net neighbour, decnet: Ensure to align device private data on preferred alignment.

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>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 2 insertions, 1 deletions

diff --git a/include/net/neighbour.h b/include/net/neighbour.h
index 629ee573c6d0..7e748ad8b50c 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 3aede1b459fd..856636addd76 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,