netdev - [PATCH net-next V3 2/9] eth: fbnic: Update Headroom

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Message-ID: <20250812220150.161848-3-mohsin.bashr@gmail.com>
Date: Tue, 12 Aug 2025 15:01:43 -0700
From: Mohsin Bashir <mohsin.bashr@...il.com>
To: netdev@...r.kernel.org
Cc: aleksander.lobakin@...el.com,
	alexanderduyck@...com,
	andrew+netdev@...n.ch,
	ast@...nel.org,
	bpf@...r.kernel.org,
	corbet@....net,
	daniel@...earbox.net,
	davem@...emloft.net,
	edumazet@...gle.com,
	hawk@...nel.org,
	horms@...nel.org,
	john.fastabend@...il.com,
	kernel-team@...a.com,
	kuba@...nel.org,
	linux-doc@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	mohsin.bashr@...il.com,
	pabeni@...hat.com,
	sdf@...ichev.me,
	vadim.fedorenko@...ux.dev
Subject: [PATCH net-next V3 2/9] eth: fbnic: Update Headroom

Fbnic currently reserves a minimum of 64B headroom, but this is
insufficient for inserting additional headers (e.g., IPV6) via XDP, as
only 24 bytes are available for adjustment. To address this limitation,
increase the headroom to a larger value while ensuring better page use.
Although the resulting headroom (192B) is smaller than the recommended
value (256B), forcing the headroom to 256B would require aligning to
256B (as opposed to the current 128B), which can push the max headroom
to 511B.

Signed-off-by: Jakub Kicinski <kuba@...nel.org>
Signed-off-by: Mohsin Bashir <mohsin.bashr@...il.com>
---
 drivers/net/ethernet/meta/fbnic/fbnic_txrx.h | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/meta/fbnic/fbnic_txrx.h b/drivers/net/ethernet/meta/fbnic/fbnic_txrx.h
index 7d27712d5462..66c84375e299 100644
--- a/drivers/net/ethernet/meta/fbnic/fbnic_txrx.h
+++ b/drivers/net/ethernet/meta/fbnic/fbnic_txrx.h
@@ -50,8 +50,9 @@ struct fbnic_net;
 
 #define FBNIC_RX_TROOM \
 	SKB_DATA_ALIGN(sizeof(struct skb_shared_info))
+#define FBNIC_RX_HROOM_PAD		128
 #define FBNIC_RX_HROOM \
-	(ALIGN(FBNIC_RX_TROOM + NET_SKB_PAD, 128) - FBNIC_RX_TROOM)
+	(ALIGN(FBNIC_RX_TROOM + FBNIC_RX_HROOM_PAD, 128) - FBNIC_RX_TROOM)
 #define FBNIC_RX_PAD			0
 #define FBNIC_RX_PAYLD_OFFSET		0
 #define FBNIC_RX_PAYLD_PG_CL		0
-- 
2.47.3