[PATCH net-next 0/3] net: use IP_OUTNOROUTES drop reason

[PATCH net-next 0/3] net: use IP_OUTNOROUTES drop reason

[Eric Dumazet]

First patch changes sk_skb_reason_drop() sock to be const.

Second and last patch add SKB_DROP_REASON_IP_OUTNOROUTES
to both tcp_v6_send_response() and inet6_csk_xmit().

Eric Dumazet (3):
  net: constify sk_skb_reason_drop() sock parameter
  tcp: use SKB_DROP_REASON_IP_OUTNOROUTES in tcp_v6_send_response()
  ipv6: use SKB_DROP_REASON_IP_OUTNOROUTES in inet6_csk_xmit()

 include/linux/skbuff.h           | 3 ++-
 include/trace/events/skb.h       | 4 ++--
 net/core/skbuff.c                | 5 +++--
 net/ipv6/inet6_connection_sock.c | 3 ++-
 net/ipv6/tcp_ipv6.c              | 2 +-
 5 files changed, 10 insertions(+), 7 deletions(-)

-- 
2.54.0.563.g4f69b47b94-goog

[PATCH net-next 1/3] net: constify sk_skb_reason_drop() sock parameter

[Eric Dumazet]

sk_skb_reason_drop() does not change sock parameter, make it
const so that we can call it from TCP stack without a cast
on a (const) listener socket.

Signed-off-by: Eric Dumazet <edumazet@google.com>
---
 include/linux/skbuff.h     | 3 ++-
 include/trace/events/skb.h | 4 ++--
 net/core/skbuff.c          | 5 +++--
 3 files changed, 7 insertions(+), 5 deletions(-)

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 2bcf78a4de7b9edb0d1342319d4340c0a9997eeb..746e741a8ef99b3052ad581650e5d0db2a95dbb3 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -1313,7 +1313,8 @@ static inline bool skb_data_unref(const struct sk_buff *skb,
 	return true;
 }
 
-void __fix_address sk_skb_reason_drop(struct sock *sk, struct sk_buff *skb,
+void __fix_address sk_skb_reason_drop(const struct sock *sk,
+				      struct sk_buff *skb,
 				      enum skb_drop_reason reason);
 
 static inline void
diff --git a/include/trace/events/skb.h b/include/trace/events/skb.h
index b877133cd93a80f6b130fab64f334ecdeab8c8fd..2945aa7fe9a7ded5bdec5be3a67382de95239517 100644
--- a/include/trace/events/skb.h
+++ b/include/trace/events/skb.h
@@ -24,14 +24,14 @@ DEFINE_DROP_REASON(FN, FN)
 TRACE_EVENT(kfree_skb,
 
 	TP_PROTO(struct sk_buff *skb, void *location,
-		 enum skb_drop_reason reason, struct sock *rx_sk),
+		 enum skb_drop_reason reason, const struct sock *rx_sk),
 
 	TP_ARGS(skb, location, reason, rx_sk),
 
 	TP_STRUCT__entry(
 		__field(void *,		skbaddr)
 		__field(void *,		location)
-		__field(void *,		rx_sk)
+		__field(const void *,	rx_sk)
 		__field(unsigned short,	protocol)
 		__field(enum skb_drop_reason,	reason)
 	),
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 7dad68e3b5186cf622a3ed5a6e87c09d46bc3fd6..acca1365672c4f98b004c2548133d70c9cf5ddc1 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -1206,7 +1206,7 @@ void __kfree_skb(struct sk_buff *skb)
 EXPORT_SYMBOL(__kfree_skb);
 
 static __always_inline
-bool __sk_skb_reason_drop(struct sock *sk, struct sk_buff *skb,
+bool __sk_skb_reason_drop(const struct sock *sk, struct sk_buff *skb,
 			  enum skb_drop_reason reason)
 {
 	if (unlikely(!skb_unref(skb)))
@@ -1235,7 +1235,8 @@ bool __sk_skb_reason_drop(struct sock *sk, struct sk_buff *skb,
  *	'kfree_skb' tracepoint.
  */
 void __fix_address
-sk_skb_reason_drop(struct sock *sk, struct sk_buff *skb, enum skb_drop_reason reason)
+sk_skb_reason_drop(const struct sock *sk, struct sk_buff *skb,
+		   enum skb_drop_reason reason)
 {
 	if (__sk_skb_reason_drop(sk, skb, reason))
 		__kfree_skb(skb);
-- 
2.54.0.563.g4f69b47b94-goog

