From mboxrd@z Thu Jan  1 00:00:00 1970
From: David Ahern <dsahern@gmail.com>
Subject: Re: [PATCH 03/11] net: fib_multipath_hash() - use new style struct
 initializer instead of memset
Date: Fri, 28 Sep 2018 11:47:48 -0600
Message-ID: <9aecd068-1fe4-7d83-6fc5-87ec90d69c13@gmail.com>
References: <20180927230017.15398-1-zenczykowski@gmail.com>
 <20180927230017.15398-3-zenczykowski@gmail.com>
Mime-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: 8bit
Cc: netdev@vger.kernel.org
To: =?UTF-8?Q?Maciej_=c5=bbenczykowski?= <zenczykowski@gmail.com>,
        =?UTF-8?Q?Maciej_=c5=bbenczykowski?= <maze@google.com>,
        "David S . Miller" <davem@davemloft.net>
Return-path: <netdev-owner@vger.kernel.org>
Received: from mail-pg1-f195.google.com ([209.85.215.195]:42212 "EHLO
        mail-pg1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
        with ESMTP id S1726238AbeI2AMn (ORCPT
        <rfc822;netdev@vger.kernel.org>); Fri, 28 Sep 2018 20:12:43 -0400
Received: by mail-pg1-f195.google.com with SMTP id i4-v6so4367378pgq.9
        for <netdev@vger.kernel.org>; Fri, 28 Sep 2018 10:47:52 -0700 (PDT)
In-Reply-To: <20180927230017.15398-3-zenczykowski@gmail.com>
Content-Language: en-US
Sender: netdev-owner@vger.kernel.org
List-ID: <netdev.vger.kernel.org>

On 9/27/18 5:00 PM, Maciej Żenczykowski wrote:
> From: Maciej Żenczykowski <maze@google.com>
> 
> Signed-off-by: Maciej Żenczykowski <maze@google.com>
> ---
>  net/ipv4/route.c | 6 +-----
>  1 file changed, 1 insertion(+), 5 deletions(-)
> 
> diff --git a/net/ipv4/route.c b/net/ipv4/route.c
> index 048919713f4e..17953a52fbd0 100644
> --- a/net/ipv4/route.c
> +++ b/net/ipv4/route.c
> @@ -1821,12 +1821,11 @@ static void ip_multipath_l3_keys(const struct sk_buff *skb,
>  int fib_multipath_hash(const struct net *net, const struct flowi4 *fl4,
>  		       const struct sk_buff *skb, struct flow_keys *flkeys)
>  {
> -	struct flow_keys hash_keys;
> +	struct flow_keys hash_keys = {};
>  	u32 mhash;
>  
>  	switch (net->ipv4.sysctl_fib_multipath_hash_policy) {
>  	case 0:
> -		memset(&hash_keys, 0, sizeof(hash_keys));
>  		hash_keys.control.addr_type = FLOW_DISSECTOR_KEY_IPV4_ADDRS;
>  		if (skb) {
>  			ip_multipath_l3_keys(skb, &hash_keys);
> @@ -1845,8 +1844,6 @@ int fib_multipath_hash(const struct net *net, const struct flowi4 *fl4,
>  			if (skb->l4_hash)
>  				return skb_get_hash_raw(skb) >> 1;
>  
> -			memset(&hash_keys, 0, sizeof(hash_keys));
> -
>  			if (!flkeys) {
>  				skb_flow_dissect_flow_keys(skb, &keys, flag);
>  				flkeys = &keys;
> @@ -1859,7 +1856,6 @@ int fib_multipath_hash(const struct net *net, const struct flowi4 *fl4,
>  			hash_keys.ports.dst = flkeys->ports.dst;
>  			hash_keys.basic.ip_proto = flkeys->basic.ip_proto;
>  		} else {
> -			memset(&hash_keys, 0, sizeof(hash_keys));
>  			hash_keys.control.addr_type = FLOW_DISSECTOR_KEY_IPV4_ADDRS;
>  			hash_keys.addrs.v4addrs.src = fl4->saddr;
>  			hash_keys.addrs.v4addrs.dst = fl4->daddr;
> 

NACK on this one.

This is the hot path and the memset was done right before use for least
overhead.