From: Josh Don <joshdon@google.com>
To: Willem de Bruijn <willemdebruijn.kernel@gmail.com>,
"David S. Miller" <davem@davemloft.net>,
Eric Dumazet <edumazet@kernel.org>,
Jakub Kicinski <kuba@kernel.org>,
Paolo Abeni <pabeni@redhat.com>
Cc: Simon Horman <horms@kernel.org>,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
Josh Don <joshdon@google.com>
Subject: [PATCH] udp: Add noinline_for_tracing annotation for udp{,_v6}_send_skb()
Date: Mon, 19 Oct 2026 23:07:58 +0000 [thread overview]
Message-ID: <20261019230758.2960779-1-joshdon@google.com> (raw)
We hook udp_send_skb() and udp_v6_send_skb() using BPF fentry programs
to monitor UDP transmits. Both functions are static and have two
callers: udp{,v6}_sendmsg() and udp{,_v6}_push_pending_frames().
After an FDO profile update, udp_v6_send_skb() is now inlined into
udpv6_sendmsg(), while an out-of-line copy remains for
udp_v6_push_pending_frames(). The fentry program still attaches
successfully, but it is silently bypassed for all uncorked sends.
To address this, make both functions noinline explicitly for tracing,
as was done for tcp_drop_reason() in commit dbd5e2e79ed8 ("net: tcp:
Add noinline_for_tracing annotation for tcp_drop_reason()").
Assisted-by: LLM
Signed-off-by: Josh Don <joshdon@google.com>
---
net/ipv4/udp.c | 4 ++--
net/ipv6/udp.c | 4 ++--
2 files changed, 4 insertions(+), 4 deletions(-)
diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index b090bd1f59e86..487c8cc8ab206 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -1110,8 +1110,8 @@ void udp_set_csum(bool nocheck, struct sk_buff *skb,
}
EXPORT_SYMBOL(udp_set_csum);
-static int udp_send_skb(struct sk_buff *skb, struct flowi4 *fl4,
- struct inet_cork *cork)
+noinline_for_tracing static int
+udp_send_skb(struct sk_buff *skb, struct flowi4 *fl4, struct inet_cork *cork)
{
struct sock *sk = skb->sk;
int offset, len, datalen;
diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
index 93478d1ad5769..fe92538835176 100644
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -1366,8 +1366,8 @@ static void udp6_hwcsum_outgoing(struct sock *sk, struct sk_buff *skb,
* Sending
*/
-static int udp_v6_send_skb(struct sk_buff *skb, struct flowi6 *fl6,
- struct inet_cork *cork)
+noinline_for_tracing static int
+udp_v6_send_skb(struct sk_buff *skb, struct flowi6 *fl6, struct inet_cork *cork)
{
struct sock *sk = skb->sk;
int offset, len, datalen;
--
2.56.0.212.g129ede20d9-goog
next reply other threads:[~2026-10-19 23:08 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-10-19 23:07 Josh Don [this message]
2026-10-19 23:39 ` Willem de Bruijn
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