[PATCH v2 1/2] netpoll: Make netpoll_send_udp return status instead of void

[Maksym Kutsevol <max@kutsevol.com>]

netpoll_send_udp can return if send was successful.
It will allow client code to be aware of the send status.

Possible return values are the result of __netpoll_send_skb (cast to int)
and -ENOMEM. This doesn't cover the case when TX was not successful
instantaneously and was scheduled for later, __netpoll__send_skb returns
success in that case.

Signed-off-by: Maksym Kutsevol <max@kutsevol.com>
---
Used in the next patch to expose send failure stats in netconsole

Changelog:

v2: No changes, resend.

v1:
 * https://lore.kernel.org/netdev/20240824215130.2134153-1-max@kutsevol.com/

 include/linux/netpoll.h | 2 +-
 net/core/netpoll.c      | 6 +++---
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/include/linux/netpoll.h b/include/linux/netpoll.h
index bd19c4b91e31..10ceef618e40 100644
--- a/include/linux/netpoll.h
+++ b/include/linux/netpoll.h
@@ -56,7 +56,7 @@ static inline void netpoll_poll_disable(struct net_device *dev) { return; }
 static inline void netpoll_poll_enable(struct net_device *dev) { return; }
 #endif
 
-void netpoll_send_udp(struct netpoll *np, const char *msg, int len);
+int netpoll_send_udp(struct netpoll *np, const char *msg, int len);
 void netpoll_print_options(struct netpoll *np);
 int netpoll_parse_options(struct netpoll *np, char *opt);
 int __netpoll_setup(struct netpoll *np, struct net_device *ndev);
diff --git a/net/core/netpoll.c b/net/core/netpoll.c
index d657b042d5a0..664343e3b688 100644
--- a/net/core/netpoll.c
+++ b/net/core/netpoll.c
@@ -395,7 +395,7 @@ netdev_tx_t netpoll_send_skb(struct netpoll *np, struct sk_buff *skb)
 }
 EXPORT_SYMBOL(netpoll_send_skb);
 
-void netpoll_send_udp(struct netpoll *np, const char *msg, int len)
+int netpoll_send_udp(struct netpoll *np, const char *msg, int len)
 {
 	int total_len, ip_len, udp_len;
 	struct sk_buff *skb;
@@ -419,7 +419,7 @@ void netpoll_send_udp(struct netpoll *np, const char *msg, int len)
 	skb = find_skb(np, total_len + np->dev->needed_tailroom,
 		       total_len - len);
 	if (!skb)
-		return;
+		return -ENOMEM;
 
 	skb_copy_to_linear_data(skb, msg, len);
 	skb_put(skb, len);
@@ -495,7 +495,7 @@ void netpoll_send_udp(struct netpoll *np, const char *msg, int len)
 
 	skb->dev = np->dev;
 
-	netpoll_send_skb(np, skb);
+	return (int)netpoll_send_skb(np, skb);
 }
 EXPORT_SYMBOL(netpoll_send_udp);
 

base-commit: 3a0504d54b3b57f0d7bf3d9184a00c9f8887f6d7
-- 
2.43.5