netdev - Re: [PATCH bpf-next v3 5/6] selftests/bpf: Test bpf_xdp_pull

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Message-ID: <28df67a9-528d-41e9-8441-722237b9add9@linux.dev>
Date: Wed, 17 Sep 2025 10:54:46 -0700
From: Martin KaFai Lau <martin.lau@...ux.dev>
To: Amery Hung <ameryhung@...il.com>
Cc: bpf@...r.kernel.org, netdev@...r.kernel.org,
 alexei.starovoitov@...il.com, andrii@...nel.org, daniel@...earbox.net,
 paul.chaignon@...il.com, kuba@...nel.org, stfomichev@...il.com,
 martin.lau@...nel.org, mohsin.bashr@...il.com, noren@...dia.com,
 dtatulea@...dia.com, saeedm@...dia.com, tariqt@...dia.com,
 mbloch@...dia.com, maciej.fijalkowski@...el.com, kernel-team@...a.com
Subject: Re: [PATCH bpf-next v3 5/6] selftests/bpf: Test bpf_xdp_pull_data

On 9/15/25 3:48 PM, Amery Hung wrote:
> +/* Find sizes of struct skb_shared_info and struct xdp_frame so that
> + * we can calculate the maximum pull lengths for test cases
> + */
> +int find_xdp_sizes(struct test_xdp_pull_data *skel, int frame_sz)

static

> +{
> +	LIBBPF_OPTS(bpf_test_run_opts, topts);
> +	struct xdp_md ctx = {};
> +	int prog_fd, err;
> +	__u8 *buf;
> +
> +	buf = calloc(frame_sz, sizeof(__u8));

buf is leaked.

> +	if (!ASSERT_OK_PTR(buf, "calloc buf"))
> +		return -ENOMEM;
> +
> +	topts.data_in = buf;
> +	topts.data_out = buf;
> +	topts.data_size_in = frame_sz;
> +	topts.data_size_out = frame_sz;
> +	/* Pass a data_end larger than the linear space available to make sure
> +	 * bpf_prog_test_run_xdp() will fill the linear data area so that
> +	 * xdp_find_data_hard_end can infer the size of struct skb_shared_info
> +	 */
> +	ctx.data_end = frame_sz;
> +	topts.ctx_in = &ctx;
> +	topts.ctx_out = &ctx;
> +	topts.ctx_size_in = sizeof(ctx);
> +	topts.ctx_size_out = sizeof(ctx);
> +
> +	prog_fd = bpf_program__fd(skel->progs.xdp_find_sizes);
> +	err = bpf_prog_test_run_opts(prog_fd, &topts);
> +	ASSERT_OK(err, "bpf_prog_test_run_opts");
> +
> +	return err;
> +}
> +
> +/* xdp_pull_data_prog will directly read a marker 0xbb stored at buf[1024]
> + * so caller expecting XDP_PASS should always pass pull_len no less than 1024
> + */
> +void run_test(struct test_xdp_pull_data *skel, int retval,

static