[Spice-devel] [PATCH spice-server v4 0/4] Better handling reset for streaming device

[Uri Lublin]

On 01/30/2018 04:33 PM, Christophe de Dinechin wrote:
> 
> Christophe de Dinechin writes:
> 
>>> On 30 Jan 2018, at 12:56, Frediano Ziglio <fziglio at redhat.com> wrote:
>>>
>>>>
>>>> Hi Frediano,
>>>>
>>>>
>>>>
>>>>> On 30 Jan 2018, at 11:50, Frediano Ziglio <fziglio at redhat.com> wrote:
>>>>>
>>>>> ping the series
>>>>
>>>> I’m currently looking at it. Is it supposed to fix the read errors I had when
>>>> restarting the streaming agent?
>>>>
>>>
>>> Yes, make the reset more stable.
>>> When you close the device the state will be more consistent allowing
>>> basically to kill the process using the device in any state and opening
>>> again. Obviously if you continue to send wrong commands the device will
>>> keep rejecting them.
>>>
>>> I tried to reproduce the issues reported on IRC and these helped me,
>>> now I avoid entirely to reboot the guest.
>>
>> OK, right now I get a QEMU crash whenever I do any kind of activity
>> (the keyboard seems to be what triggers it).
>>
>> I’m trying to reproduce on master to see if your patch is the cause.
>> That host has gone through some unusual nastiness, and may be
>> in a geborked state.
> 
> Reverting the server to master, I am back to the behavior I had before,
> where the same series of events leads to
> 
> DISPLAY=:1 spice-streaming-agent -c noblock=yes
> spice-streaming-agent[2240]: UNKNOWN msg of type 5
> spice-streaming-agent[2240]: BAD VERSION 0 (expected is 1)
> spice-streaming-agent[2240]: BAD VERSION 108 (expected is 1)
> spice-streaming-agent[2240]: BAD VERSION 97 (expected is 1)
> spice-streaming-agent[2240]: read command from device FAILED -- read 1 expected 8
> spice-streaming-agent[2240]: FAILED to read command


Hi Christophe,

There are some problems here:
1. (I guess) your spice-streaming-agent sends CURSOR messages
    which currently the spice-server does not know to handle.
    (Frediano sent patches for that but still no review).

    For now try to comment out the code in spice-streaming-agent
    that sends CURSOR commands.

2. spice-server gets an unknown command. It sends a message to the
    spice-streaming-agent to let it know the server read an invalid
    message. spice-streaming-agent is missing a code to handle such
    a message.

    This should be fixed.

3. When such messages are in play, they are not fully read (code
    breaks after reading the header). This makes the spice-server
    and spice-streaming-agent go out of sync).

    This may be fixed. I'm not sure we can recover
    all errors, and perhaps the right thing to do is sync
    with close/open of the virtio-serial-port.
    However reading the whole message (if it's not too big) should
    at least keep the server/agent synchronized, even if an unknown
    message encountered.

Regards,
     Uri.