Re: [PATCH v9 07/20] multi-process: define transmission functions in remote

[Stefan Hajnoczi <stefanha@redhat.com>]

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On Thu, Aug 27, 2020 at 11:12:18AM -0700, elena.ufimtseva@oracle.com wrote:
> TODO: Avoid the aio_poll by entering the co-routines
> from the higher level to avoid aio_poll.

The monitor is unresponsive during the aio_poll() loop. Is this a
blocker for you?

Running all mpqemu communication in a coroutine as mentioned in this
TODO is a cleaner solution. Then this patch will be unnecessary.

> +static void coroutine_fn mpqemu_msg_send_co(void *data)
> +{
> +    MPQemuRequest *req = (MPQemuRequest *)data;
> +    Error *local_err = NULL;
> +
> +    mpqemu_msg_send(req->msg, req->ioc, &local_err);
> +    if (local_err) {
> +        error_report("ERROR: failed to send command to remote %d, ",
> +                     req->msg->cmd);
> +        req->finished = true;
> +        req->error = -EINVAL;
> +        return;

local_err is leaked.

> +    }
> +
> +    req->finished = true;
> +}
> +
> +void mpqemu_msg_send_in_co(MPQemuRequest *req, QIOChannel *ioc,
> +                                  Error **errp)
> +{
> +    Coroutine *co;
> +
> +    if (!req->ioc) {
> +        if (errp) {
> +            error_setg(errp, "Channel is set to NULL");
> +        } else {
> +            error_report("Channel is set to NULL");
> +        }

The caller should provide an errp if they are interested in the error
message. Duplicating error messages is messy.

> +static void coroutine_fn mpqemu_msg_recv_co(void *data)
> +{
> +    MPQemuRequest *req = (MPQemuRequest *)data;
> +    Error *local_err = NULL;
> +
> +    mpqemu_msg_recv(req->msg, req->ioc, &local_err);
> +    if (local_err) {
> +        error_report("ERROR: failed to send command to remote %d, ",
> +                     req->msg->cmd);
> +        req->finished = true;
> +        req->error = -EINVAL;
> +        return;

local_err is leaked.

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