kernel: disable pre-emption when accessing per-cpu variables

include/socks/percpu.h

@@ -3,6 +3,7 @@
 
 #include <socks/status.h>
 #include <socks/compiler.h>
+#include <socks/sched.h>
 
 #ifdef __cplusplus
 extern "C" {
@@ -11,9 +12,13 @@ extern "C" {
 #define DEFINE_PERCPU_VAR(type, name) \
 	__section(".data.percpu") type name
 
-#define percpu_get(var) __percpu_get(var)
+#define percpu_get(var) \
+	__extension__({ \
+	preempt_disable(); \
+	__percpu_get(var); \
+	})
 
-#define percpu_put(var)
+#define percpu_put(var) preempt_enable();
 
 extern kern_status_t init_per_cpu_areas(void);
 extern void *__percpu_get(void *var);