rhashtable: ensure cache line alignment on bucket_table

struct bucket_table contains mostly read fields :

size, locks_mask, locks.

Make sure these are not sharing a cache line with buckets[]
Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/rhashtable.h

@@ -57,7 +57,8 @@ struct bucket_table {
 	size_t			size;
 	unsigned int		locks_mask;
 	spinlock_t		*locks;
-	struct rhash_head __rcu		*buckets[];
+
+	struct rhash_head __rcu	*buckets[] ____cacheline_aligned_in_smp;
 };
 
 typedef u32 (*rht_hashfn_t)(const void *data, u32 len, u32 seed);