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Date: Tue, 01 Dec 2009 12:54:42 -0600
From: Anthony Liguori <anthony@codemonkey.ws>
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Subject: Re: [Qemu-devel] Socket reconnection.
References: <4B0DCC45.5080308@collabora.co.uk> <4B13FE66.2080401@codemonkey.ws>
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To: "Krumme, Chris" <Chris.Krumme@windriver.com>
Cc: Ian Molton <ian.molton@collabora.co.uk>, qemu-devel@nongnu.org

Krumme, Chris wrote:
> Hello Ian,
>
> Since you did not inline your source I will paste in a chunk:
>
>
> @@ -2030,10 +2036,18 @@ static void tcp_chr_read(void *opaque)
>          if (s->listen_fd >= 0) {
>              qemu_set_fd_handler(s->listen_fd, tcp_chr_accept, NULL,
> chr);
>          }
> -        qemu_set_fd_handler(s->fd, NULL, NULL, NULL);
> +        if (!s->reconnect)
> +            qemu_set_fd_handler(s->fd, NULL, NULL, NULL);
>          closesocket(s->fd);
>          s->fd = -1;
> -        qemu_chr_event(chr, CHR_EVENT_CLOSED);
> +        if (!s->reconnect) {
> +            qemu_chr_event(chr, CHR_EVENT_CLOSED);
> +        } else {
> +            do {
> +                sleep(s->reconnect);
> +            } while(!qemu_chr_connect_socket(s));
> +            qemu_chr_event(chr, CHR_EVENT_RECONNECTED);
> +        }
>      } else if (size > 0) {
>          if (s->do_telnetopt)
>              tcp_chr_process_IAC_bytes(chr, s, buf, &size);
>
>
> Should you be introducing a while sleep loop into Qemu here?
>
> I would think you should be returning 'no data', maybe after trying
> once.
>
> Hope this helps.
>
> Chris
>   

sleep() in qemu is very, very wrong.  It will pause the guest's 
execution and all sorts of badness can ensue.

The right thing to do is set a timer and not generate data while 
disconnected.  I still am not confident this is really a great thing to do.

Regards,

Anthony Liguori