/* * Fast batching percpu counters. */ #include <linux/percpu_counter.h>#include <linux/module.h> void percpu_counter_mod(struct percpu_counter *fbc, s32 amount){	long count;	s32 *pcount;	int cpu = get_cpu(); 	pcount = per_cpu_ptr(fbc->counters, cpu);	count = *pcount + amount;	if (count >= FBC_BATCH || count <= -FBC_BATCH) {		spin_lock(&fbc->lock);		fbc->count += count;		*pcount = 0;		spin_unlock(&fbc->lock);	} else {		*pcount = count;	}	put_cpu();}EXPORT_SYMBOL(percpu_counter_mod); /* * Add up all the per-cpu counts, return the result.  This is a more accurate * but much slower version of percpu_counter_read_positive() */s64 percpu_counter_sum(struct percpu_counter *fbc){	s64 ret;	int cpu; 	spin_lock(&fbc->lock);	ret = fbc->count;	for_each_possible_cpu(cpu) {		s32 *pcount = per_cpu_ptr(fbc->counters, cpu);		ret += *pcount;	}	spin_unlock(&fbc->lock);	return ret < 0 ? 0 : ret;}EXPORT_SYMBOL(percpu_counter_sum);