Subject: Re: [PATCH RFC iproute2-next 1/2] rdma: add 'link add/delete' commands

From: Leon Romanovsky <[email-masked]>
Date: Wed, 28 Nov 2018 22:02:04 +0200

On Wed, Nov 28, 2018 at 01:34:14PM -0600, Steve Wise wrote:
> ...
>
> >>> +	rd_prepare_msg(rd, RDMA_NLDEV_CMD_NEWLINK, &seq,
> >>> +		       (NLM_F_REQUEST | NLM_F_ACK));
> >>> +	mnl_attr_put_strz(rd->nlh, RDMA_NLDEV_ATTR_DEV_NAME, name);
> >>> +	mnl_attr_put_strz(rd->nlh, RDMA_NLDEV_ATTR_LINK_TYPE, type);
> >>> +	mnl_attr_put_strz(rd->nlh, RDMA_NLDEV_ATTR_NDEV_NAME, dev);
> >>> +	ret = rd_send_msg(rd);
> >>> +	if (ret)
> >>> +		return ret;
> >>> +
> >>> +	ret = rd_recv_msg(rd, link_add_parse_cb, rd, seq);
> >>> +	if (ret)
> >>> +		perror(NULL);
> >> Why do you need rd_recv_msg()? I think that it is not needed, at least
> >> for rename, I didn't need it.
> >> https://git.kernel.org/pub/scm/network/iproute2/iproute2-next.git/tree/rdma/dev.c#n244
> > To get the response of if it was successfully added.  It provides the
> > errno value.
> If I don't do the rd_recv_msg, then adding the same name twice fails
> without any error notification.  Ditto for deleting a non-existent
> link.  So the rd_recv_msg() allows getting the failure reason (and
> detecting the failure). 
>

Shouldn't extack provide such information as part of NLM_F_ACK flag?

just shooting into the air, will take more close look tomorrow.

Thanks