net: add missing documentation in linux/skbuff.h

This patch adds missing documentation for some inline functions on
linux/skbuff.h. The patch is incomplete and a lot more can be added,
just wondering if it's of interest of the netdev developers.

Also fixed some whitespaces.
Signed-off-by: Pedro Tammela <pctammela@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/skbuff.h

@@ -327,26 +327,49 @@ struct skb_frag_struct {
 #endif
 };
 
+/**
+ * skb_frag_size - Returns the size of a skb fragment
+ * @frag: skb fragment
+ */
 static inline unsigned int skb_frag_size(const skb_frag_t *frag)
 {
 	return frag->size;
 }
 
+/**
+ * skb_frag_size_set - Sets the size of a skb fragment
+ * @frag: skb fragment
+ * @size: size of fragment
+ */
 static inline void skb_frag_size_set(skb_frag_t *frag, unsigned int size)
 {
 	frag->size = size;
 }
 
+/**
+ * skb_frag_size_add - Incrementes the size of a skb fragment by %delta
+ * @frag: skb fragment
+ * @delta: value to add
+ */
 static inline void skb_frag_size_add(skb_frag_t *frag, int delta)
 {
 	frag->size += delta;
 }
 
+/**
+ * skb_frag_size_sub - Decrements the size of a skb fragment by %delta
+ * @frag: skb fragment
+ * @delta: value to subtract
+ */
 static inline void skb_frag_size_sub(skb_frag_t *frag, int delta)
 {
 	frag->size -= delta;
 }
 
+/**
+ * skb_frag_must_loop - Test if %p is a high memory page
+ * @p: fragment's page
+ */
 static inline bool skb_frag_must_loop(struct page *p)
 {
 #if defined(CONFIG_HIGHMEM)
@@ -883,7 +906,10 @@ struct sk_buff {
 #define SKB_ALLOC_RX		0x02
 #define SKB_ALLOC_NAPI		0x04
 
-/* Returns true if the skb was allocated from PFMEMALLOC reserves */
+/**
+ * skb_pfmemalloc - Test if the skb was allocated from PFMEMALLOC reserves
+ * @skb: buffer
+ */
 static inline bool skb_pfmemalloc(const struct sk_buff *skb)
 {
 	return unlikely(skb->pfmemalloc);
@@ -952,6 +978,10 @@ static inline bool skb_dst_is_noref(const struct sk_buff *skb)
 	return (skb->_skb_refdst & SKB_DST_NOREF) && skb_dst(skb);
 }
 
+/**
+ * skb_rtable - Returns the skb &rtable
+ * @skb: buffer
+ */
 static inline struct rtable *skb_rtable(const struct sk_buff *skb)
 {
 	return (struct rtable *)skb_dst(skb);
@@ -966,6 +996,10 @@ static inline bool skb_pkt_type_ok(u32 ptype)
 	return ptype <= PACKET_OTHERHOST;
 }
 
+/**
+ * skb_napi_id - Returns the skb's NAPI id
+ * @skb: buffer
+ */
 static inline unsigned int skb_napi_id(const struct sk_buff *skb)
 {
 #ifdef CONFIG_NET_RX_BUSY_POLL
@@ -975,7 +1009,12 @@ static inline unsigned int skb_napi_id(const struct sk_buff *skb)
 #endif
 }
 
-/* decrement the reference count and return true if we can free the skb */
+/**
+ * skb_unref - decrement the skb's reference count
+ * @skb: buffer
+ *
+ * Returns true if we can free the skb.
+ */
 static inline bool skb_unref(struct sk_buff *skb)
 {
 	if (unlikely(!skb))
@@ -1005,6 +1044,14 @@ struct sk_buff *__alloc_skb(unsigned int size, gfp_t priority, int flags,
 			    int node);
 struct sk_buff *__build_skb(void *data, unsigned int frag_size);
 struct sk_buff *build_skb(void *data, unsigned int frag_size);
+
+/**
+ * alloc_skb - allocate a network buffer
+ * @size: size to allocate
+ * @priority: allocation mask
+ *
+ * This function is a convenient wrapper around __alloc_skb().
+ */
 static inline struct sk_buff *alloc_skb(unsigned int size,
 					gfp_t priority)
 {
@@ -1047,6 +1094,13 @@ static inline bool skb_fclone_busy(const struct sock *sk,
 	       fclones->skb2.sk == sk;
 }
 
+/**
+ * alloc_skb_fclone - allocate a network buffer from fclone cache
+ * @size: size to allocate
+ * @priority: allocation mask
+ *
+ * This function is a convenient wrapper around __alloc_skb().
+ */
 static inline struct sk_buff *alloc_skb_fclone(unsigned int size,
 					       gfp_t priority)
 {