linux-kernel - [PATCH 3.2 123/125] skbuff: add an api to orphan frags

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Message-ID: <lsq.1404846110.452209930@decadent.org.uk>
Date:	Tue, 08 Jul 2014 20:01:50 +0100
From:	Ben Hutchings <ben@...adent.org.uk>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:	akpm@...ux-foundation.org, "Michael S. Tsirkin" <mst@...hat.com>,
	"David S. Miller" <davem@...emloft.net>
Subject: [PATCH 3.2 123/125] skbuff: add an api to orphan frags

3.2.61-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: "Michael S. Tsirkin" <mst@...hat.com>

commit a353e0ce0fd42d8859260666d1e9b10f2abd4698 upstream.

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>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 include/linux/skbuff.h | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -1633,6 +1633,22 @@ static inline void skb_orphan(struct sk_
 }
 
 /**
+ *	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);
+}
+
+/**
  *	__skb_queue_purge - empty a list
  *	@list: list to empty
  *

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