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>

1 files changed, 8 insertions, 14 deletions

diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 4d085d454285..17e4b1e1bf2c 100644
--- 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;