@@ -139,9 +139,16 @@ struct sk_buff;
typedef struct skb_frag_struct skb_frag_t;
+struct skb_frag_destructor {
+ atomic_t ref;
+ int (*destroy)(void *data);
+ void *data;
+};
+
struct skb_frag_struct {
struct {
struct page *p;
+ struct skb_frag_destructor *destructor;
} page;
#if (BITS_PER_LONG > 32) || (PAGE_SIZE >= 65536)
__u32 page_offset;
@@ -1160,6 +1167,31 @@ static inline int skb_pagelen(const struct sk_buff *skb)
}
/**
+ * skb_frag_set_destructor - set destructor for a paged fragment
+ * @skb: buffer containing fragment to be initialised
+ * @i: paged fragment index to initialise
+ * @destroy: the destructor to use for this fragment
+ *
+ * Sets @destroy as the destructor to be called when all references to
+ * the frag @i in @skb (tracked over skb_clone, retransmit, pull-ups,
+ * etc) are released.
+ *
+ * When a destructor is set then reference counting is performed on
+ * @destroy->ref. When the ref reaches zero then @destroy->destroy
+ * will be called. The caller is responsible for holding and managing
+ * any other references (such a the struct page reference count).
+ *
+ * This function must be called before any use of skb_frag_ref() or
+ * skb_frag_unref().
+ */
+static inline void skb_frag_set_destructor(struct sk_buff *skb, int i,
+ struct skb_frag_destructor *destroy)
+{
+ skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
+ frag->page.destructor = destroy;
+}
+
+/**
* __skb_fill_page_desc - initialise a paged fragment in an skb
* @skb: buffer containing fragment to be initialised
* @i: paged fragment index to initialise
@@ -1178,6 +1210,7 @@ static inline void __skb_fill_page_desc(struct sk_buff *skb, int i,
skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
frag->page.p = page;
+ frag->page.destructor = NULL;
frag->page_offset = off;
skb_frag_size_set(frag, size);
}
@@ -1704,6 +1737,9 @@ static inline struct page *skb_frag_page(const skb_frag_t *frag)
return frag->page.p;
}
+extern void skb_frag_destructor_ref(struct skb_frag_destructor *destroy);
+extern void skb_frag_destructor_unref(struct skb_frag_destructor *destroy);
+
/**
* __skb_frag_ref - take an addition reference on a paged fragment.
* @frag: the paged fragment
@@ -1712,6 +1748,10 @@ static inline struct page *skb_frag_page(const skb_frag_t *frag)
*/
static inline void __skb_frag_ref(skb_frag_t *frag)
{
+ if (unlikely(frag->page.destructor)) {
+ skb_frag_destructor_ref(frag->page.destructor);
+ return;
+ }
get_page(skb_frag_page(frag));
}
@@ -1735,6 +1775,10 @@ static inline void skb_frag_ref(struct sk_buff *skb, int f)
*/
static inline void __skb_frag_unref(skb_frag_t *frag)
{
+ if (unlikely(frag->page.destructor)) {
+ skb_frag_destructor_unref(frag->page.destructor);
+ return;
+ }
put_page(skb_frag_page(frag));
}
@@ -303,6 +303,23 @@ struct sk_buff *dev_alloc_skb(unsigned int length)
}
EXPORT_SYMBOL(dev_alloc_skb);
+void skb_frag_destructor_ref(struct skb_frag_destructor *destroy)
+{
+ BUG_ON(destroy == NULL);
+ atomic_inc(&destroy->ref);
+}
+EXPORT_SYMBOL(skb_frag_destructor_ref);
+
+void skb_frag_destructor_unref(struct skb_frag_destructor *destroy)
+{
+ if (destroy == NULL)
+ return;
+
+ if (atomic_dec_and_test(&destroy->ref))
+ destroy->destroy(destroy->data);
+}
+EXPORT_SYMBOL(skb_frag_destructor_unref);
+
static void skb_drop_list(struct sk_buff **listp)
{
struct sk_buff *list = *listp;