From: Davide Caratti <dcaratti@redhat.com>
Date: Thu, 18 May 2017 15:44:39 +0200
Subject: sk_buff: remove support for csum_bad in sk_buff
Patch-mainline: v4.13-rc1
Git-commit: 219f1d79871257e9603f504dce0fe8ebf47aad08
References: bsc#1056787

This bit was introduced with commit 5a21232983aa ("net: Support for
csum_bad in skbuff") to reduce the stack workload when processing RX
packets carrying a wrong Internet Checksum. Up to now, only one driver and
GRO core are setting it.

Suggested-by: Tom Herbert <tom@herbertland.com>
Signed-off-by: Davide Caratti <dcaratti@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 drivers/net/ethernet/aquantia/atlantic/aq_ring.c |    2 +-
 include/linux/netdevice.h                        |    4 +---
 include/linux/skbuff.h                           |   23 ++---------------------
 net/bridge/netfilter/nft_reject_bridge.c         |    5 +----
 net/core/dev.c                                   |    3 ---
 net/ipv4/netfilter/nf_reject_ipv4.c              |    2 +-
 net/ipv6/netfilter/nf_reject_ipv6.c              |    3 ---
 7 files changed, 6 insertions(+), 36 deletions(-)

--- a/drivers/net/ethernet/aquantia/atlantic/aq_ring.c
+++ b/drivers/net/ethernet/aquantia/atlantic/aq_ring.c
@@ -223,7 +223,7 @@ int aq_ring_rx_clean(struct aq_ring_s *s
 		skb->protocol = eth_type_trans(skb, ndev);
 		if (unlikely(buff->is_cso_err)) {
 			++self->stats.rx.errors;
-			__skb_mark_checksum_bad(skb);
+			skb->ip_summed = CHECKSUM_NONE;
 		} else {
 			if (buff->is_ip_cso) {
 				__skb_incr_checksum_unnecessary(skb);
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -2574,9 +2574,7 @@ static inline void skb_gro_incr_csum_unn
 	if (__skb_gro_checksum_validate_needed(skb, zero_okay, check))	\
 		__ret = __skb_gro_checksum_validate_complete(skb,	\
 				compute_pseudo(skb, proto));		\
-	if (__ret)							\
-		__skb_mark_checksum_bad(skb);				\
-	else								\
+	if (!__ret)							\
 		skb_gro_incr_csum_unnecessary(skb);			\
 	__ret;								\
 })
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -745,7 +745,7 @@ struct sk_buff {
 	__u8			csum_valid:1;
 	__u8			csum_complete_sw:1;
 	__u8			csum_level:2;
-	__u8			csum_bad:1;
+	__u8			__csum_bad_unused:1; /* one bit hole */
 
 	__u8			dst_pending_confirm:1;
 #ifdef CONFIG_IPV6_NDISC_NODETYPE
@@ -3396,21 +3396,6 @@ static inline void __skb_incr_checksum_u
 	}
 }
 
-static inline void __skb_mark_checksum_bad(struct sk_buff *skb)
-{
-	/* Mark current checksum as bad (typically called from GRO
-	 * path). In the case that ip_summed is CHECKSUM_NONE
-	 * this must be the first checksum encountered in the packet.
-	 * When ip_summed is CHECKSUM_UNNECESSARY, this is the first
-	 * checksum after the last one validated. For UDP, a zero
-	 * checksum can not be marked as bad.
-	 */
-
-	if (skb->ip_summed == CHECKSUM_NONE ||
-	    skb->ip_summed == CHECKSUM_UNNECESSARY)
-		skb->csum_bad = 1;
-}
-
 /* Check if we need to perform checksum complete validation.
  *
  * Returns true if checksum complete is needed, false otherwise
@@ -3464,9 +3449,6 @@ static inline __sum16 __skb_checksum_val
 			skb->csum_valid = 1;
 			return 0;
 		}
-	} else if (skb->csum_bad) {
-		/* ip_summed == CHECKSUM_NONE in this case */
-		return (__force __sum16)1;
 	}
 
 	skb->csum = psum;
@@ -3526,8 +3508,7 @@ static inline __wsum null_compute_pseudo
 
 static inline bool __skb_checksum_convert_check(struct sk_buff *skb)
 {
-	return (skb->ip_summed == CHECKSUM_NONE &&
-		skb->csum_valid && !skb->csum_bad);
+	return (skb->ip_summed == CHECKSUM_NONE && skb->csum_valid);
 }
 
 static inline void __skb_checksum_convert(struct sk_buff *skb,
--- a/net/bridge/netfilter/nft_reject_bridge.c
+++ b/net/bridge/netfilter/nft_reject_bridge.c
@@ -111,7 +111,7 @@ static void nft_reject_br_send_v4_unreac
 	__wsum csum;
 	u8 proto;
 
-	if (oldskb->csum_bad || !nft_bridge_iphdr_validate(oldskb))
+	if (!nft_bridge_iphdr_validate(oldskb))
 		return;
 
 	/* IP header checks: fragment. */
@@ -226,9 +226,6 @@ static bool reject6_br_csum_ok(struct sk
 	__be16 fo;
 	u8 proto = ip6h->nexthdr;
 
-	if (skb->csum_bad)
-		return false;
-
 	if (skb_csum_unnecessary(skb))
 		return true;
 
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -4679,9 +4679,6 @@ static enum gro_result dev_gro_receive(s
 	if (netif_elide_gro(skb->dev))
 		goto normal;
 
-	if (skb->csum_bad)
-		goto normal;
-
 	gro_list_prepare(napi, skb);
 
 	rcu_read_lock();
--- a/net/ipv4/netfilter/nf_reject_ipv4.c
+++ b/net/ipv4/netfilter/nf_reject_ipv4.c
@@ -172,7 +172,7 @@ void nf_send_unreach(struct sk_buff *skb
 	struct iphdr *iph = ip_hdr(skb_in);
 	u8 proto;
 
-	if (skb_in->csum_bad || iph->frag_off & htons(IP_OFFSET))
+	if (iph->frag_off & htons(IP_OFFSET))
 		return;
 
 	if (skb_csum_unnecessary(skb_in)) {
--- a/net/ipv6/netfilter/nf_reject_ipv6.c
+++ b/net/ipv6/netfilter/nf_reject_ipv6.c
@@ -220,9 +220,6 @@ static bool reject6_csum_ok(struct sk_bu
 	__be16 fo;
 	u8 proto;
 
-	if (skb->csum_bad)
-		return false;
-
 	if (skb_csum_unnecessary(skb))
 		return true;