Re: [PATCH 1/3] IB: new common API for draining a queue pair

[Leon Romanovsky <leon-2ukJVAZIZ/Y@public.gmane.org>]

On Fri, Feb 05, 2016 at 01:13:16PM -0800, Steve Wise wrote:
> From: Steve Wise <swise-7bPotxP6k4+P2YhJcF5u+p6NamaJ0bNTAL8bYrjMMd8@public.gmane.org>
> 
> Add provider-specific drain_qp function for providers needing special
> drain logic.
> 
> Add static function __ib_drain_qp() which posts noop WRs to the RQ and
> SQ and blocks until their completions are processed.  This ensures the
> applications completions have all been processed.
> 
> Add API function ib_drain_qp() which calls the provider-specific drain
> if it exists or __ib_drain_qp().
> 
> Signed-off-by: Steve Wise <swise-7bPotxP6k4+P2YhJcF5u+vpXobYPEAuW@public.gmane.org>
> ---
>  drivers/infiniband/core/verbs.c | 72 +++++++++++++++++++++++++++++++++++++++++
>  include/rdma/ib_verbs.h         |  2 ++
>  2 files changed, 74 insertions(+)
> 

 ...

> +	ret = ib_modify_qp(qp, &attr, IB_QP_STATE);
> +	if (ret) {
> +		WARN_ONCE(ret, "failed to drain QP: %d\n", ret);
> +		return;
> +	}
> +
> +	ret = ib_post_recv(qp, &rwr, &bad_rwr);
> +	if (ret) {
> +		WARN_ONCE(ret, "failed to drain recv queue: %d\n", ret);
> +		return;
> +	}
> +
> +	ret = ib_post_send(qp, &swr, &bad_swr);
> +	if (ret) {
> +		WARN_ONCE(ret, "failed to drain send queue: %d\n", ret);
> +		return;

You are returning here despite the fact that recv queue drained
successfully and you can wait for completion of rdrain safely.
Is it done on purpose?

> +	}
> +
> +	wait_for_completion(&rdrain.done);
> +	wait_for_completion(&sdrain.done);
> +}
> +
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