On Mon, 11 Dec 2018, Florian Westphal wrote:
...
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index b1831a5ca173..d715736eb734 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
...
@@ -3896,6 +3906,113 @@ static inline void nf_conntrack_get(struct nf_conntrack
*nfct)
atomic_inc(&nfct->use);
}
#endif
+
+#ifdef CONFIG_SKB_EXTENSIONS
+enum skb_ext_id {
+#if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
+ SKB_EXT_BRIDGE_NF,
+#endif
+ SKB_EXT_NUM, /* must be last */
+};
Could enum skb_ext_id always be defined, with none of the SKB_EXT_* values
conditionally excluded? In combination with some alternate function
definitions below (see later comments) I think this could reduce the need
for CONFIG_SKB_EXTENSIONS preprocessor conditionals throughout the net
code.
+
+/**
+ * struct skb_ext - sk_buff extensions
+ * @refcnt: 1 on allocation, deallocated on 0
+ * @offset: offset to add to @data to obtain extension address
+ * @chunks: size currently allocated, stored in SKB_EXT_ALIGN_SHIFT units
+ * @data: start of extension data, variable sized
+ *
+ * Note: offsets/lengths are stored in chunks of 8 bytes, this allows
+ * to use 'u8' types while allowing up to 2kb worth of extension data.
+ */
+struct skb_ext {
+ refcount_t refcnt;
+ u8 offset[SKB_EXT_NUM]; /* in chunks of 8 bytes */
+ u8 chunks; /* same */
+ char data[0] __aligned(8);
+};
+
+void *skb_ext_add(struct sk_buff *skb, enum skb_ext_id id);
+void __skb_ext_del(struct sk_buff *skb, enum skb_ext_id id);
+void __skb_ext_free(struct skb_ext *ext);
+
+static inline void __skb_ext_put(struct skb_ext *ext)
+{
+ if (ext && refcount_dec_and_test(&ext->refcnt))
+ __skb_ext_free(ext);
+}
+
+static inline void skb_ext_put(struct sk_buff *skb)
+{
+ if (skb->active_extensions)
+ __skb_ext_put(skb->extensions);
+}
+
+static inline void skb_ext_get(struct sk_buff *skb)
+{
+ if (skb->active_extensions) {
+ struct skb_ext *ext = skb->extensions;
+
+ if (ext)
+ refcount_inc(&ext->refcnt);
+ }
+}
+
+static inline void __skb_ext_copy(struct sk_buff *dst,
+ const struct sk_buff *src)
+{
+ dst->active_extensions = src->active_extensions;
+
+ if (src->active_extensions) {
+ struct skb_ext *ext = src->extensions;
+
+ if (ext)
+ refcount_inc(&ext->refcnt);
+ dst->extensions = ext;
+ }
+}
+
+static inline void skb_ext_copy(struct sk_buff *dst, const struct sk_buff *src)
+{
+ skb_ext_put(dst);
+ __skb_ext_copy(dst, src);
+}
+
+static inline bool __skb_ext_exist(const struct skb_ext *ext, enum skb_ext_id
i)
+{
+ return !!ext->offset[i];
+}
+
+static inline bool skb_ext_exist(const struct sk_buff *skb, enum skb_ext_id id)
+{
+ return skb->active_extensions & (1 << id);
+}
+
+static inline void skb_ext_del(struct sk_buff *skb, enum skb_ext_id id)
+{
+ if (skb_ext_exist(skb, id))
+ __skb_ext_del(skb, id);
+}
+
+static inline void *skb_ext_find(const struct sk_buff *skb, enum skb_ext_id id)
+{
+ if (skb_ext_exist(skb, id)) {
+ struct skb_ext *ext = skb->extensions;
+
+ if (ext && __skb_ext_exist(ext, id))
+ return (void *)ext + (ext->offset[id] << 3);
+ }
+
+ return NULL;
+}
+#else
+static inline void skb_ext_put(struct sk_buff *skb) {}
+static inline void skb_ext_get(struct sk_buff *skb) {}
+static inline void skb_ext_del(struct sk_buff *skb, int unused) {}
+static inline void __skb_ext_copy(struct sk_buff *d, const struct sk_buff *s)
{}
+static inline void skb_ext_copy(struct sk_buff *dst, const struct sk_buff *s)
{}
For the !CONFIG_SKB_EXTENSIONS case, an alternate definition of
skb_ext_exist() that always returns false would be useful to reduce the
need for preprocessor conditionals. A similar skb_ext_find() that always
returns NULL might also be helpful.
+#endif /* CONFIG_SKB_EXTENSIONS */
+
#if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
static inline void nf_bridge_put(struct nf_bridge_info *nf_bridge)
{
Thanks,
--
Mat Martineau
Intel OTC
