net: add documentation for skb recycling

Commit 04a4bb55bcf35b63d40fd2725e58599ff8310dd7 ("net: add
skb_recycle_check() to enable netdriver skb recycling") added a
method for network drivers to recycle skbuffs, but while use of
this mechanism was documented in the commit message, it should
really have been added as a docbook comment as well -- this
patch does that.

Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: Lennert Buytenhek <buytenh@marvell.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 12 insertions, 0 deletions

diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 4e22e3a35359..ebb6b94f8af2 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -449,6 +449,18 @@ void kfree_skb(struct sk_buff *skb)
         __kfree_skb(skb);
 }
 
+/**
+ *      skb_recycle_check - check if skb can be reused for receive
+ *      @skb: buffer
+ *      @skb_size: minimum receive buffer size
+ *
+ *      Checks that the skb passed in is not shared or cloned, and
+ *      that it is linear and its head portion at least as large as
+ *      skb_size so that it can be recycled as a receive buffer.
+ *      If these conditions are met, this function does any necessary
+ *      reference count dropping and cleans up the skbuff as if it
+ *      just came from __alloc_skb().
+ */
 int skb_recycle_check(struct sk_buff *skb, int skb_size)
 {
         struct skb_shared_info *shinfo;