openwrt/target/linux/generic/backport-4.9/023-6-ch9200-use-skb_cow_he...

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From 6bc6895bdd6744e0136eaa4a11fbdb20a7db4e40 Mon Sep 17 00:00:00 2001
From: Eric Dumazet <edumazet@google.com>
Date: Wed, 19 Apr 2017 09:59:25 -0700
Subject: [PATCH] ch9200: use skb_cow_head() to deal with cloned skbs
We need to ensure there is enough headroom to push extra header,
but we also need to check if we are allowed to change headers.
skb_cow_head() is the proper helper to deal with this.
Fixes: 4a476bd6d1d9 ("usbnet: New driver for QinHeng CH9200 devices")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: James Hughes <james.hughes@raspberrypi.org>
Cc: Matthew Garrett <mjg59@srcf.ucam.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
drivers/net/usb/ch9200.c | 9 ++-------
1 file changed, 2 insertions(+), 7 deletions(-)
--- a/drivers/net/usb/ch9200.c
+++ b/drivers/net/usb/ch9200.c
@@ -254,14 +254,9 @@ static struct sk_buff *ch9200_tx_fixup(s
tx_overhead = 0x40;
len = skb->len;
- if (skb_headroom(skb) < tx_overhead) {
- struct sk_buff *skb2;
-
- skb2 = skb_copy_expand(skb, tx_overhead, 0, flags);
+ if (skb_cow_head(skb, tx_overhead)) {
dev_kfree_skb_any(skb);
- skb = skb2;
- if (!skb)
- return NULL;
+ return NULL;
}
__skb_push(skb, tx_overhead);