net: Allow skb_recycle_check to be done in stages

skb_recycle_check resets the skb if it's eligible for recycling.
However, there are times when a driver might want to optionally
manipulate the skb data with the skb before resetting the skb,
but after it has determined eligibility.  We do this by splitting the
eligibility check from the skb reset, creating two inline functions to
accomplish that task.

Signed-off-by: Andy Fleming <afleming@freescale.com>
Acked-by: David Daney <david.daney@cavium.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 26 insertions, 25 deletions

diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index ce357d986251..e27104039a39 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -485,6 +485,30 @@ void consume_skb(struct sk_buff *skb)
 EXPORT_SYMBOL(consume_skb);
 
 /**
+ *      skb_recycle - clean up an skb for reuse
+ *      @skb: buffer
+ *
+ *      Recycles the skb to be reused as a receive buffer. This
+ *      function does any necessary reference count dropping, and
+ *      cleans up the skbuff as if it just came from __alloc_skb().
+ */
+void skb_recycle(struct sk_buff *skb)
+{
+        struct skb_shared_info *shinfo;
+
+        skb_release_head_state(skb);
+
+        shinfo = skb_shinfo(skb);
+        memset(shinfo, 0, offsetof(struct skb_shared_info, dataref));
+        atomic_set(&shinfo->dataref, 1);
+
+        memset(skb, 0, offsetof(struct sk_buff, tail));
+        skb->data = skb->head + NET_SKB_PAD;
+        skb_reset_tail_pointer(skb);
+}
+EXPORT_SYMBOL(skb_recycle);
+
+/**
  *      skb_recycle_check - check if skb can be reused for receive
  *      @skb: buffer
  *      @skb_size: minimum receive buffer size
@@ -498,33 +522,10 @@ EXPORT_SYMBOL(consume_skb);
  */
 bool skb_recycle_check(struct sk_buff *skb, int skb_size)
 {
-        struct skb_shared_info *shinfo;
-
-        if (irqs_disabled())
-                return false;
-
-        if (skb_shinfo(skb)->tx_flags & SKBTX_DEV_ZEROCOPY)
-                return false;
-
-        if (skb_is_nonlinear(skb) || skb->fclone != SKB_FCLONE_UNAVAILABLE)
-                return false;
-
-        skb_size = SKB_DATA_ALIGN(skb_size + NET_SKB_PAD);
-        if (skb_end_pointer(skb) - skb->head < skb_size)
-                return false;
-
-        if (skb_shared(skb) || skb_cloned(skb))
+        if (!skb_is_recycleable(skb, skb_size))
                 return false;
 
-        skb_release_head_state(skb);
-
-        shinfo = skb_shinfo(skb);
-        memset(shinfo, 0, offsetof(struct skb_shared_info, dataref));
-        atomic_set(&shinfo->dataref, 1);
-
-        memset(skb, 0, offsetof(struct sk_buff, tail));
-        skb->data = skb->head + NET_SKB_PAD;
-        skb_reset_tail_pointer(skb);
+        skb_recycle(skb);
 
         return true;
 }