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Date: Mon, 10 Mar 2014 20:02:56 +0100
From: Stefan Hajnoczi <stefanha@redhat.com>
Message-ID: <20140310190256.GA12263@stefanha-thinkpad.redhat.com>
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Subject: Re: [Qemu-devel] [PATCH 1/2] tests/libqtest: Fix possible deadlock
 in qtest initialization
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To: Marcel Apfelbaum <marcel.a@redhat.com>
Cc: armbru@redhat.com, qemu-devel@nongnu.org, aliguori@amazon.com, afaerber@suse.de

On Mon, Mar 10, 2014 at 02:12:13PM +0200, Marcel Apfelbaum wrote:
> @@ -123,6 +125,11 @@ QTestState *qtest_init(const char *extra_args)
>      sock = init_socket(socket_path);
>      qmpsock = init_socket(qmp_socket_path);
>  
> +    setsockopt(sock, SOL_SOCKET, SO_RCVTIMEO, (void *)&socket_timeout,
> +               sizeof(socket_timeout));
> +    setsockopt(qmpsock, SOL_SOCKET, SO_RCVTIMEO, (void *)&socket_timeout,
> +               sizeof(socket_timeout));
> +

Please move this into socket_accept() so qtest_init() doesn't need to
know about setsockopt() details.  It should just get an fd or -errno
return value from socket_accept()...

>      s->fd = socket_accept(sock);
> -    s->qmp_fd = socket_accept(qmpsock);
> +    if (s->fd >= 0) {
> +        s->qmp_fd = socket_accept(qmpsock);
> +    }
>      unlink(socket_path);
>      unlink(qmp_socket_path);

...then you can ensure that we unlink the sockets even on failure.

And then something like g_assert(s->fd >= 0 && s->qmp_fd >= 0) would be
fine.  The process can abort() at this point.