Re: [Qemu-devel] [PATCH 07/18] migration: make writes blocking

[Markus Armbruster]

Juan Quintela <address@hidden> writes:

> Move all the writes to the migration_thread, and make writings
> blocking.  Notice that are still using the iothread for everything
> that we do.
[...]
> diff --git a/qemu-sockets.c b/qemu-sockets.c
> index cfed9c5..61b6e95 100644
> --- a/qemu-sockets.c
> +++ b/qemu-sockets.c
> @@ -276,9 +276,6 @@ static int inet_connect_addr(struct addrinfo *addr, bool 
> *in_progress,
>          return -1;
>      }
>      qemu_setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on));
> -    if (connect_state != NULL) {
> -        socket_set_nonblock(sock);
> -    }
>      /* connect to peer */
>      do {
>          rc = 0;
> @@ -732,7 +729,6 @@ int unix_connect_opts(QemuOpts *opts, Error **errp,
>          connect_state = g_malloc0(sizeof(*connect_state));
>          connect_state->callback = callback;
>          connect_state->opaque = opaque;
> -        socket_set_nonblock(sock);
>      }
>
>      memset(&un, 0, sizeof(un));

Doesn't this break inet_nonblocking_connect() and
unix_nonblocking_connect()?

In your cover letter, you wrote:

    Note: Writes has become blocking, and I have to change the "remove"
    the feature now in qemu-sockets.c.  Checked that migration was the
    only user of that feature.  If new users appear, they just need to add
    the socket_set_nonblock() by hand.

Yes, migration-{tcp,unix} are their only users, but if they want a
blocking socket now, why not use inet_connect() and unix_connect()?

New users can't "just add socket_set_nonblock()".  They'd have to add it
right where you deleted it: between qemu_socket() and connect().  Else
the connect() is blocking.

[...]