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Re: [Qemu-devel] [PATCH v4 for-4.0 1/7] char-socket: Enable "nowait" opt
From: |
Yury Kotov |
Subject: |
Re: [Qemu-devel] [PATCH v4 for-4.0 1/7] char-socket: Enable "nowait" option on client sockets |
Date: |
Tue, 15 Jan 2019 19:53:51 +0300 |
15.01.2019, 18:39, "Daniel P. Berrangé" <address@hidden>:
> On Fri, Jan 11, 2019 at 04:36:11PM +0800, Yongji Xie wrote:
>> On Fri, 11 Jan 2019 at 16:32, Daniel P. Berrangé <address@hidden> 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 <address@hidden> wrote:
>> > > >
>> > > > 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.
>
> It took me rather longer than expected to fully debug all scenarios, but
> I've finally sent patches:
>
> https://lists.gnu.org/archive/html/qemu-devel/2019-01/msg03344.html
>
> Regards,
> Daniel
> --
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I didn't do a deep review and may be wrong, but I think the race is still
possible in the hotplug case.
Example:
1. User adds a chardev (qmp: chardev-add) with 'reconnect' option;
2. Some main-loop iterations...
3. Reconnect timer triggers and starts connection thread;
4. User adds a vhost-user-blk (qmp: device-add): device realize ->
wait_connected.
Here, there is a chance that we are in the wait_connected and the connection
thread is still running.
Regards,
Yury
- Re: [Qemu-devel] [PATCH v4 for-4.0 1/7] char-socket: Enable "nowait" option on client sockets, (continued)
- Re: [Qemu-devel] [PATCH v4 for-4.0 1/7] char-socket: Enable "nowait" option on client sockets, Yongji Xie, 2019/01/10
- Re: [Qemu-devel] [PATCH v4 for-4.0 1/7] char-socket: Enable "nowait" option on client sockets, Daniel P . Berrangé, 2019/01/10
- Re: [Qemu-devel] [PATCH v4 for-4.0 1/7] char-socket: Enable "nowait" option on client sockets, Yongji Xie, 2019/01/10
- Re: [Qemu-devel] [PATCH v4 for-4.0 1/7] char-socket: Enable "nowait" option on client sockets, Daniel P . Berrangé, 2019/01/10
- Re: [Qemu-devel] [PATCH v4 for-4.0 1/7] char-socket: Enable "nowait" option on client sockets, Yongji Xie, 2019/01/10
- Re: [Qemu-devel] [PATCH v4 for-4.0 1/7] char-socket: Enable "nowait" option on client sockets, Daniel P . Berrangé, 2019/01/10
- Re: [Qemu-devel] [PATCH v4 for-4.0 1/7] char-socket: Enable "nowait" option on client sockets, Yongji Xie, 2019/01/11
- Re: [Qemu-devel] [PATCH v4 for-4.0 1/7] char-socket: Enable "nowait" option on client sockets, Daniel P . Berrangé, 2019/01/11
- Re: [Qemu-devel] [PATCH v4 for-4.0 1/7] char-socket: Enable "nowait" option on client sockets, Yongji Xie, 2019/01/11
- Re: [Qemu-devel] [PATCH v4 for-4.0 1/7] char-socket: Enable "nowait" option on client sockets, Daniel P . Berrangé, 2019/01/15
- Re: [Qemu-devel] [PATCH v4 for-4.0 1/7] char-socket: Enable "nowait" option on client sockets,
Yury Kotov <=
- Re: [Qemu-devel] [PATCH v4 for-4.0 1/7] char-socket: Enable "nowait" option on client sockets, Daniel P . Berrangé, 2019/01/15
- Re: [Qemu-devel] [PATCH v4 for-4.0 1/7] char-socket: Enable "nowait" option on client sockets, Yongji Xie, 2019/01/16
[Qemu-devel] [PATCH v4 for-4.0 2/7] vhost-user: Support transferring inflight buffer between qemu and backend, elohimes, 2019/01/09
[Qemu-devel] [PATCH v4 for-4.0 3/7] libvhost-user: Introduce vu_queue_map_desc(), elohimes, 2019/01/09
[Qemu-devel] [PATCH v4 for-4.0 4/7] libvhost-user: Support tracking inflight I/O in shared memory, elohimes, 2019/01/09