Subject: [PATCH] net: helper function for skb_shift

From: Richard Gobert <[email-masked]>
Date: Thu, 16 Jun 2022 14:26:29 +0200

Move the len fields manipulation in the skbs to a helper function.
There is a comment specifically requesting this. This improves the
readability of skb_shift.

Signed-off-by: Richard Gobert <[email-masked]>
---
 net/core/skbuff.c | 22 ++++++++++++++--------
 1 file changed, 14 insertions(+), 8 deletions(-)

diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 30b523fa4ad2..8a0a941915e8 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -3508,6 +3508,19 @@ static int skb_prepare_for_shift(struct sk_buff *skb)
 }
 
 /**
+ * skb_shift_len - Update length fields of skbs when shifting.
+ */
+static inline void skb_shift_len(struct sk_buff *tgt, struct sk_buff *skb, int shiftlen)
+{
+	skb->len -= shiftlen;
+	skb->data_len -= shiftlen;
+	skb->truesize -= shiftlen;
+	tgt->len += shiftlen;
+	tgt->data_len += shiftlen;
+	tgt->truesize += shiftlen;
+}
+
+/**
  * skb_shift - Shifts paged data partially from skb to another
  * @tgt: buffer into which tail data gets added
  * @skb: buffer from which the paged data comes from
@@ -3634,14 +3647,7 @@ int skb_shift(struct sk_buff *tgt, struct sk_buff *skb, int shiftlen)
 	tgt->ip_summed = CHECKSUM_PARTIAL;
 	skb->ip_summed = CHECKSUM_PARTIAL;
 
-	/* Yak, is it really working this way? Some helper please? */
-	skb->len -= shiftlen;
-	skb->data_len -= shiftlen;
-	skb->truesize -= shiftlen;
-	tgt->len += shiftlen;
-	tgt->data_len += shiftlen;
-	tgt->truesize += shiftlen;
-
+	skb_shift_len(tgt, skb, shiftlen);
 	return shiftlen;
 }
 
-- 
2.36.1