From: Li RongQing <lirongqing@baidu.com>
Date: Fri, 3 Aug 2018 15:50:02 +0800
Subject: tun: not use hardcoded mask value
Patch-mainline: v4.19-rc1
Git-commit: f13b546847ff5862ea313f3e79010c52c3fe32b4
References: bsc#1109837

0x3ff in tun_hashfn is mask of TUN_NUM_FLOW_ENTRIES, instead
of hardcode, define a macro to setup the relationship with
TUN_NUM_FLOW_ENTRIES

Signed-off-by: Li RongQing <lirongqing@baidu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 drivers/net/tun.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -199,6 +199,7 @@ struct tun_flow_entry {
 };
 
 #define TUN_NUM_FLOW_ENTRIES 1024
+#define TUN_MASK_FLOW_ENTRIES (TUN_NUM_FLOW_ENTRIES - 1)
 
 struct tun_prog {
 	struct rcu_head rcu;
@@ -405,7 +406,7 @@ static inline __virtio16 cpu_to_tun16(st
 
 static inline u32 tun_hashfn(u32 rxhash)
 {
-	return rxhash & 0x3ff;
+	return rxhash & TUN_MASK_FLOW_ENTRIES;
 }
 
 static struct tun_flow_entry *tun_flow_find(struct hlist_head *head, u32 rxhash)