skb: Drop "fastpath" variable for skb_cloned check in pskb_expand_head

Since there is now only one spot that actually uses "fastpath" there isn't
much point in carrying it.  Instead we can just use a check for skb_cloned
to verify if we can perform the fast-path free for the head or not.

Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 4d085d4..17e4b1e 100644 (file)
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -932,7 +932,6 @@ int pskb_expand_head(struct sk_buff *skb, int nhead, int ntail,
        u8 *data;
        int size = nhead + (skb_end_pointer(skb) - skb->head) + ntail;
        long off;
-       bool fastpath;
 
        BUG_ON(nhead < 0);
 
@@ -941,16 +940,6 @@ int pskb_expand_head(struct sk_buff *skb, int nhead, int ntail,
 
        size = SKB_DATA_ALIGN(size);
 
-       /* Check if we can avoid taking references on fragments if we own
-        * the last reference on skb->head. (see skb_release_data())
-        */
-       if (!skb->cloned)
-               fastpath = true;
-       else {
-               int delta = skb->nohdr ? (1 << SKB_DATAREF_SHIFT) + 1 : 1;
-               fastpath = atomic_read(&skb_shinfo(skb)->dataref) == delta;
-       }
-
        data = kmalloc(size + SKB_DATA_ALIGN(sizeof(struct skb_shared_info)),
                       gfp_mask);
        if (!data)
@@ -966,9 +955,12 @@ int pskb_expand_head(struct sk_buff *skb, int nhead, int ntail,
               skb_shinfo(skb),
               offsetof(struct skb_shared_info, frags[skb_shinfo(skb)->nr_frags]));
 
-       if (fastpath) {
-               skb_free_head(skb);
-       } else {
+       /*
+        * if shinfo is shared we must drop the old head gracefully, but if it
+        * is not we can just drop the old head and let the existing refcount
+        * be since all we did is relocate the values
+        */
+       if (skb_cloned(skb)) {
                /* copy this zero copy skb frags */
                if (skb_shinfo(skb)->tx_flags & SKBTX_DEV_ZEROCOPY) {
                        if (skb_copy_ubufs(skb, gfp_mask))
@@ -981,6 +973,8 @@ int pskb_expand_head(struct sk_buff *skb, int nhead, int ntail,
                        skb_clone_fraglist(skb);
 
                skb_release_data(skb);
+       } else {
+               skb_free_head(skb);
        }
        off = (data + nhead) - skb->head;