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>
---
 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 cd4e28db0cbd..b1ba8d6331a5 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 94b7f07a952f..1f36f351b5f9 100644
--- a/net/core/netpoll.c
+++ b/net/core/netpoll.c
@@ -390,7 +390,7 @@ 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;
@@ -414,7 +414,7 @@ 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);
@@ -490,7 +490,7 @@ 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);
 

-- 
2.43.5

On Sun, Oct 27, 2024 at 12:59:41PM -0700, Maksym Kutsevol wrote:
> 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>

Reviewed-by: Breno Leitao <leitao@debian.org>