From: Eric Dumazet <dada1@cosmosbay.com>
Date: Thu, 10 Jan 2008 11:55:57 +0000 (-0800)
Subject: [IPV4] ROUTE: fix rcu_dereference() uses in /proc/net/rt_cache
X-Git-Tag: v2.6.24-rc8~7^2~11
X-Git-Url: http://pilppa.com/gitweb/?a=commitdiff_plain;h=0bcceadceb0907094ba4e40bf9a7cd9b080f13fb;p=linux-2.6-omap-h63xx.git

[IPV4] ROUTE: fix rcu_dereference() uses in /proc/net/rt_cache

In rt_cache_get_next(), no need to guard seq->private by a
rcu_dereference() since seq is private to the thread running this
function. Reading seq.private once (as guaranted bu rcu_dereference())
or several time if compiler really is dumb enough wont change the
result.

But we miss real spots where rcu_dereference() are needed, both in
rt_cache_get_first() and rt_cache_get_next()

Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
---

diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index d3377069ce0..28484f396b0 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -283,12 +283,12 @@ static struct rtable *rt_cache_get_first(struct seq_file *seq)
 			break;
 		rcu_read_unlock_bh();
 	}
-	return r;
+	return rcu_dereference(r);
 }
 
 static struct rtable *rt_cache_get_next(struct seq_file *seq, struct rtable *r)
 {
-	struct rt_cache_iter_state *st = rcu_dereference(seq->private);
+	struct rt_cache_iter_state *st = seq->private;
 
 	r = r->u.dst.rt_next;
 	while (!r) {
@@ -298,7 +298,7 @@ static struct rtable *rt_cache_get_next(struct seq_file *seq, struct rtable *r)
 		rcu_read_lock_bh();
 		r = rt_hash_table[st->bucket].chain;
 	}
-	return r;
+	return rcu_dereference(r);
 }
 
 static struct rtable *rt_cache_get_idx(struct seq_file *seq, loff_t pos)