netdev - [PATCH RFC 2/6] skbuff: add an api to orphan frags

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Date:	Mon, 7 May 2012 16:54:37 +0300
From:	"Michael S. Tsirkin" <mst@...hat.com>
To:	Ian Campbell <Ian.Campbell@...rix.com>
Cc:	David Miller <davem@...emloft.net>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	"eric.dumazet@...il.com" <eric.dumazet@...il.com>
Subject: [PATCH RFC 2/6] skbuff: add an api to orphan frags

Many places do
       if ((skb_shinfo(skb)->tx_flags & SKBTX_DEV_ZEROCOPY))
		skb_copy_ubufs(skb, gfp_mask);
to copy and invoke frag destructors if necessary.
Add an inline helper for this.

Signed-off-by: Michael S. Tsirkin <mst@...hat.com>
---
 include/linux/skbuff.h |   24 ++++++++++++++++++++++++
 1 files changed, 24 insertions(+), 0 deletions(-)

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index bb78f70..28d842e 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -1711,6 +1711,30 @@ static inline void skb_orphan(struct sk_buff *skb)
 }
 
 /**
+ *	skb_orphan_frags - orphan the frags contained in a buffer
+ *	@skb: buffer to orphan frags from
+ *	@gfp_mask: allocation mask for replacement pages
+ *
+ *	For each frag in the SKB which needs a destructor (i.e. has an
+ *	owner) create a copy of that frag and release the original
+ *	page by calling the destructor.
+ */
+static inline int skb_orphan_frags(struct sk_buff *skb, gfp_t gfp_mask)
+{
+	if (likely(!(skb_shinfo(skb)->tx_flags & SKBTX_DEV_ZEROCOPY)))
+		return 0;
+	return skb_copy_ubufs(skb, gfp_mask);
+}
+
+
+static inline void skb_copy_frag_destructor(struct sk_buff *to,
+					    struct sk_buff *from)
+{
+	skb_shinfo(to)->tx_flags |= skb_shinfo(from)->tx_flags &
+		SKBTX_DEV_ZEROCOPY;
+}
+
+/**
  *	__skb_queue_purge - empty a list
  *	@list: list to empty
  *
-- 
MST

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