[PATCH v3 1/2] ns: pad refcount

[Mateusz Guzik <mjguzik@gmail.com>]

Note no effort is made to make sure structs embedding the namespace are
themselves aligned, so this is not guaranteed to eliminate cacheline
bouncing due to refcount management.

Signed-off-by: Mateusz Guzik <mjguzik@gmail.com>
---
 include/linux/ns/ns_common_types.h | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/include/linux/ns/ns_common_types.h b/include/linux/ns/ns_common_types.h
index b332b019b29c..0014fbc1c626 100644
--- a/include/linux/ns/ns_common_types.h
+++ b/include/linux/ns/ns_common_types.h
@@ -108,11 +108,13 @@ extern const struct proc_ns_operations utsns_operations;
  * @ns_tree: namespace tree nodes and active reference count
  */
 struct ns_common {
+	struct {
+		refcount_t __ns_ref; /* do not use directly */
+	} ____cacheline_aligned_in_smp;
 	u32 ns_type;
 	struct dentry *stashed;
 	const struct proc_ns_operations *ops;
 	unsigned int inum;
-	refcount_t __ns_ref; /* do not use directly */
 	union {
 		struct ns_tree;
 		struct rcu_head ns_rcu;
-- 
2.48.1