netdev - [PATCH net-next v2 1/2] net: ip: refactor SG checks

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Date:   Tue, 22 Jun 2021 15:50:56 -0700
From:   Jakub Kicinski <kuba@...nel.org>
To:     davem@...emloft.net
Cc:     netdev@...r.kernel.org, willemb@...gle.com, eric.dumazet@...il.com,
        dsahern@...il.com, yoshfuji@...ux-ipv6.org,
        Jakub Kicinski <kuba@...nel.org>
Subject: [PATCH net-next v2 1/2] net: ip: refactor SG checks

There is a number of rt->dst.dev->features & NETIF_F_SG checks
scattered throughout the code. Shorten the lines by caching
the result of this check.

Signed-off-by: Jakub Kicinski <kuba@...nel.org>
---
 net/ipv4/ip_output.c  | 13 ++++++-------
 net/ipv6/ip6_output.c | 13 ++++++-------
 2 files changed, 12 insertions(+), 14 deletions(-)

diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c
index c3efc7d658f6..90031f5446bd 100644
--- a/net/ipv4/ip_output.c
+++ b/net/ipv4/ip_output.c
@@ -981,12 +981,14 @@ static int __ip_append_data(struct sock *sk,
 	unsigned int maxfraglen, fragheaderlen, maxnonfragsize;
 	int csummode = CHECKSUM_NONE;
 	struct rtable *rt = (struct rtable *)cork->dst;
+	bool has_sg, paged, extra_uref = false;
 	unsigned int wmem_alloc_delta = 0;
-	bool paged, extra_uref = false;
 	u32 tskey = 0;
 
 	skb = skb_peek_tail(queue);
 
+	has_sg = rt->dst.dev->features & NETIF_F_SG;
+
 	exthdrlen = !skb ? rt->dst.header_len : 0;
 	mtu = cork->gso_size ? IP_MAX_MTU : cork->fragsize;
 	paged = !!cork->gso_size;
@@ -1023,8 +1025,7 @@ static int __ip_append_data(struct sock *sk,
 		if (!uarg)
 			return -ENOBUFS;
 		extra_uref = !skb_zcopy(skb);	/* only ref on new uarg */
-		if (rt->dst.dev->features & NETIF_F_SG &&
-		    csummode == CHECKSUM_PARTIAL) {
+		if (has_sg && csummode == CHECKSUM_PARTIAL) {
 			paged = true;
 		} else {
 			uarg->zerocopy = 0;
@@ -1074,8 +1075,7 @@ static int __ip_append_data(struct sock *sk,
 			fraglen = datalen + fragheaderlen;
 			pagedlen = 0;
 
-			if ((flags & MSG_MORE) &&
-			    !(rt->dst.dev->features&NETIF_F_SG))
+			if ((flags & MSG_MORE) && !has_sg)
 				alloclen = mtu;
 			else if (!paged)
 				alloclen = fraglen;
@@ -1174,8 +1174,7 @@ static int __ip_append_data(struct sock *sk,
 		if (copy > length)
 			copy = length;
 
-		if (!(rt->dst.dev->features&NETIF_F_SG) &&
-		    skb_tailroom(skb) >= copy) {
+		if (!has_sg && skb_tailroom(skb) >= copy) {
 			unsigned int off;
 
 			off = skb->len;
diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
index ff4f9ebcf7f6..c667b7e2856f 100644
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -1444,8 +1444,8 @@ static int __ip6_append_data(struct sock *sk,
 	struct ipv6_txoptions *opt = v6_cork->opt;
 	int csummode = CHECKSUM_NONE;
 	unsigned int maxnonfragsize, headersize;
+	bool has_sg, paged, extra_uref = false;
 	unsigned int wmem_alloc_delta = 0;
-	bool paged, extra_uref = false;
 
 	skb = skb_peek_tail(queue);
 	if (!skb) {
@@ -1453,6 +1453,8 @@ static int __ip6_append_data(struct sock *sk,
 		dst_exthdrlen = rt->dst.header_len - rt->rt6i_nfheader_len;
 	}
 
+	has_sg = rt->dst.dev->features & NETIF_F_SG;
+
 	paged = !!cork->gso_size;
 	mtu = cork->gso_size ? IP6_MAX_MTU : cork->fragsize;
 	orig_mtu = mtu;
@@ -1515,8 +1517,7 @@ static int __ip6_append_data(struct sock *sk,
 		if (!uarg)
 			return -ENOBUFS;
 		extra_uref = !skb_zcopy(skb);	/* only ref on new uarg */
-		if (rt->dst.dev->features & NETIF_F_SG &&
-		    csummode == CHECKSUM_PARTIAL) {
+		if (has_sg && csummode == CHECKSUM_PARTIAL) {
 			paged = true;
 		} else {
 			uarg->zerocopy = 0;
@@ -1582,8 +1583,7 @@ static int __ip6_append_data(struct sock *sk,
 			fraglen = datalen + fragheaderlen;
 			pagedlen = 0;
 
-			if ((flags & MSG_MORE) &&
-			    !(rt->dst.dev->features&NETIF_F_SG))
+			if ((flags & MSG_MORE) && !has_sg)
 				alloclen = mtu;
 			else if (!paged)
 				alloclen = fraglen;
@@ -1698,8 +1698,7 @@ static int __ip6_append_data(struct sock *sk,
 		if (copy > length)
 			copy = length;
 
-		if (!(rt->dst.dev->features&NETIF_F_SG) &&
-		    skb_tailroom(skb) >= copy) {
+		if (!has_sg && skb_tailroom(skb) >= copy) {
 			unsigned int off;
 
 			off = skb->len;
-- 
2.31.1