[PATCH][net-next] net/ipv6: compute anycast address hash only if dev is null

[PATCH][net-next] net/ipv6: compute anycast address hash only if dev is null

[Li RongQing]

avoid to compute the hash value if dev is not null, since
hash value is not used

Signed-off-by: Li RongQing <lirongqing@baidu.com>
---
 net/ipv6/anycast.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/net/ipv6/anycast.c b/net/ipv6/anycast.c
index 94999058e110..a20e344486cb 100644
--- a/net/ipv6/anycast.c
+++ b/net/ipv6/anycast.c
@@ -433,15 +433,16 @@ static bool ipv6_chk_acast_dev(struct net_device *dev, const struct in6_addr *ad
 bool ipv6_chk_acast_addr(struct net *net, struct net_device *dev,
 			 const struct in6_addr *addr)
 {
-	unsigned int hash = inet6_acaddr_hash(net, addr);
 	struct net_device *nh_dev;
 	struct ifacaddr6 *aca;
 	bool found = false;
+	unsigned int hash;
 
 	rcu_read_lock();
 	if (dev)
 		found = ipv6_chk_acast_dev(dev, addr);
-	else
+	else {
+		hash = inet6_acaddr_hash(net, addr);
 		hlist_for_each_entry_rcu(aca, &inet6_acaddr_lst[hash],
 					 aca_addr_lst) {
 			nh_dev = fib6_info_nh_dev(aca->aca_rt);
@@ -452,6 +453,7 @@ bool ipv6_chk_acast_addr(struct net *net, struct net_device *dev,
 				break;
 			}
 		}
+	}
 	rcu_read_unlock();
 	return found;
 }
-- 
2.16.2

Re: [PATCH][net-next] net/ipv6: compute anycast address hash only if dev is null

[David Miller]

From: Li RongQing <lirongqing@baidu.com>
Date: Thu,  8 Nov 2018 13:35:40 +0800

> avoid to compute the hash value if dev is not null, since
> hash value is not used
> 
> Signed-off-by: Li RongQing <lirongqing@baidu.com>
> ---
>  net/ipv6/anycast.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/net/ipv6/anycast.c b/net/ipv6/anycast.c
> index 94999058e110..a20e344486cb 100644
> --- a/net/ipv6/anycast.c
> +++ b/net/ipv6/anycast.c
> @@ -433,15 +433,16 @@ static bool ipv6_chk_acast_dev(struct net_device *dev, const struct in6_addr *ad
>  bool ipv6_chk_acast_addr(struct net *net, struct net_device *dev,
>  			 const struct in6_addr *addr)
>  {
> -	unsigned int hash = inet6_acaddr_hash(net, addr);
>  	struct net_device *nh_dev;
>  	struct ifacaddr6 *aca;
>  	bool found = false;
> +	unsigned int hash;
>  
>  	rcu_read_lock();
>  	if (dev)
>  		found = ipv6_chk_acast_dev(dev, addr);
> -	else
> +	else {
> +		hash = inet6_acaddr_hash(net, addr);
>  		hlist_for_each_entry_rcu(aca, &inet6_acaddr_lst[hash],

Please move the hash local variable declaration into this basic block
too, if you're going to do this.

Thanks.