[RFC net-next v2 01/18] lwtunnel: track callback dispatch separately from return value
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From: Ralf Lici <ralf@mandelbit.com>
Date: 2026-10-24 09:26:11
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lkml
Subsystem:
networking [general], networking [ipv4/ipv6], the rest · Maintainers:
"David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, David Ahern, Ido Schimmel, Linus Torvalds
LWT used -EOPNOTSUPP both as its missing-callback sentinel and as a valid callback error. Track whether an operation was invoked separately so callbacks can return meaningful errors without triggering the no-operation skb cleanup path. Signed-off-by: Ralf Lici <ralf@mandelbit.com> --- New patch in RFC v2. net/core/lwtunnel.c | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-)
diff --git a/net/core/lwtunnel.c b/net/core/lwtunnel.c
index 8223c44f10c8..db21b9ff6f86 100644
--- a/net/core/lwtunnel.c
+++ b/net/core/lwtunnel.c@@ -322,6 +322,7 @@ int lwtunnel_output(struct net *net, struct sock *sk, struct sk_buff *skb) { const struct lwtunnel_encap_ops *ops; struct lwtunnel_state *lwtstate; + bool called_cb = false; struct dst_entry *dst; int ret;
@@ -353,13 +354,14 @@ int lwtunnel_output(struct net *net, struct sock *sk, struct sk_buff *skb) if (likely(ops && ops->output)) { /* Encap pushes outer headers over the metadata; drop it. */ skb_metadata_clear(skb); + called_cb = true; dev_xmit_recursion_inc(); ret = ops->output(net, sk, skb); dev_xmit_recursion_dec(); } rcu_read_unlock(); - if (ret == -EOPNOTSUPP) + if (unlikely(!called_cb)) goto drop; goto out;
@@ -377,6 +379,7 @@ int lwtunnel_xmit(struct sk_buff *skb) { const struct lwtunnel_encap_ops *ops; struct lwtunnel_state *lwtstate; + bool called_cb = false; struct dst_entry *dst; int ret;
@@ -409,13 +412,14 @@ int lwtunnel_xmit(struct sk_buff *skb) if (likely(ops && ops->xmit)) { /* Encap pushes outer headers over the metadata; drop it. */ skb_metadata_clear(skb); + called_cb = true; dev_xmit_recursion_inc(); ret = ops->xmit(skb); dev_xmit_recursion_dec(); } rcu_read_unlock(); - if (ret == -EOPNOTSUPP) + if (unlikely(!called_cb)) goto drop; goto out;
@@ -433,6 +437,7 @@ int lwtunnel_input(struct sk_buff *skb) { const struct lwtunnel_encap_ops *ops; struct lwtunnel_state *lwtstate; + bool called_cb = false; struct dst_entry *dst; int ret;
@@ -462,13 +467,14 @@ int lwtunnel_input(struct sk_buff *skb) if (likely(ops && ops->input)) { /* Encap pushes outer headers over the metadata; drop it. */ skb_metadata_clear(skb); + called_cb = true; dev_xmit_recursion_inc(); ret = ops->input(skb); dev_xmit_recursion_dec(); } rcu_read_unlock(); - if (ret == -EOPNOTSUPP) + if (unlikely(!called_cb)) goto drop; return ret;
--
2.55.0