ipc/util.c, ipc_rcu_alloc: cacheline align allocation

[~andy/linux] / ipc / util.c

diff --git a/ipc/util.c b/ipc/util.c
index a0c139f3d1f3ea0ef62b25939db8d30ff52d41c3..4704223bfad48e41258e018266feb9f5ed4b860e 100644 (file)
--- a/ipc/util.c
+++ b/ipc/util.c
@@ -468,9 +468,7 @@ void ipc_free(void* ptr, int size)
 struct ipc_rcu {
        struct rcu_head rcu;
        atomic_t refcount;
-       /* "void *" makes sure alignment of following data is sane. */
-       void *data[0];
-};
+} ____cacheline_aligned_in_smp;
 
 /**
  *     ipc_rcu_alloc   -       allocate ipc and rcu space 
@@ -488,12 +486,14 @@ void *ipc_rcu_alloc(int size)
        if (unlikely(!out))
                return NULL;
        atomic_set(&out->refcount, 1);
-       return out->data;
+       return out + 1;
 }
 
 int ipc_rcu_getref(void *ptr)
 {
-       return atomic_inc_not_zero(&container_of(ptr, struct ipc_rcu, data)->refcount);
+       struct ipc_rcu *p = ((struct ipc_rcu *)ptr) - 1;
+
+       return atomic_inc_not_zero(&p->refcount);
 }
 
 /**
@@ -507,7 +507,7 @@ static void ipc_schedule_free(struct rcu_head *head)
 
 void ipc_rcu_putref(void *ptr)
 {
-       struct ipc_rcu *p = container_of(ptr, struct ipc_rcu, data);
+       struct ipc_rcu *p = ((struct ipc_rcu *)ptr) - 1;
 
        if (!atomic_dec_and_test(&p->refcount))
                return;