Commit 50988747 authored by Oleksij Rempel's avatar Oleksij Rempel Committed by Jakub Kicinski
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net: usb: lan78xx: fix TX byte statistics for small packets 



Account for hardware auto-padding in TX byte counters to reflect actual
wire traffic.

The LAN7850 hardware automatically pads undersized frames to the minimum
Ethernet frame length (ETH_ZLEN, 60 bytes). However, the driver tracks
the network statistics based on the unpadded socket buffer length. This
results in the tx_bytes counter under-reporting the actual physical
bytes placed on the Ethernet wire for small packets (like short ARP or
ICMP requests).

Use max_t() to ensure the transmission statistics accurately account for
the hardware-generated padding.

Fixes: d383216a ("lan78xx: Introduce Tx URB processing improvements")
Cc: stable@vger.kernel.org
Signed-off-by: default avatarOleksij Rempel <o.rempel@pengutronix.de>
Link: https://patch.msgid.link/20260305143429.530909-3-o.rempel@pengutronix.de


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent e4f774a0

drivers/net/usb/lan78xx.c

+1 −1
Original line number Diff line number Diff line
@@ -4178,7 +4178,7 @@ static struct skb_data *lan78xx_tx_buf_fill(struct lan78xx_net *dev, 
		}



		tx_data += len;

		entry->length += len;

		entry->length += max_t(unsigned int, len, ETH_ZLEN);

		entry->num_of_packet += skb_shinfo(skb)->gso_segs ?: 1;



		dev_kfree_skb_any(skb);