net: skbuff.c cleanup

(skb->data - skb->head) can be changed by skb_headroom(skb)

Remove some uses of NET_SKBUFF_DATA_USES_OFFSET, using
(skb_end_pointer(skb) - skb->head) or
(skb_tail_pointer(skb) - skb->head) : compiler does the right thing,
and this is more readable for us ;)

(struct skb_shared_info *) casts in pskb_expand_head() to help memcpy()
to use aligned moves.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 15 insertions, 32 deletions

diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index e2535fb4985d..231dff0dde2e 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -685,16 +685,10 @@ static void copy_skb_header(struct sk_buff *new, const struct sk_buff *old)
 
 struct sk_buff *skb_copy(const struct sk_buff *skb, gfp_t gfp_mask)
 {
-        int headerlen = skb->data - skb->head;
-        /*
-         *      Allocate the copy buffer
-         */
-        struct sk_buff *n;
-#ifdef NET_SKBUFF_DATA_USES_OFFSET
-        n = alloc_skb(skb->end + skb->data_len, gfp_mask);
-#else
-        n = alloc_skb(skb->end - skb->head + skb->data_len, gfp_mask);
-#endif
+        int headerlen = skb_headroom(skb);
+        unsigned int size = (skb_end_pointer(skb) - skb->head) + skb->data_len;
+        struct sk_buff *n = alloc_skb(size, gfp_mask);
+
         if (!n)
                 return NULL;
 
@@ -726,20 +720,14 @@ EXPORT_SYMBOL(skb_copy);
 
 struct sk_buff *pskb_copy(struct sk_buff *skb, gfp_t gfp_mask)
 {
-        /*
-         *      Allocate the copy buffer
-         */
-        struct sk_buff *n;
-#ifdef NET_SKBUFF_DATA_USES_OFFSET
-        n = alloc_skb(skb->end, gfp_mask);
-#else
-        n = alloc_skb(skb->end - skb->head, gfp_mask);
-#endif
+        unsigned int size = skb_end_pointer(skb) - skb->head;
+        struct sk_buff *n = alloc_skb(size, gfp_mask);
+
         if (!n)
                 goto out;
 
         /* Set the data pointer */
-        skb_reserve(n, skb->data - skb->head);
+        skb_reserve(n, skb_headroom(skb));
         /* Set the tail pointer and length */
         skb_put(n, skb_headlen(skb));
         /* Copy the bytes */
@@ -791,11 +779,7 @@ int pskb_expand_head(struct sk_buff *skb, int nhead, int ntail,
 {
         int i;
         u8 *data;
-#ifdef NET_SKBUFF_DATA_USES_OFFSET
-        int size = nhead + skb->end + ntail;
-#else
-        int size = nhead + (skb->end - skb->head) + ntail;
-#endif
+        int size = nhead + (skb_end_pointer(skb) - skb->head) + ntail;
         long off;
 
         BUG_ON(nhead < 0);
@@ -810,13 +794,12 @@ int pskb_expand_head(struct sk_buff *skb, int nhead, int ntail,
                 goto nodata;
 
         /* Copy only real data... and, alas, header. This should be
-         * optimized for the cases when header is void. */
-#ifdef NET_SKBUFF_DATA_USES_OFFSET
-        memcpy(data + nhead, skb->head, skb->tail);
-#else
-        memcpy(data + nhead, skb->head, skb->tail - skb->head);
-#endif
-        memcpy(data + size, skb_end_pointer(skb),
+         * optimized for the cases when header is void.
+         */
+        memcpy(data + nhead, skb->head, skb_tail_pointer(skb) - skb->head);
+
+        memcpy((struct skb_shared_info *)(data + size),
+               skb_shinfo(skb),
                offsetof(struct skb_shared_info, frags[skb_shinfo(skb)->nr_frags]));
 
         for (i = 0; i < skb_shinfo(skb)->nr_frags; i++)