netdev - [PATCH bpf-next v7 5/8] bpf: Make variables in bpf_prog_test_run

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Message-ID: <20250922233356.3356453-6-ameryhung@gmail.com>
Date: Mon, 22 Sep 2025 16:33:53 -0700
From: Amery Hung <ameryhung@...il.com>
To: bpf@...r.kernel.org
Cc: 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: [PATCH bpf-next v7 5/8] bpf: Make variables in bpf_prog_test_run_xdp less confusing

Change the variable naming in bpf_prog_test_run_xdp() to make the
overall logic less confusing. As different modes were added to the
function over the time, some variables got overloaded, making
it hard to understand and changing the code becomes error-prone.

Replace "size" with "linear_sz" where it refers to the size of metadata
and data. If "size" refers to input data size, use test.data_size_in
directly.

Replace "max_data_sz" with "max_linear_sz" to better reflect the fact
that it is the maximum size of metadata and data (i.e., linear_sz). Also,
xdp_rxq.frags_size is always PAGE_SIZE, so just set it directly instead
of subtracting headroom and tailroom and adding them back.

Signed-off-by: Amery Hung <ameryhung@...il.com>
---
 net/bpf/test_run.c | 26 +++++++++++++-------------
 1 file changed, 13 insertions(+), 13 deletions(-)

diff --git a/net/bpf/test_run.c b/net/bpf/test_run.c
index 4a862d605386..2a0af50f177e 100644
--- a/net/bpf/test_run.c
+++ b/net/bpf/test_run.c
@@ -1207,9 +1207,9 @@ int bpf_prog_test_run_xdp(struct bpf_prog *prog, const union bpf_attr *kattr,
 {
 	bool do_live = (kattr->test.flags & BPF_F_TEST_XDP_LIVE_FRAMES);
 	u32 tailroom = SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
+	u32 retval = 0, duration, max_linear_sz, size;
+	u32 linear_sz = kattr->test.data_size_in;
 	u32 batch_size = kattr->test.batch_size;
-	u32 retval = 0, duration, max_data_sz;
-	u32 size = kattr->test.data_size_in;
 	u32 headroom = XDP_PACKET_HEADROOM;
 	u32 repeat = kattr->test.repeat;
 	struct netdev_rx_queue *rxqueue;
@@ -1246,7 +1246,7 @@ int bpf_prog_test_run_xdp(struct bpf_prog *prog, const union bpf_attr *kattr,
 
 	if (ctx) {
 		/* There can't be user provided data before the meta data */
-		if (ctx->data_meta || ctx->data_end != size ||
+		if (ctx->data_meta || ctx->data_end != kattr->test.data_size_in ||
 		    ctx->data > ctx->data_end ||
 		    unlikely(xdp_metalen_invalid(ctx->data)) ||
 		    (do_live && (kattr->test.data_out || kattr->test.ctx_out)))
@@ -1255,30 +1255,30 @@ int bpf_prog_test_run_xdp(struct bpf_prog *prog, const union bpf_attr *kattr,
 		headroom -= ctx->data;
 	}
 
-	max_data_sz = PAGE_SIZE - headroom - tailroom;
-	if (size > max_data_sz) {
-		/* disallow live data mode for jumbo frames */
-		if (do_live)
-			goto free_ctx;
-		size = max_data_sz;
-	}
+	max_linear_sz = PAGE_SIZE - headroom - tailroom;
+	linear_sz = min_t(u32, linear_sz, max_linear_sz);
+
+	/* disallow live data mode for jumbo frames */
+	if (do_live && kattr->test.data_size_in > linear_sz)
+		goto free_ctx;
 
-	data = bpf_test_init(kattr, size, max_data_sz, headroom, tailroom);
+	data = bpf_test_init(kattr, linear_sz, max_linear_sz, headroom, tailroom);
 	if (IS_ERR(data)) {
 		ret = PTR_ERR(data);
 		goto free_ctx;
 	}
 
 	rxqueue = __netif_get_rx_queue(current->nsproxy->net_ns->loopback_dev, 0);
-	rxqueue->xdp_rxq.frag_size = headroom + max_data_sz + tailroom;
+	rxqueue->xdp_rxq.frag_size = PAGE_SIZE;
 	xdp_init_buff(&xdp, rxqueue->xdp_rxq.frag_size, &rxqueue->xdp_rxq);
-	xdp_prepare_buff(&xdp, data, headroom, size, true);
+	xdp_prepare_buff(&xdp, data, headroom, linear_sz, true);
 	sinfo = xdp_get_shared_info_from_buff(&xdp);
 
 	ret = xdp_convert_md_to_buff(ctx, &xdp);
 	if (ret)
 		goto free_data;
 
+	size = linear_sz;
 	if (unlikely(kattr->test.data_size_in > size)) {
 		void __user *data_in = u64_to_user_ptr(kattr->test.data_in);
 
-- 
2.47.3