net: add __netdev_alloc_pcpu_stats() to indicate gfp flags

nf_tables may create percpu counters from the packet path through its
dynamic set instantiation infrastructure, so we need a way to allocate
this through GFP_ATOMIC.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Acked-by: David S. Miller <davem@davemloft.net>

include/linux/netdevice.h

@@ -2068,9 +2068,9 @@ struct pcpu_sw_netstats {
 	struct u64_stats_sync   syncp;
 };
 
-#define netdev_alloc_pcpu_stats(type)				\
+#define __netdev_alloc_pcpu_stats(type, gfp)				\
 ({									\
-	typeof(type) __percpu *pcpu_stats = alloc_percpu(type); \
+	typeof(type) __percpu *pcpu_stats = alloc_percpu_gfp(type, gfp);\
 	if (pcpu_stats)	{						\
 		int __cpu;						\
 		for_each_possible_cpu(__cpu) {				\
@@ -2082,6 +2082,9 @@ struct pcpu_sw_netstats {
 	pcpu_stats;							\
 })
 
+#define netdev_alloc_pcpu_stats(type)					\
+	__netdev_alloc_pcpu_stats(type, GFP_KERNEL);
+
 #include <linux/notifier.h>
 
 /* netdevice notifier chain. Please remember to update the rtnetlink