core: Replace __get_cpu_var with __this_cpu_read if not used for an address.
__get_cpu_var() can be replaced with this_cpu_read and will then use a
single read instruction with implied address calculation to access the
correct per cpu instance.
However, the address of a per cpu variable passed to __this_cpu_read()
cannot be determined (since it's an implied address conversion through
segment prefixes). Therefore apply this only to uses of __get_cpu_var
where the address of the variable is not used.
Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: Hugh Dickins <hughd@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Acked-by: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
diff --git a/mm/slab.c b/mm/slab.c
index b1e40da..316d755 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -829,12 +829,12 @@
static void next_reap_node(void)
{
- int node = __get_cpu_var(slab_reap_node);
+ int node = __this_cpu_read(slab_reap_node);
node = next_node(node, node_online_map);
if (unlikely(node >= MAX_NUMNODES))
node = first_node(node_online_map);
- __get_cpu_var(slab_reap_node) = node;
+ __this_cpu_write(slab_reap_node, node);
}
#else
@@ -1012,7 +1012,7 @@
*/
static void reap_alien(struct kmem_cache *cachep, struct kmem_list3 *l3)
{
- int node = __get_cpu_var(slab_reap_node);
+ int node = __this_cpu_read(slab_reap_node);
if (l3->alien) {
struct array_cache *ac = l3->alien[node];