netdev - [PATCH net-next] net: usb: sr9700: stop lying about skb->truesize

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Message-ID: <20240506143939.3673865-1-edumazet@google.com>
Date: Mon,  6 May 2024 14:39:39 +0000
From: Eric Dumazet <edumazet@...gle.com>
To: "David S . Miller" <davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org>, 
	Paolo Abeni <pabeni@...hat.com>
Cc: netdev@...r.kernel.org, eric.dumazet@...il.com, 
	Eric Dumazet <edumazet@...gle.com>
Subject: [PATCH net-next] net: usb: sr9700: stop lying about skb->truesize

Some usb drivers set small skb->truesize and break
core networking stacks.

In this patch, I removed one of the skb->truesize override.

I also replaced one skb_clone() by an allocation of a fresh
and small skb, to get minimally sized skbs, like we did
in commit 1e2c61172342 ("net: cdc_ncm: reduce skb truesize
in rx path") and 4ce62d5b2f7a ("net: usb: ax88179_178a:
stop lying about skb->truesize")

Fixes: c9b37458e956 ("USB2NET : SR9700 : One chip USB 1.1 USB2NET SR9700Device Driver Support")
Signed-off-by: Eric Dumazet <edumazet@...gle.com>
---
 drivers/net/usb/sr9700.c | 10 +++-------
 1 file changed, 3 insertions(+), 7 deletions(-)

diff --git a/drivers/net/usb/sr9700.c b/drivers/net/usb/sr9700.c
index 3164451e1010cc80a67e2fddc89a9e59a6721cab..0a662e42ed96593cf20d4209af2bc64a74f307df 100644
--- a/drivers/net/usb/sr9700.c
+++ b/drivers/net/usb/sr9700.c
@@ -421,19 +421,15 @@ static int sr9700_rx_fixup(struct usbnet *dev, struct sk_buff *skb)
 			skb_pull(skb, 3);
 			skb->len = len;
 			skb_set_tail_pointer(skb, len);
-			skb->truesize = len + sizeof(struct sk_buff);
 			return 2;
 		}
 
-		/* skb_clone is used for address align */
-		sr_skb = skb_clone(skb, GFP_ATOMIC);
+		sr_skb = netdev_alloc_skb_ip_align(dev->net, len);
 		if (!sr_skb)
 			return 0;
 
-		sr_skb->len = len;
-		sr_skb->data = skb->data + 3;
-		skb_set_tail_pointer(sr_skb, len);
-		sr_skb->truesize = len + sizeof(struct sk_buff);
+		skb_put(sr_skb, len);
+		memcpy(sr_skb->data, skb->data + 3, len);
 		usbnet_skb_return(dev, sr_skb);
 
 		skb_pull(skb, len + SR_RX_OVERHEAD);
-- 
2.45.0.rc1.225.g2a3ae87e7f-goog