net: remove skb recycling

[ Upstream commits acb600def2110b1310466c0e485c0d26299898ae
  and 66eef59f22275002f621ff9d951886b513d011b3. ]

Over time, skb recycling infrastructure got litle interest and
many bugs. Generic rx path skb allocation is now using page
fragments for efficient GRO / TCP coalescing, and recyling
a tx skb for rx path is not worth the pain.

Last identified bug is that fat skbs can be recycled
and it can endup using high order pages after few iterations.

With help from Maxime Bizon, who pointed out that commit
87151b8689d (net: allow pskb_expand_head() to get maximum tailroom)
introduced this regression for recycled skbs.

Instead of fixing this bug, lets remove skb recycling.

Drivers wanting really hot skbs should use build_skb() anyway,
to allocate/populate sk_buff right before netif_receive_skb()

Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Maxime Bizon <mbizon@freebox.fr>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 0 insertions, 47 deletions

diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index e33ebae519c8..ef172afd3a8b 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -641,53 +641,6 @@ 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
- *
- *	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().
- */
-bool skb_recycle_check(struct sk_buff *skb, int skb_size)
-{
-	if (!skb_is_recycleable(skb, skb_size))
-		return false;
-
-	skb_recycle(skb);
-
-	return true;
-}
-EXPORT_SYMBOL(skb_recycle_check);
-
 static void __copy_skb_header(struct sk_buff *new, const struct sk_buff *old)
 {
 	new->tstamp		= old->tstamp;