[PATCH net-next] net neighbour,decnet: Ensure to align device private data on preferred alignment.

[PATCH net-next] net neighbour,decnet: Ensure to align device private data on preferred alignment.

[YOSHIFUJI Hideaki]

To allow both of protocol-specific data and device-specific data
attached with neighbour entry, and to eliminate size calculation
cost when allocating entry, sizeof protocol-speicic data must be
multiple of NEIGH_PRIV_ALIGN.  On 64bit archs,
sizeof(struct dn_neigh) is multiple of NEIGH_PRIV_ALIGN, but on
32bit archs, it was not.

Introduce NEIGH_ENTRY_SPACE() macro to ensure that protocol-specific
entry-size meets our requirement.

Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
---
 include/net/neighbour.h |    1 +
 net/decnet/dn_neigh.c   |    2 +-
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/include/net/neighbour.h b/include/net/neighbour.h
index 629ee57..7e748ad 100644
--- a/include/net/neighbour.h
+++ b/include/net/neighbour.h
@@ -181,6 +181,7 @@ struct neigh_table {
 };
 
 #define NEIGH_PRIV_ALIGN	sizeof(long long)
+#define NEIGH_ENTRY_SIZE(size)	ALIGN((size), NEIGH_PRIV_ALIGN)
 
 static inline void *neighbour_priv(const struct neighbour *n)
 {
diff --git a/net/decnet/dn_neigh.c b/net/decnet/dn_neigh.c
index 3aede1b..856636a 100644
--- a/net/decnet/dn_neigh.c
+++ b/net/decnet/dn_neigh.c
@@ -95,7 +95,7 @@ static u32 dn_neigh_hash(const void *pkey,
 
 struct neigh_table dn_neigh_table = {
 	.family =			PF_DECnet,
-	.entry_size =			sizeof(struct dn_neigh),
+	.entry_size =			NEIGH_ENTRY_SIZE(sizeof(struct dn_neigh)),
 	.key_len =			sizeof(__le16),
 	.hash =				dn_neigh_hash,
 	.constructor =			dn_neigh_construct,
-- 
1.7.9.5

Re: [PATCH net-next] net neighbour,decnet: Ensure to align device private data on preferred alignment.

[David Miller]

From: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Date: Sun, 10 Feb 2013 02:00:59 +0900

> To allow both of protocol-specific data and device-specific data
> attached with neighbour entry, and to eliminate size calculation
> cost when allocating entry, sizeof protocol-speicic data must be
> multiple of NEIGH_PRIV_ALIGN.  On 64bit archs,
> sizeof(struct dn_neigh) is multiple of NEIGH_PRIV_ALIGN, but on
> 32bit archs, it was not.
> 
> Introduce NEIGH_ENTRY_SPACE() macro to ensure that protocol-specific
> entry-size meets our requirement.
> 
> Reported-by: Fengguang Wu <fengguang.wu@intel.com>
> Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>

Applied.