Re: [PATCH net-next 1/3] net: constify sk_skb_reason_drop() sock parameter

[David Ahern]

On 5/7/26 2:43 AM, Eric Dumazet wrote:
> sk_skb_reason_drop() does not change sock parameter, make it
> const so that we can call it from TCP stack without a cast
> on a (const) listener socket.
> 
> Signed-off-by: Eric Dumazet <edumazet@google.com>
> ---
>  include/linux/skbuff.h     | 3 ++-
>  include/trace/events/skb.h | 4 ++--
>  net/core/skbuff.c          | 5 +++--
>  3 files changed, 7 insertions(+), 5 deletions(-)
> 
>

Reviewed-by: David Ahern <dsahern@kernel.org>

Re: [PATCH net-next 1/3] net: constify sk_skb_reason_drop() sock parameter

[Kuniyuki Iwashima]

On Thu, May 7, 2026 at 1:43 AM Eric Dumazet <edumazet@google.com> wrote:
>
> sk_skb_reason_drop() does not change sock parameter, make it
> const so that we can call it from TCP stack without a cast
> on a (const) listener socket.
>
> Signed-off-by: Eric Dumazet <edumazet@google.com>

Reviewed-by: Kuniyuki Iwashima <kuniyu@google.com>

Re: [PATCH net-next 1/3] net: constify sk_skb_reason_drop() sock parameter

[Jakub Kicinski]

On Thu,  7 May 2026 08:43:03 +0000 Eric Dumazet wrote:
>  	TP_PROTO(struct sk_buff *skb, void *location,
> -		 enum skb_drop_reason reason, struct sock *rx_sk),
> +		 enum skb_drop_reason reason, const struct sock *rx_sk),

build says drop_monitor registers for this tracepoint from within 
the kernel, and needs adjusting.

Re: [PATCH net-next 1/3] net: constify sk_skb_reason_drop() sock parameter

[Eric Dumazet]

On Fri, May 8, 2026 at 3:15 PM Jakub Kicinski <kuba@kernel.org> wrote:
>
> On Thu,  7 May 2026 08:43:03 +0000 Eric Dumazet wrote:
> >       TP_PROTO(struct sk_buff *skb, void *location,
> > -              enum skb_drop_reason reason, struct sock *rx_sk),
> > +              enum skb_drop_reason reason, const struct sock *rx_sk),
>
> build says drop_monitor registers for this tracepoint from within
> the kernel, and needs adjusting.

Thanks, I fixed this in V2.

[PATCH net-next 2/3] tcp: use SKB_DROP_REASON_IP_OUTNOROUTES in tcp_v6_send_response()

[Eric Dumazet]

Replace a bare kfree_skb() with a modern sk_skb_reason_drop() call,
and provide IP_OUTNOROUTES drop reason.

Signed-off-by: Eric Dumazet <edumazet@google.com>
---
 net/ipv6/tcp_ipv6.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index 2c3f7a739709d7b89f376f79b71173e5f2d8e64e..3574b2c28a55182d46657cfcca528a0ac0de99b7 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -980,7 +980,7 @@ static void tcp_v6_send_response(const struct sock *sk, struct sk_buff *skb, u32
 		return;
 	}
 
-	kfree_skb(buff);
+	sk_skb_reason_drop(sk, buff, SKB_DROP_REASON_IP_OUTNOROUTES);
 }
 
 static void tcp_v6_send_reset(const struct sock *sk, struct sk_buff *skb,
-- 
2.54.0.563.g4f69b47b94-goog

Re: [PATCH net-next 2/3] tcp: use SKB_DROP_REASON_IP_OUTNOROUTES in tcp_v6_send_response()

[David Ahern]

On 5/7/26 2:43 AM, Eric Dumazet wrote:
> Replace a bare kfree_skb() with a modern sk_skb_reason_drop() call,
> and provide IP_OUTNOROUTES drop reason.
> 
> Signed-off-by: Eric Dumazet <edumazet@google.com>
> ---
>  net/ipv6/tcp_ipv6.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 


Reviewed-by: David Ahern <dsahern@kernel.org>

Re: [PATCH net-next 2/3] tcp: use SKB_DROP_REASON_IP_OUTNOROUTES in tcp_v6_send_response()

