From mboxrd@z Thu Jan  1 00:00:00 1970
From: "David S. Miller" <davem@davemloft.net>
Subject: Re: [PATCH] netlink: defer socket destruction a bit
Date: Thu, 19 May 2005 13:08:59 -0700 (PDT)
Message-ID: <20050519.130859.115641546.davem@davemloft.net>
References: <20050511230309.GA21547@gondor.apana.org.au>
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	<20050512103639.GA25631@gondor.apana.org.au>
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To: herbert@gondor.apana.org.au
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From: Herbert Xu <herbert@gondor.apana.org.au>
Date: Thu, 12 May 2005 20:36:39 +1000

> On Thu, May 12, 2005 at 11:57:01AM +0200, Tommy Christensen wrote:
> > 
> > I moved the call to skb_orphan in the other patch, as you
> > suggested.  I think that also makes this patch safe as it is.
> > 
> > Right?
> 
> Indeed it is.  This also means that we don't hold onto the skb's
> share of rmalloc quota for an excessive amount of time if the
> number of broadcast sockets is large.

Ok, I think I got all the patches straight.  All of Tommy's
patches combined together look like this diff in my tree.
Please double check it.

Thanks.

diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -735,11 +735,15 @@ static inline int do_one_broadcast(struc
 
 	sock_hold(sk);
 	if (p->skb2 == NULL) {
-		if (atomic_read(&p->skb->users) != 1) {
+		if (skb_shared(p->skb)) {
 			p->skb2 = skb_clone(p->skb, p->allocation);
 		} else {
-			p->skb2 = p->skb;
-			atomic_inc(&p->skb->users);
+			p->skb2 = skb_get(p->skb);
+			/*
+			 * skb ownership may have been set when
+			 * delivered to a previous socket.
+			 */
+			skb_orphan(p->skb2);
 		}
 	}
 	if (p->skb2 == NULL) {
@@ -785,11 +789,12 @@ int netlink_broadcast(struct sock *ssk, 
 	sk_for_each_bound(sk, node, &nl_table[ssk->sk_protocol].mc_list)
 		do_one_broadcast(sk, &info);
 
+	kfree_skb(skb);
+
 	netlink_unlock_table();
 
 	if (info.skb2)
 		kfree_skb(info.skb2);
-	kfree_skb(skb);
 
 	if (info.delivered) {
 		if (info.congested && (allocation & __GFP_WAIT))