From: Tariq Toukan <tariqt@nvidia.com>
Date: Sun, 17 Jan 2021 16:59:43 +0200
Subject: net/bonding: Take IP hash logic into a helper
Patch-mainline: v5.12-rc1
Git-commit: 5b99854540e35c2c6a226bcdb4bafbae1bccad5a
References: bsc#1181719

Hash logic on L3 will be used in a downstream patch for one more use
case.
Take it to a function for a better code reuse.

Signed-off-by: Tariq Toukan <tariqt@nvidia.com>
Reviewed-by: Boris Pismenny <borisp@nvidia.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Acked-by: Michal Kubecek <mkubecek@suse.cz>

---
 drivers/net/bonding/bond_main.c | 16 +++++++++++-----
 1 file changed, 11 insertions(+), 5 deletions(-)

--- a/drivers/net/bonding/bond_main.c
+++ b/drivers/net/bonding/bond_main.c
@@ -3540,6 +3540,16 @@ static bool bond_flow_dissect(struct bonding *bond, struct sk_buff *skb,
 	return true;
 }
 
+static u32 bond_ip_hash(u32 hash, struct flow_keys *flow)
+{
+	hash ^= (__force u32)flow_get_u32_dst(flow) ^
+		(__force u32)flow_get_u32_src(flow);
+	hash ^= (hash >> 16);
+	hash ^= (hash >> 8);
+	/* discard lowest hash bit to deal with the common even ports pattern */
+	return hash >> 1;
+}
+
 /**
  * bond_xmit_hash - generate a hash value based on the xmit policy
  * @bond: bonding device
@@ -3570,12 +3580,8 @@ u32 bond_xmit_hash(struct bonding *bond, struct sk_buff *skb)
 		else
 			memcpy(&hash, &flow.ports.ports, sizeof(hash));
 	}
-	hash ^= (__force u32)flow_get_u32_dst(&flow) ^
-		(__force u32)flow_get_u32_src(&flow);
-	hash ^= (hash >> 16);
-	hash ^= (hash >> 8);
 
-	return hash >> 1;
+	return bond_ip_hash(hash, &flow);
 }
 
 /*-------------------------- Device entry points ----------------------------*/