net: core: use this_cpu_ptr per-cpu helper

flush_tasklet is a struct, not a pointer in percpu var.
so use this_cpu_ptr to get the member pointer.
Signed-off-by: Shan Wei <davidshan@tencent.com>
Reviewed-by: Christoph Lameter <cl@linux.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/core/flow.c

@@ -327,11 +327,9 @@ static void flow_cache_flush_tasklet(unsigned long data)
 static void flow_cache_flush_per_cpu(void *data)
 {
 	struct flow_flush_info *info = data;
-	int cpu;
 	struct tasklet_struct *tasklet;
 
-	cpu = smp_processor_id();
-	tasklet = &per_cpu_ptr(info->cache->percpu, cpu)->flush_tasklet;
+	tasklet = this_cpu_ptr(&info->cache->percpu->flush_tasklet);
 	tasklet->data = (unsigned long)info;
 	tasklet_schedule(tasklet);
 }