[Kuniyuki Iwashima]

On Thu, May 7, 2026 at 1:43 AM Eric Dumazet <edumazet@google.com> wrote:
>
> Replace a bare kfree_skb() with a modern sk_skb_reason_drop() call,
> and provide IP_OUTNOROUTES drop reason.
>
> Signed-off-by: Eric Dumazet <edumazet@google.com>

Reviewed-by: Kuniyuki Iwashima <kuniyu@google.com>

[PATCH net-next 3/3] ipv6: use SKB_DROP_REASON_IP_OUTNOROUTES in inet6_csk_xmit()

[Eric Dumazet]

Replace a bare kfree_skb() with a modern sk_skb_reason_drop() call,
and provide IP_OUTNOROUTES drop reason.

Signed-off-by: Eric Dumazet <edumazet@google.com>
---
 net/ipv6/inet6_connection_sock.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/ipv6/inet6_connection_sock.c b/net/ipv6/inet6_connection_sock.c
index 37534e1168992c44e1400dacab87e79d04c64a41..4665d84a7380d90b7d180a429017f577fcb6936a 100644
--- a/net/ipv6/inet6_connection_sock.c
+++ b/net/ipv6/inet6_connection_sock.c
@@ -102,7 +102,8 @@ int inet6_csk_xmit(struct sock *sk, struct sk_buff *skb, struct flowi *fl_unused
 		if (IS_ERR(dst)) {
 			WRITE_ONCE(sk->sk_err_soft, -PTR_ERR(dst));
 			sk->sk_route_caps = 0;
-			kfree_skb(skb);
+			sk_skb_reason_drop(sk, skb,
+					   SKB_DROP_REASON_IP_OUTNOROUTES);
 			return PTR_ERR(dst);
 		}
 		/* Restore final destination back after routing done */
-- 
2.54.0.563.g4f69b47b94-goog

Re: [PATCH net-next 3/3] ipv6: use SKB_DROP_REASON_IP_OUTNOROUTES in inet6_csk_xmit()

[David Ahern]

On 5/7/26 2:43 AM, Eric Dumazet wrote:
> Replace a bare kfree_skb() with a modern sk_skb_reason_drop() call,
> and provide IP_OUTNOROUTES drop reason.
> 
> Signed-off-by: Eric Dumazet <edumazet@google.com>
> ---
>  net/ipv6/inet6_connection_sock.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 

Reviewed-by: David Ahern <dsahern@kernel.org>

Re: [PATCH net-next 3/3] ipv6: use SKB_DROP_REASON_IP_OUTNOROUTES in inet6_csk_xmit()

[Kuniyuki Iwashima]

On Thu, May 7, 2026 at 1:43 AM Eric Dumazet <edumazet@google.com> wrote:
>
> Replace a bare kfree_skb() with a modern sk_skb_reason_drop() call,
> and provide IP_OUTNOROUTES drop reason.
>
> Signed-off-by: Eric Dumazet <edumazet@google.com>

Reviewed-by: Kuniyuki Iwashima <kuniyu@google.com>

Re: [PATCH net-next 0/3] net: use IP_OUTNOROUTES drop reason

[Eric Dumazet]

On Thu, May 7, 2026 at 1:43 AM Eric Dumazet <edumazet@google.com> wrote:
>
> First patch changes sk_skb_reason_drop() sock to be const.
>
> Second and last patch add SKB_DROP_REASON_IP_OUTNOROUTES
> to both tcp_v6_send_response() and inet6_csk_xmit().
>
> Eric Dumazet (3):
>   net: constify sk_skb_reason_drop() sock parameter
>   tcp: use SKB_DROP_REASON_IP_OUTNOROUTES in tcp_v6_send_response()
>   ipv6: use SKB_DROP_REASON_IP_OUTNOROUTES in inet6_csk_xmit()
>
>  include/linux/skbuff.h           | 3 ++-
>  include/trace/events/skb.h       | 4 ++--
>  net/core/skbuff.c                | 5 +++--
>  net/ipv6/inet6_connection_sock.c | 3 ++-
>  net/ipv6/tcp_ipv6.c              | 2 +-
>  5 files changed, 10 insertions(+), 7 deletions(-)

I will send a V2 today, changes to net/core/drop_monitor.c were missed.

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