Re: [Qemu-devel] [PATCH v1 1/4] vhost-user: Add ability to know vhost-user backend disconnection

[Tetsuya Mukawa <mukawa@igel.co.jp>]

On 2015/06/15 22:32, Stefan Hajnoczi wrote:
> On Fri, May 29, 2015 at 01:42:27PM +0900, Tetsuya Mukawa wrote:
>> Current QEMU cannot detect vhost-user backend disconnection. The
>> patch adds ability to know it.
>> To know disconnection, add watcher to detect G_IO_HUP event. When
>> G_IO_HUP event is detected, the disconnected socket will be read
>> to cause a CHR_EVENT_CLOSED.
>>
>> Signed-off-by: Tetsuya Mukawa <mukawa@igel.co.jp>
>> ---
>>  net/vhost-user.c | 14 ++++++++++++++
>>  1 file changed, 14 insertions(+)
> It is unfortunate that qemu-chr.c doesn't have a built-in way to handle
> G_IO_HUP and raise the CHR_EVENT_CLOSED event.  This is not really
> specific to vhost-user.
>
> CCing Paolo Bonzini (Character Devices).  He is currently on vacation so
> let's not hold up this patch.  It can be made generic later, if
> necessary.
>
>> diff --git a/net/vhost-user.c b/net/vhost-user.c
>> index 11899c5..1967ff4 100644
>> --- a/net/vhost-user.c
>> +++ b/net/vhost-user.c
>> @@ -19,6 +19,7 @@ typedef struct VhostUserState {
>>      NetClientState nc;
>>      CharDriverState *chr;
>>      VHostNetState *vhost_net;
>> +    int watch;
>>  } VhostUserState;
>>  
>>  typedef struct VhostUserChardevProps {
>> @@ -113,12 +114,23 @@ static void net_vhost_link_down(VhostUserState *s, bool link_down)
>>      }
>>  }
>>  
>> +static gboolean net_vhost_user_watch(GIOChannel *chan, GIOCondition cond,
>> +                                           void *opaque)
>> +{
>> +    VhostUserState *s = opaque;
>> +    uint8_t buf[1];
>> +
>> +    qemu_chr_fe_read_all(s->chr, buf, sizeof(buf));
>> +    return FALSE;
>> +}
> If you respin this patch, please add a comment like:
>
> /* We don't actually want to read anything, but CHR_EVENT_CLOSED will be
>  * raised as a side-effect of the read.
>  */

I appreciate for your all comments.
I will add above comments in next patches.

Tetsuya