net: core: add devm_netdev_alloc_pcpu_stats

We have netdev_alloc_pcpu_stats(), and we have devm_alloc_percpu().
Add a managed version of netdev_alloc_pcpu_stats, e.g. for allocating
the per-cpu stats in the probe() callback of a driver. It needs to be
a macro for dealing properly with the type argument.
Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

include/linux/netdevice.h

@@ -2596,6 +2596,20 @@ static inline void dev_lstats_add(struct net_device *dev, unsigned int len)
 #define netdev_alloc_pcpu_stats(type)					\
 	__netdev_alloc_pcpu_stats(type, GFP_KERNEL)
 
+#define devm_netdev_alloc_pcpu_stats(dev, type)				\
+({									\
+	typeof(type) __percpu *pcpu_stats = devm_alloc_percpu(dev, type);\
+	if (pcpu_stats) {						\
+		int __cpu;						\
+		for_each_possible_cpu(__cpu) {				\
+			typeof(type) *stat;				\
+			stat = per_cpu_ptr(pcpu_stats, __cpu);		\
+			u64_stats_init(&stat->syncp);			\
+		}							\
+	}								\
+	pcpu_stats;							\
+})
+
 enum netdev_lag_tx_type {
 	NETDEV_LAG_TX_TYPE_UNKNOWN,
 	NETDEV_LAG_TX_TYPE_RANDOM,