Patchwork [RFC(v2),net-next,08/13] ipv6: Do not deoend on rt->n in ip6_dst_lookup_tail().

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Submitter YOSHIFUJI Hideaki / 吉藤英明
Date Jan. 15, 2013, 4:46 p.m.
Message ID <50F587CF.1090306@linux-ipv6.org>
Download mbox | patch
Permalink /patch/212234/
State RFC
Delegated to: David Miller
Headers show

Comments

YOSHIFUJI Hideaki / 吉藤英明 - Jan. 15, 2013, 4:46 p.m.
Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
---
 net/ipv6/ip6_output.c |    8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)
WANG Cong - Jan. 16, 2013, 6:49 a.m.
s/deoend/depend/ in $subject...

On 01/16/2013 12:46 AM, YOSHIFUJI Hideaki wrote:
> Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
> ---
>   net/ipv6/ip6_output.c |    8 ++++++--
>   1 file changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
> index 9fc5d1d..b2fe048 100644
> --- a/net/ipv6/ip6_output.c
> +++ b/net/ipv6/ip6_output.c
> @@ -921,8 +921,12 @@ static int ip6_dst_lookup_tail(struct sock *sk,
>   	 * dst entry of the nexthop router
>   	 */
>   	rt = (struct rt6_info *) *dst;
> -	n = rt->n;
> -	if (n && !(n->nud_state & NUD_VALID)) {
> +	rcu_read_lock_bh();
> +	n = __ipv6_neigh_lookup_noref(rt->dst.dev, rt6_nexthop(rt, &fl6->daddr));
> +	err = n && !(n->nud_state & NUD_VALID) ? -EINVAL : 0;
> +	rcu_read_unlock_bh();
> +
> +	if (err) {

Are you sure the logic here equals?

In the original code, we could return 0 even we enter this if branch,
but after your patch, it seems it will return -EINVAL?

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YOSHIFUJI Hideaki / 吉藤英明 - Jan. 16, 2013, 12:27 p.m.
Cong Wang wrote:
> s/deoend/depend/ in $subject...
> 
> On 01/16/2013 12:46 AM, YOSHIFUJI Hideaki wrote:
>> Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
>> ---
>>   net/ipv6/ip6_output.c |    8 ++++++--
>>   1 file changed, 6 insertions(+), 2 deletions(-)
>>
>> diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
>> index 9fc5d1d..b2fe048 100644
>> --- a/net/ipv6/ip6_output.c
>> +++ b/net/ipv6/ip6_output.c
>> @@ -921,8 +921,12 @@ static int ip6_dst_lookup_tail(struct sock *sk,
>>   	 * dst entry of the nexthop router
>>   	 */
>>   	rt = (struct rt6_info *) *dst;
>> -	n = rt->n;
>> -	if (n && !(n->nud_state & NUD_VALID)) {
>> +	rcu_read_lock_bh();
>> +	n = __ipv6_neigh_lookup_noref(rt->dst.dev, rt6_nexthop(rt, &fl6->daddr));
>> +	err = n && !(n->nud_state & NUD_VALID) ? -EINVAL : 0;
>> +	rcu_read_unlock_bh();
>> +
>> +	if (err) {
> 
> Are you sure the logic here equals?
> 
> In the original code, we could return 0 even we enter this if branch,
> but after your patch, it seems it will return -EINVAL?
> 

err is always updated after the branch, or return 0;

--yoshfuji
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Patch

diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
index 9fc5d1d..b2fe048 100644
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -921,8 +921,12 @@  static int ip6_dst_lookup_tail(struct sock *sk,
 	 * dst entry of the nexthop router
 	 */
 	rt = (struct rt6_info *) *dst;
-	n = rt->n;
-	if (n && !(n->nud_state & NUD_VALID)) {
+	rcu_read_lock_bh();
+	n = __ipv6_neigh_lookup_noref(rt->dst.dev, rt6_nexthop(rt, &fl6->daddr));
+	err = n && !(n->nud_state & NUD_VALID) ? -EINVAL : 0;
+	rcu_read_unlock_bh();
+
+	if (err) {
 		struct inet6_ifaddr *ifp;
 		struct flowi6 fl_gw6;
 		int redirect;