+ decs += per_cpu_ptr(mod->refptr, cpu)->decs;
+ /*
+ * ensure the incs are added up after the decs.
+ * module_put ensures incs are visible before decs with smp_wmb.
+ *
+ * This 2-count scheme avoids the situation where the refcount
+ * for CPU0 is read, then CPU0 increments the module refcount,
+ * then CPU1 drops that refcount, then the refcount for CPU1 is
+ * read. We would record a decrement but not its corresponding
+ * increment so we would see a low count (disaster).
+ *
+ * Rare situation? But module_refcount can be preempted, and we
+ * might be tallying up 4096+ CPUs. So it is not impossible.
+ */
+ smp_rmb();
+ for_each_possible_cpu(cpu)
+ incs += per_cpu_ptr(mod->refptr, cpu)->incs;
+ return incs - decs;