enabled, because the 's->connected' flag isn't set > > > immediately. > > > > > > Unfortunately what this means is that when qemu_chr_fe_wait_connected > > > returns, the chardev is *not* ready to read/write data. The TLS/telnet > > > handshake has not been run, and is still pending in the background. > > > > > > So we'll end up with device backend trying todo I/O on the chardev > > > at the same time as it is trying todo the TLS/telnet handshake. > > > > > > We need to fix qemu_chr_fe_wait_connected so that it does explicit > > > synchronization wrt to any ongoing background connection process. > > > It must only return once all TLS/telnet/websock handshakes have > > > completed. If we fix that correctly, then I believe it will also > > > solve the problem you're trying to address. > > > > > > > Yes, I think this should be the right way to go. To fix it, my thought > > is to track the async QIOChannelSocket in SocketChardev. Then we can > > easily get the connection progress in qemu_chr_fe_wait_connected(). Do > > you have any suggestion? > > I've got a few patches that refactor the code to fix this. I'll send them > today and CC you on them. >
That would be great! Thank you. Thanks, Yongji