From mboxrd@z Thu Jan  1 00:00:00 1970
From: Jakub Kicinski <kubakici@wp.pl>
Subject: Re: [PATCH net-next] libbpf: add function to setup XDP
Date: Sat, 9 Dec 2017 15:57:15 -0800
Message-ID: <20171209155715.78ef02e1@cakuba.netronome.com>
References: <20171209144315.25890-1-eric@regit.org>
Mime-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
Content-Transfer-Encoding: 7bit
Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
        ast@kernel.org, daniel@iogearbox.net
To: Eric Leblond <eric@regit.org>
Return-path: <linux-kernel-owner@vger.kernel.org>
In-Reply-To: <20171209144315.25890-1-eric@regit.org>
Sender: linux-kernel-owner@vger.kernel.org
List-Id: netdev.vger.kernel.org

On Sat,  9 Dec 2017 15:43:15 +0100, Eric Leblond wrote:
> +	for (nh = (struct nlmsghdr *)buf; NLMSG_OK(nh, len);
> +	     nh = NLMSG_NEXT(nh, len)) {
> +		if (nh->nlmsg_pid != getpid()) {
> +			ret = -LIBBPF_ERRNO__WRNGPID;
> +			goto cleanup;
> +		}
> +		if (nh->nlmsg_seq != seq) {
> +			ret = -LIBBPF_ERRNO__INVSEQ;
> +			goto cleanup;
> +		}
> +		switch (nh->nlmsg_type) {
> +		case NLMSG_ERROR:
> +			err = (struct nlmsgerr *)NLMSG_DATA(nh);
> +			if (!err->error)
> +				continue;
> +			ret = err->error;
> +			goto cleanup;
> +		case NLMSG_DONE:
> +			break;
> +		default:
> +			break;
> +		}

Would it be possible to print out or preferably return to the caller
the ext ack error message?  A couple of drivers are using it for XDP
mis-configuration reporting instead of printks.  We should encourage
other to do the same and support it in all user space since ext ack 
msgs lead to much better user experience.