diff mbox

[net-next] ipv4: avoid a test in ip_rt_put()

Message ID 1351499603.7394.199.camel@edumazet-glaptop
State Accepted, archived
Delegated to: David Miller
Headers show

Commit Message

Eric Dumazet Oct. 29, 2012, 8:33 a.m. UTC 
From: Eric Dumazet <edumazet@google.com>

We can save a test in ip_rt_put(), considering dst_release() accepts
a NULL parameter, and dst is first element in rtable.

Add a BUILD_BUG_ON() to catch any change that could break this
assertion.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Cong Wang <amwang@redhat.com>
---
 include/net/route.h |    9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)



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Comments

Amerigo Wang Oct. 29, 2012, 9:09 a.m. UTC | #1 
On Mon, 2012-10-29 at 09:33 +0100, Eric Dumazet wrote:
> From: Eric Dumazet <edumazet@google.com>
> 
> We can save a test in ip_rt_put(), considering dst_release() accepts
> a NULL parameter, and dst is first element in rtable.
> 
> Add a BUILD_BUG_ON() to catch any change that could break this
> assertion.
> 
> Signed-off-by: Eric Dumazet <edumazet@google.com>
> Cc: Cong Wang <amwang@redhat.com>

Acked-by: Cong Wang <amwang@redhat.com>

Thanks!

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David Miller Nov. 3, 2012, 7 p.m. UTC | #2 
From: Cong Wang <amwang@redhat.com>
Date: Mon, 29 Oct 2012 17:09:06 +0800

> On Mon, 2012-10-29 at 09:33 +0100, Eric Dumazet wrote:
>> From: Eric Dumazet <edumazet@google.com>
>> 
>> We can save a test in ip_rt_put(), considering dst_release() accepts
>> a NULL parameter, and dst is first element in rtable.
>> 
>> Add a BUILD_BUG_ON() to catch any change that could break this
>> assertion.
>> 
>> Signed-off-by: Eric Dumazet <edumazet@google.com>
>> Cc: Cong Wang <amwang@redhat.com>
> 
> Acked-by: Cong Wang <amwang@redhat.com>

Applied.
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diff mbox

Patch

diff --git a/include/net/route.h b/include/net/route.h
index bc40b63..2ea40c1 100644
--- a/include/net/route.h
+++ b/include/net/route.h
@@ -198,10 +198,13 @@  struct in_ifaddr;
 extern void fib_add_ifaddr(struct in_ifaddr *);
 extern void fib_del_ifaddr(struct in_ifaddr *, struct in_ifaddr *);
 
-static inline void ip_rt_put(struct rtable * rt)
+static inline void ip_rt_put(struct rtable *rt)
 {
-	if (rt)
-		dst_release(&rt->dst);
+	/* dst_release() accepts a NULL parameter.
+	 * We rely on dst being first structure in struct rtable
+	 */
+	BUILD_BUG_ON(offsetof(struct rtable, dst) != 0);
+	dst_release(&rt->dst);
 }
 
 #define IPTOS_RT_MASK	(IPTOS_TOS_MASK & ~3)