[PATCH net-next v3] net/core: Export dev_core_stats_*_inc()

[Yajun Deng <yajun.deng@linux.dev>]

Although there is a kfree_skb_reason() helper function that can be used to
find the reason why this skb is dropped, but most callers didn't increase
one of rx_dropped, tx_dropped, rx_nohandler and rx_otherhost_dropped.

For the users, people are more concerned about why the dropped in ip
is increasing. So we can export dev_core_stats_rx_dropped_inc sets,
which users would trace them know why rx_dropped is increasing.

Export dev_core_stats_{rx_dropped, tx_dropped, rx_nohandler,
rx_otherhost_dropped}_inc for trace. Also, move dev_core_stats()
and netdev_core_stats_alloc() to dev.c, as they are not called
externally.

Signed-off-by: Yajun Deng <yajun.deng@linux.dev>
---
v3: __cold should be added to the netdev_core_stats_alloc().
v2: use __cold instead of inline in dev_core_stats().
v1: https://lore.kernel.org/netdev/20230911082016.3694700-1-yajun.deng@linux.dev/
---
 include/linux/netdevice.h | 32 +++++---------------------------
 net/core/dev.c            | 32 ++++++++++++++++++++++++++++++--
 2 files changed, 35 insertions(+), 29 deletions(-)

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 0896aaa91dd7..879b01c85ba4 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -3954,6 +3954,11 @@ int dev_forward_skb_nomtu(struct net_device *dev, struct sk_buff *skb);
 bool is_skb_forwardable(const struct net_device *dev,
 			const struct sk_buff *skb);
 
+void dev_core_stats_rx_dropped_inc(struct net_device *dev);
+void dev_core_stats_tx_dropped_inc(struct net_device *dev);
+void dev_core_stats_rx_nohandler_inc(struct net_device *dev);
+void dev_core_stats_rx_otherhost_dropped_inc(struct net_device *dev);
+
 static __always_inline bool __is_skb_forwardable(const struct net_device *dev,
 						 const struct sk_buff *skb,
 						 const bool check_mtu)
@@ -3980,33 +3985,6 @@ static __always_inline bool __is_skb_forwardable(const struct net_device *dev,
 	return false;
 }
 
-struct net_device_core_stats __percpu *netdev_core_stats_alloc(struct net_device *dev);
-
-static inline struct net_device_core_stats __percpu *dev_core_stats(struct net_device *dev)
-{
-	/* This READ_ONCE() pairs with the write in netdev_core_stats_alloc() */
-	struct net_device_core_stats __percpu *p = READ_ONCE(dev->core_stats);
-
-	if (likely(p))
-		return p;
-
-	return netdev_core_stats_alloc(dev);
-}
-
-#define DEV_CORE_STATS_INC(FIELD)						\
-static inline void dev_core_stats_##FIELD##_inc(struct net_device *dev)		\
-{										\
-	struct net_device_core_stats __percpu *p;				\
-										\
-	p = dev_core_stats(dev);						\
-	if (p)									\
-		this_cpu_inc(p->FIELD);						\
-}
-DEV_CORE_STATS_INC(rx_dropped)
-DEV_CORE_STATS_INC(tx_dropped)
-DEV_CORE_STATS_INC(rx_nohandler)
-DEV_CORE_STATS_INC(rx_otherhost_dropped)
-
 static __always_inline int ____dev_forward_skb(struct net_device *dev,
 					       struct sk_buff *skb,
 					       const bool check_mtu)
diff --git a/net/core/dev.c b/net/core/dev.c
index ccff2b6ef958..98592e4c1df0 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -10475,7 +10475,7 @@ void netdev_stats_to_stats64(struct rtnl_link_stats64 *stats64,
 }
 EXPORT_SYMBOL(netdev_stats_to_stats64);
 
-struct net_device_core_stats __percpu *netdev_core_stats_alloc(struct net_device *dev)
+static __cold struct net_device_core_stats __percpu *netdev_core_stats_alloc(struct net_device *dev)
 {
 	struct net_device_core_stats __percpu *p;
 
@@ -10488,7 +10488,35 @@ struct net_device_core_stats __percpu *netdev_core_stats_alloc(struct net_device
 	/* This READ_ONCE() pairs with the cmpxchg() above */
 	return READ_ONCE(dev->core_stats);
 }
-EXPORT_SYMBOL(netdev_core_stats_alloc);
+
+static inline struct net_device_core_stats __percpu *dev_core_stats(struct net_device *dev)
+{
+	/* This READ_ONCE() pairs with the write in netdev_core_stats_alloc() */
+	struct net_device_core_stats __percpu *p = READ_ONCE(dev->core_stats);
+
+	if (likely(p))
+		return p;
+
+	return netdev_core_stats_alloc(dev);
+}
+
+#define DEV_CORE_STATS_INC(FIELD)				\
+void dev_core_stats_##FIELD##_inc(struct net_device *dev)	\
+{								\
+	struct net_device_core_stats __percpu *p;		\
+								\
+	p = dev_core_stats(dev);				\
+	if (p)							\
+		this_cpu_inc(p->FIELD);				\
+}								\
+EXPORT_SYMBOL(dev_core_stats_##FIELD##_inc)
+
+DEV_CORE_STATS_INC(rx_dropped);
+DEV_CORE_STATS_INC(tx_dropped);
+DEV_CORE_STATS_INC(rx_nohandler);
+DEV_CORE_STATS_INC(rx_otherhost_dropped);
+
+#undef DEV_CORE_STATS_INC
 
 /**
  *	dev_get_stats	- get network device statistics
-- 
2.25.1