Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Date:   Mon, 31 Jul 2023 19:43:36 -0700
From:   Jakub Kicinski <kuba@kernel.org>
To:     Leon Hwang <hffilwlqm@gmail.com>
Cc:     ast@kernel.org, daniel@iogearbox.net, john.fastabend@gmail.com,
        andrii@kernel.org, martin.lau@linux.dev, song@kernel.org,
        yonghong.song@linux.dev, kpsingh@kernel.org, sdf@google.com,
        haoluo@google.com, jolsa@kernel.org, davem@davemloft.net,
        edumazet@google.com, pabeni@redhat.com, hawk@kernel.org,
        rostedt@goodmis.org, mhiramat@kernel.org, mykolal@fb.com,
        shuah@kernel.org, tangyeechou@gmail.com, kernel-patches-bot@fb.com,
        bpf@vger.kernel.org, linux-kernel@vger.kernel.org,
        netdev@vger.kernel.org, linux-trace-kernel@vger.kernel.org,
        linux-kselftest@vger.kernel.org
Subject: Re: [PATCH bpf-next v4 1/2] bpf, xdp: Add tracepoint to xdp
 attaching failure
Message-ID: <20230731194336.5b4bd065@kernel.org>
In-Reply-To: <20230730114951.74067-2-hffilwlqm@gmail.com>
References: <20230730114951.74067-1-hffilwlqm@gmail.com>
        <20230730114951.74067-2-hffilwlqm@gmail.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
Content-Transfer-Encoding: 7bit
Precedence: bulk

On Sun, 30 Jul 2023 19:49:50 +0800 Leon Hwang wrote:
> @@ -9472,6 +9473,7 @@ int bpf_xdp_link_attach(const union bpf_attr *attr, struct bpf_prog *prog)
>  	struct bpf_link_primer link_primer;
>  	struct bpf_xdp_link *link;
>  	struct net_device *dev;
> +	struct netlink_ext_ack extack;

This is not initialized. Also, while fixing that, move it up 
to maintain the line order by decreasing line length.

>  	int err, fd;
>  
>  	rtnl_lock();
> @@ -9497,12 +9499,13 @@ int bpf_xdp_link_attach(const union bpf_attr *attr, struct bpf_prog *prog)
>  		goto unlock;
>  	}
>  
> -	err = dev_xdp_attach_link(dev, NULL, link);
> +	err = dev_xdp_attach_link(dev, &extack, link);
>  	rtnl_unlock();
>  
>  	if (err) {
>  		link->dev = NULL;
>  		bpf_link_cleanup(&link_primer);
> +		trace_bpf_xdp_link_attach_failed(extack._msg);