netdev - [PATCH v3] net: helper function skb_len

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Date:   Wed, 22 Jun 2022 18:09:03 +0200
From:   Richard Gobert <richardbgobert@...il.com>
To:     davem@...emloft.net, kuba@...nel.org, pabeni@...hat.com,
        steffen.klassert@...unet.com, herbert@...dor.apana.org.au,
        yoshfuji@...ux-ipv6.org, dsahern@...nel.org, edumazet@...gle.com,
        willemb@...gle.com, imagedong@...cent.com, talalahmad@...gle.com,
        kafai@...com, vasily.averin@...ux.dev, luiz.von.dentz@...el.com,
        jk@...econstruct.com.au, netdev@...r.kernel.org
Subject: [PATCH v3] net: helper function skb_len_add

Move the len fields manipulation in the skbs to a helper function.
There is a comment specifically requesting this and there are several
other areas in the code displaying the same pattern which can be
refactored.
This improves code readability.

Signed-off-by: Richard Gobert <richardbgobert@...il.com>
---
 include/linux/skbuff.h | 12 ++++++++++++
 include/net/sock.h     |  4 +---
 net/core/skbuff.c      | 13 +++----------
 net/ipv4/esp4.c        |  4 +---
 net/ipv4/ip_output.c   |  8 ++------
 5 files changed, 19 insertions(+), 22 deletions(-)

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 84d78df60453..b02e0a314683 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -2417,6 +2417,18 @@ static inline unsigned int skb_pagelen(const struct sk_buff *skb)
 }
 
 /**
+ * skb_len_add - adds a number to len fields of skb
+ * @skb: buffer to add len to
+ * @delta: number of bytes to add
+ */
+static inline void skb_len_add(struct sk_buff *skb, int delta)
+{
+	skb->len += delta;
+	skb->data_len += delta;
+	skb->truesize += delta;
+}
+
+/**
  * __skb_fill_page_desc - initialise a paged fragment in an skb
  * @skb: buffer containing fragment to be initialised
  * @i: paged fragment index to initialise
diff --git a/include/net/sock.h b/include/net/sock.h
index a01d6c421aa2..648658f782c2 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -2230,9 +2230,7 @@ static inline int skb_copy_to_page_nocache(struct sock *sk, struct iov_iter *fro
 	if (err)
 		return err;
 
-	skb->len	     += copy;
-	skb->data_len	     += copy;
-	skb->truesize	     += copy;
+	skb_len_add(skb, copy);
 	sk_wmem_queued_add(sk, copy);
 	sk_mem_charge(sk, copy);
 	return 0;
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 30b523fa4ad2..2110db41cb41 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -3195,9 +3195,7 @@ skb_zerocopy(struct sk_buff *to, struct sk_buff *from, int len, int hlen)
 		}
 	}
 
-	to->truesize += len + plen;
-	to->len += len + plen;
-	to->data_len += len + plen;
+	skb_len_add(to, len + plen);
 
 	if (unlikely(skb_orphan_frags(from, GFP_ATOMIC))) {
 		skb_tx_error(from);
@@ -3634,13 +3632,8 @@ 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_len_add(skb, -shiftlen);
+	skb_len_add(tgt, shiftlen);
 
 	return shiftlen;
 }
diff --git a/net/ipv4/esp4.c b/net/ipv4/esp4.c
index d747166bb291..2ad3d6955dae 100644
--- a/net/ipv4/esp4.c
+++ b/net/ipv4/esp4.c
@@ -502,9 +502,7 @@ int esp_output_head(struct xfrm_state *x, struct sk_buff *skb, struct esp_info *
 
 			nfrags++;
 
-			skb->len += tailen;
-			skb->data_len += tailen;
-			skb->truesize += tailen;
+			skb_len_add(skb, tailen);
 			if (sk && sk_fullsock(sk))
 				refcount_add(tailen, &sk->sk_wmem_alloc);
 
diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c
index 00b4bf26fd93..5e32a2f86fbd 100644
--- a/net/ipv4/ip_output.c
+++ b/net/ipv4/ip_output.c
@@ -1214,9 +1214,7 @@ static int __ip_append_data(struct sock *sk,
 
 			pfrag->offset += copy;
 			skb_frag_size_add(&skb_shinfo(skb)->frags[i - 1], copy);
-			skb->len += copy;
-			skb->data_len += copy;
-			skb->truesize += copy;
+			skb_len_add(skb, copy);
 			wmem_alloc_delta += copy;
 		} else {
 			err = skb_zerocopy_iter_dgram(skb, from, copy);
@@ -1443,9 +1441,7 @@ ssize_t	ip_append_page(struct sock *sk, struct flowi4 *fl4, struct page *page,
 			skb->csum = csum_block_add(skb->csum, csum, skb->len);
 		}
 
-		skb->len += len;
-		skb->data_len += len;
-		skb->truesize += len;
+		skb_len_add(skb, len);
 		refcount_add(len, &sk->sk_wmem_alloc);
 		offset += len;
 		size -= len;
-- 
2.36.1