From mboxrd@z Thu Jan  1 00:00:00 1970
From: David Ahern <dsahern@gmail.com>
Subject: Re: [bpf-next V1-RFC PATCH 01/14] xdp: base API for new XDP rx-queue
 info concept
Date: Wed, 13 Dec 2017 19:34:40 -0700
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 <151316396600.14967.5648145904814220715.stgit@firesoul>
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Cc: netdev@vger.kernel.org, gospo@broadcom.com, bjorn.topel@intel.com,
        michael.chan@broadcom.com
To: Jesper Dangaard Brouer <brouer@redhat.com>,
        Daniel Borkmann <borkmann@iogearbox.net>,
        Alexei Starovoitov <alexei.starovoitov@gmail.com>
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On 12/13/17 4:19 AM, Jesper Dangaard Brouer wrote:
> +
> +void xdp_rxq_info_unreg(struct xdp_rxq_info *xdp_rxq)
> +{
> +	xdp_rxq->reg_state = REG_STATE_UNREGISTRED;
> +}
> +EXPORT_SYMBOL_GPL(xdp_rxq_info_unreg);
> +
> +void xdp_rxq_info_init(struct xdp_rxq_info *xdp_rxq)
> +{
> +	if (xdp_rxq->reg_state == REG_STATE_REGISTRED) {
> +		WARN(1, "Missing unregister, handled but fix driver\n");
> +		xdp_rxq_info_unreg(xdp_rxq);
> +	}
> +	memset(xdp_rxq, 0, sizeof(*xdp_rxq));
> +	xdp_rxq->queue_index = U32_MAX;
> +	xdp_rxq->reg_state = REG_STATE_NEW;
> +}
> +EXPORT_SYMBOL_GPL(xdp_rxq_info_init);
> +
> +void xdp_rxq_info_reg(struct xdp_rxq_info *xdp_rxq)
> +{
> +	WARN(!xdp_rxq->dev, "Missing net_device from driver");
> +	WARN(xdp_rxq->queue_index == U32_MAX, "Miss queue_index from driver");
> +	WARN(!(xdp_rxq->reg_state == REG_STATE_NEW),"API violation, miss init");
> +	xdp_rxq->reg_state = REG_STATE_REGISTRED;
> +}
> +EXPORT_SYMBOL_GPL(xdp_rxq_info_reg);
> 

Rather than WARN()'s why not make the _reg and _init functions return an
int that indicates an error? For example you don't want to continue if
the dev is expected but missing.