netdev - [PATCH v2 net-next] tcp/dccp: Move initialisation of refcounted into if block.

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Message-ID: <20200324113331.29031-1-kuniyu@amazon.co.jp>
Date:   Tue, 24 Mar 2020 20:33:31 +0900
From:   Kuniyuki Iwashima <kuniyu@...zon.co.jp>
To:     "David S . Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Eric Dumazet <edumazet@...gle.com>,
        Gerrit Renker <gerrit@....abdn.ac.uk>,
        Alexey Kuznetsov <kuznet@....inr.ac.ru>,
        "Hideaki YOSHIFUJI" <yoshfuji@...ux-ipv6.org>
CC:     <dccp@...r.kernel.org>, <netdev@...r.kernel.org>,
        Kuniyuki Iwashima <kuni1840@...il.com>,
        Kuniyuki Iwashima <kuniyu@...zon.co.jp>,
        <osa-contribution-log@...zon.com>
Subject: [PATCH v2 net-next] tcp/dccp: Move initialisation of refcounted into if block.

The refcounted seems to be initialised at most three times, but the
complier can optimize that and the refcounted is initialised only at once.

  - __inet_lookup_skb() sets it true.
  - skb_steal_sock() is false and __inet_lookup() sets it true.
  - __inet_lookup_established() is false and __inet_lookup() sets it false.

The code is bit confusing, so this patch makes it more readable so that no
one doubt about the complier optimization.

Signed-off-by: Kuniyuki Iwashima <kuniyu@...zon.co.jp>
---
 include/net/inet6_hashtables.h | 11 +++++++----
 include/net/inet_hashtables.h  | 11 +++++++----
 2 files changed, 14 insertions(+), 8 deletions(-)

diff --git a/include/net/inet6_hashtables.h b/include/net/inet6_hashtables.h
index fe96bf247aac..9b6c97100d54 100644
--- a/include/net/inet6_hashtables.h
+++ b/include/net/inet6_hashtables.h
@@ -70,9 +70,11 @@ static inline struct sock *__inet6_lookup(struct net *net,
 	struct sock *sk = __inet6_lookup_established(net, hashinfo, saddr,
 						     sport, daddr, hnum,
 						     dif, sdif);
-	*refcounted = true;
-	if (sk)
+	if (sk) {
+		*refcounted = true;
 		return sk;
+	}
+
 	*refcounted = false;
 	return inet6_lookup_listener(net, hashinfo, skb, doff, saddr, sport,
 				     daddr, hnum, dif, sdif);
@@ -87,9 +89,10 @@ static inline struct sock *__inet6_lookup_skb(struct inet_hashinfo *hashinfo,
 {
 	struct sock *sk = skb_steal_sock(skb);
 
-	*refcounted = true;
-	if (sk)
+	if (sk) {
+		*refcounted = true;
 		return sk;
+	}
 
 	return __inet6_lookup(dev_net(skb_dst(skb)->dev), hashinfo, skb,
 			      doff, &ipv6_hdr(skb)->saddr, sport,
diff --git a/include/net/inet_hashtables.h b/include/net/inet_hashtables.h
index d0019d3395cf..aa859bf8607b 100644
--- a/include/net/inet_hashtables.h
+++ b/include/net/inet_hashtables.h
@@ -345,9 +345,11 @@ static inline struct sock *__inet_lookup(struct net *net,
 
 	sk = __inet_lookup_established(net, hashinfo, saddr, sport,
 				       daddr, hnum, dif, sdif);
-	*refcounted = true;
-	if (sk)
+	if (sk) {
+		*refcounted = true;
 		return sk;
+	}
+
 	*refcounted = false;
 	return __inet_lookup_listener(net, hashinfo, skb, doff, saddr,
 				      sport, daddr, hnum, dif, sdif);
@@ -382,9 +384,10 @@ static inline struct sock *__inet_lookup_skb(struct inet_hashinfo *hashinfo,
 	struct sock *sk = skb_steal_sock(skb);
 	const struct iphdr *iph = ip_hdr(skb);
 
-	*refcounted = true;
-	if (sk)
+	if (sk) {
+		*refcounted = true;
 		return sk;
+	}
 
 	return __inet_lookup(dev_net(skb_dst(skb)->dev), hashinfo, skb,
 			     doff, iph->saddr, sport,
-- 
2.17.2 (Apple Git-113)