linux-kernel - [PATCH 3/3] netlink: use generic skb_set_owner

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Date:   Thu, 22 Aug 2019 10:48:33 +0000
From:   Jan Dakinevich <jan.dakinevich@...tuozzo.com>
To:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
CC:     Denis Lunev <den@...tuozzo.com>,
        Konstantin Khorenko <khorenko@...tuozzo.com>,
        "jan.dakinevich@...il.com" <jan.dakinevich@...il.com>,
        Jan Dakinevich <jan.dakinevich@...tuozzo.com>,
        "David S. Miller" <davem@...emloft.net>,
        "Alexey Kuznetsov (C)" <kuznet@....inr.ac.ru>,
        Hideaki YOSHIFUJI <yoshfuji@...ux-ipv6.org>,
        Pablo Neira Ayuso <pablo@...filter.org>,
        Jozsef Kadlecsik <kadlec@...filter.org>,
        Florian Westphal <fw@...len.de>,
        Johannes Berg <johannes.berg@...el.com>,
        David Ahern <dsahern@...il.com>,
        Christian Brauner <christian@...uner.io>,
        Jakub Kicinski <jakub.kicinski@...ronome.com>,
        "Jason A. Donenfeld" <Jason@...c4.com>,
        Stephen Hemminger <stephen@...workplumber.org>,
        Willem de Bruijn <willemb@...gle.com>,
        Cong Wang <xiyou.wangcong@...il.com>,
        Eric Dumazet <edumazet@...gle.com>,
        John Hurley <john.hurley@...ronome.com>,
        Paolo Abeni <pabeni@...hat.com>,
        Jesper Dangaard Brouer <brouer@...hat.com>,
        Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
        Li RongQing <lirongqing@...du.com>,
        Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>,
        Patrick Talbert <ptalbert@...hat.com>,
        Taehee Yoo <ap420073@...il.com>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        Thomas Gleixner <tglx@...utronix.de>,
        Dmitry Safonov <dima@...sta.com>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "netfilter-devel@...r.kernel.org" <netfilter-devel@...r.kernel.org>,
        "coreteam@...filter.org" <coreteam@...filter.org>
Subject: [PATCH 3/3] netlink: use generic skb_set_owner_r()

Since skb destructor is not used for data deallocating,
netlink_skb_set_owner_r() almost completely repeates generic
skb_set_owner_r(). Thus, both netlink_skb_set_owner_r() and
netlink_skb_destructor() are not required anymore.

Signed-off-by: Jan Dakinevich <jan.dakinevich@...tuozzo.com>
---
 net/netlink/af_netlink.c | 23 ++++-------------------
 1 file changed, 4 insertions(+), 19 deletions(-)

diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index 04a3457..b0c2eb2 100644
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -358,21 +358,6 @@ static void netlink_rcv_wake(struct sock *sk)
 		wake_up_interruptible(&nlk->wait);
 }
 
-static void netlink_skb_destructor(struct sk_buff *skb)
-{
-	if (skb->sk != NULL)
-		sock_rfree(skb);
-}
-
-static void netlink_skb_set_owner_r(struct sk_buff *skb, struct sock *sk)
-{
-	WARN_ON(skb->sk != NULL);
-	skb->sk = sk;
-	skb->destructor = netlink_skb_destructor;
-	atomic_add(skb->truesize, &sk->sk_rmem_alloc);
-	sk_mem_charge(sk, skb->truesize);
-}
-
 static void netlink_sock_destruct(struct sock *sk)
 {
 	struct netlink_sock *nlk = nlk_sk(sk);
@@ -1225,7 +1210,7 @@ int netlink_attachskb(struct sock *sk, struct sk_buff *skb,
 		}
 		return 1;
 	}
-	netlink_skb_set_owner_r(skb, sk);
+	skb_set_owner_r(skb, sk);
 	return 0;
 }
 
@@ -1286,7 +1271,7 @@ static int netlink_unicast_kernel(struct sock *sk, struct sk_buff *skb,
 	ret = -ECONNREFUSED;
 	if (nlk->netlink_rcv != NULL) {
 		ret = skb->len;
-		netlink_skb_set_owner_r(skb, sk);
+		skb_set_owner_r(skb, sk);
 		NETLINK_CB(skb).sk = ssk;
 		netlink_deliver_tap_kernel(sk, ssk, skb);
 		nlk->netlink_rcv(skb);
@@ -1367,7 +1352,7 @@ static int netlink_broadcast_deliver(struct sock *sk, struct sk_buff *skb)
 
 	if (atomic_read(&sk->sk_rmem_alloc) <= sk->sk_rcvbuf &&
 	    !test_bit(NETLINK_S_CONGESTED, &nlk->state)) {
-		netlink_skb_set_owner_r(skb, sk);
+		skb_set_owner_r(skb, sk);
 		__netlink_sendskb(sk, skb);
 		return atomic_read(&sk->sk_rmem_alloc) > (sk->sk_rcvbuf >> 1);
 	}
@@ -2227,7 +2212,7 @@ static int netlink_dump(struct sock *sk)
 	 * single netdev. The outcome is MSG_TRUNC error.
 	 */
 	skb_reserve(skb, skb_tailroom(skb) - alloc_size);
-	netlink_skb_set_owner_r(skb, sk);
+	skb_set_owner_r(skb, sk);
 
 	if (nlk->dump_done_errno > 0) {
 		cb->extack = &extack;
-- 
2.1.4